UNIVERSITY  OF  CALIFORNIA 
AT   LOS  ANGELES 


GIFT  OF 

Mrs.   Agnes   Frisius 


JOHN  TYNDALL. 


rt* 


PREFACE. 

TO 

THE    SIXTH    EDITION. 


To  AVOID  unwieldiness  of  bulk  this  edition  of  the  "Frag- 
ments "  is  published  in  one  volume,  instead,  of  as  heretofore, 
in  two. 

The  first  part  deals  almost  exclusively  with  the  laws  and 
phenomena  of  matter.  The  second  trenches  upon  questions 
in  which  the  phenomena  of  matter  interlace  more  or  less 
with  those  of  mind. 

New  Essays  have  been  added,  while  old  ones  have  been 
revised,  and  in  part  recast.  To  be  clear,  without  being 
superficial,  has  been  my  aim  throughout. 

In  neither  part  have  I  aspired  to  sit  in  the  seat  of 
the  scornful,  but  rather  to  treat  the  questions  touched 
upon  with  a  tolerance,  if  not  a  reverence,  befitting  their 
difficulty  and  weight. 

Holding,  as  I  do,  the  nebular  hypothesis,  I  am  logically 
bound  to  deduce  the  life  of  the  world  from  forces  inherent 
in  the  nebula.  With  this  view,  it  seemed  but  fair  to  asso- 
ciate the  reasons  which  cause  me  to  conclude  that  every 
attempt  made  in  our  day  to  generate  life  independently  of 
antecedent  life  has  utterly  broken  down. 


478682 


CONTENTS. 


CHAPTER  L 

PAGE. 
The  Constitution  of  Nature 1 

CHAPTER  II. 
Radiation v  '. 20 

CHAPTER  III. 

On  Radiant  Heat  in  Relation  to  the  Color  and  Chemical  Constitu- 
tion of  Bodies 54 

CHAPTER  IV. 
New  Chemical  Reactions  Produced  by  Light 71 

CHAPTER  V. 
The  Sky 98 

CHAPTER  VI. 
Voyage  to  Algeria  to  Observe  the  Eclipse 107 

CHAPTER  VII. 
Niagara 132 

CHAPTER  VIII. 
The  Parallel  Roads  of  Glen  Roy 155 

CHAPTER  IX. 
Alpine  Sculpture 175 

CHAPTER  X. 
Recent  Experiments  on  Fog-Signals 193 

CHAPTER  XL 
On  the  Study  of  Physics 215 


vi  CONTENTS. 

CHAPTER  XII. 

PAGE. 

On  Crystalline  and  Slaty  Cleavage 232 

CHAPTER  XIII. 
On  Paramagnetic  and  Diamagnetic  Forces..-. 244 

CHAPTER  XIV. 
Physical  Basis  of  Solar  Chemistry 250 

CHAPTER  XV. 
Elementary  Magnetism 261 

CHAPTER  XVI. 
On  Force 281 

CHAPTER  XVII. 
Contributions  to  Molecular  Physics 294 

CHAPTER  XVIII. 
Life  and  Letters  of  Faraday 303 

CHAPTER  XIX. 

The  Copley  Medalist  of  1870 320 

CHAPTER  XX. 
The  Copley  Medalist  of  1871 325 

CHAPTER  XXI. 
Death  by  Lightning , ,  332 

CHAPTER  XXII. 
Science  and  the  Spirits 336 

CHAPTER  XXIII. 
Reflections  on  Prayer  and  Natural  Law 342 

CHAPTER  XXIV. 
Miracles  and  Special  Providences 348 

CHAPTER  XXV. 
On  Prayer  as  a  Form  of  Physical  Energy 371 

CHAPTER  XXVI. 
Vitality., ..  376 


CONTENTS.  vii 

CHAPTER  XXVII. 

PAGE. 

Matter  and  Force  381 

CHAPTER  XXVIII. 
Scientific  Materialism 398 

CHAPTER  XXIX. 
An  Address  to  Students 410 

CHAPTER  XXX. 
Scientific  Use  of  the  Imagination 417 

CHAPTER  XXXI. 
The  Belfast  Address 443 

CHAPTER  XXXII. 
Apology  for  the  Belfast  Address 494 

CHAPTER  XXXIII. 
The  Rev.  James  Martineau  and  the  Belfast  Address 511 

CHAPTER  XXXIV. 
Fermentation,  and  Its  Bearings  on  Surgery  and  Medicine 532 

CHAPTER  XXXV. 
Spontaneous  Generation 562 

CHAPTER  XXXVI. 
Science  and  Man 596 

CHAPTER  XXXVII. 
Professor  Virchow  and  Evolution \ 625 

CHAPTER  XXXVIII. 
The  Electric  Light 660 


FRAGMENTS  OF  SCIENCE. 


CHAPTER  I. 

THE   CONSTITUTION    OF   NATURE.* 

WE  CANNOT  think  of  space  as  finite,  for  wherever 
in  imagination  we  erect  a  boundary,  we  are  compelled 
to  think  of  space  as  existing  beyond  it.  Thus  by 
the  incessant  dissolution  of  limits  we  arrive  at  a  more 
or  less  adequate  idea  of  the  infinity  of  space.  But  though 
compelled  to  think  of  space  as  unbounded,  there  is  no 
mental  necessity  compelling  ns  to  think  of  it  either  as  filled 
or  empty;  whether  it  is  so  or  not  must  be  decided  by  ex- 
periment and  observatiorf.  That  it  is  not  entirely  void 
the  starry  heavens  declare;  but  the  question  still  remains, 
are  the  stars  themselves  hung  in  vacuo?  Are  the  vast 
regions  which  surround  them,  and  across  which  their  light 
is  propagated,  absolutely  empty?  A  century  ago  the 
answer  to  this  question,  founded  on  the  Newtonian  theory, 
would  have  been,  "  No,  for  particles  of  light  are  inces- 
santly shot  through  space."  The  reply  of  modern  science 
is  also  negative,  but  on  different  grounds.  It  has  the  best 
possible  reasons  for  rejecting  the  idea  of  luminiferous 
particles;  but  in  support  of  the  conclusion  that  the  celes- 
tial .spaces  are  occupied  by  matter,  it  is  able  to  offer  proofs 
almost  as  cogent  as  those  which  can  be  adduced  of  the 
existence  of  an  atmosphere  round  the  earth.  Men's 
minds,  indeed,  rose  to  a  conception  of  the  celestial  and  uni- 
versal atmosphere  through  the  study  of  the  terrestrial 
and  local  one.  From  the  phenomena  of  sound,  as  dis- 
played in  the  air,  they  ascended  to  the  phenomena  of 
light,  as  displayed  in  the  ether;  which  is  the  name  given  to 
the  interstellar  medium. 

The  notion  of  this  medium  must  not  be  considered  as  a 

*  "  Fortnightly  Review,"  1865,  vol.  iii.  p.  129. 


2  FRAGMENTS  OF  SCIENCE. 

vague  or  fanciful  conception  on  the  part  of  scientific  men. 
Of  its  reality  most  of  them  are  as  convinced  as  they  are  of 
the  existence  of  the  sun  and  moon.  The  luminiferous 
ether  has  definite  mechanical  properties.  It  is  almost 
infinitely  more  attenuated  than  any  known  gas,  but  its 
properties  are  those  of  a  solid  rather  than  of  a  gas.  It 
resembles  jelly  rather  than  air.  This  was  not  the  first 
conception  of  the  ether,  but  it  is  that  forced  upon  us  by  a 
more  complete  knowledge  of  its  phenomena.  A  body  thus 
constituted  may  have  its  boundaries;  but  although  the  ether 
may  not  be  co-extensive  with  space,  it  must  at  all  events 
extend  as  far  as  the  most  distant  visible  stars.  In_fact  it 
is  the  vehicle  of  their  light,  and  without  it  they  could  not 
be  seen.  This  all-prevading  substance  takes  up  their  mo- 
lecular tremors,  and  conveys  them  with  inconceivable 
rapidity  to  our  organs  of  vision.  It  is  the  transported 
shiver  of  bodies  countless  millions  of  miles  distant,  which 
translates  itself  in  human  consciousness  into  the  splendor 
of  the  firmament  at  night. 

If  the  ether  have  a  boundary,  masses  of  ponderable 
matter  might  be  conceived  to  *exist  beyond  it,  but  they 
could  emit  no  light.  Beyond  the  ether  dark  suns  might 
burn;  there,  under  proper  conditions,  combustion  might 
be  carried  on;  fuel  might  consume  unseen,  and  metals  be 
fused  in  invisible  fires.  A  body,  moreover,  once  heated 
there,  would  continue  forever  heated;  a  sun  or  planet  once 
molten,  would  continue  forever  molten.  For,  the  loss  of 
heat  being  simply  the  abstraction  of  molecular  motion  bv 
the  ether,  where  this  medium  is  absent  no  cooling  could 
occur.  A  sentient  being,  on  approaching  a  heated  body 
in  this  region,  would  be  conscious  of  no  augmentation  of 
temperature.  The  gradations  of  warmth  dependent  on 
the  laws  of  radiation  would  not  exist,  and  actual  contact 
would  first  reveal  the  heat  of  an  extra  ethereal  sun. 

Imagine  a  paddle-wheel  placed  in  water  and  caused  to 
rotate.  From  it,  as  a  center,  waves  would  issue  in  all 
directions,  and  a  wader  as  he  approached  the  place  of  dis- 
turbance would  be  met  by  stronger  and  stronger  waves. 
This  gradual  augmentation  of  the  impression  made  upon 
the  wader  is  exactly  analogous  to  the  augmentation  of 
light  when  we  approach  a  luminous  source.  In  the  one 
case,  however,  the  coarse  common  nerves  of  the  body 
suffice;  for  the  other  we  must  have  the  finer  optic  nerve. 


THE  CONSTITUTION  0 F  NA TUBE.  3 

But  suppose  the  water  withdrawn;  the  action  at  a  dis- 
tance would  then  cease,  and,  as  far  as  the  sense  of  touch  is 
concerned,  the  wader  would  be  first  rendered  conscious  of 
the  motion  of  the  wheel  by  the  blow  of  the  paddles.  The 
transference  of  motion  from  the  paddles  to  the  water  is 
mechanically  similar  to  the  transference  of  molecular 
motion  from  the  heated  body  to  the  ether;  and  the  prop- 
agation of  waves  through  the  liquid  is  mechanically 
similar  to  the  propagation  of  light  and  radiant  heat. 

As  far  as  our  knowledge  of  space  extends,  we  are  to  con- 
ceive it  as  the  holder  of  the  luminiferous  ether,  through 
which  are  interspersed,  at  enormous  distances  apart,  the 
ponderous  nuclei  of  the  stars.  Associated  with  the  star 
that  most  concerns  us  we  have  a  group  of  dark  planetary 
masses  revolving  at  various  distances  round  it,  each  again 
rotating  on  its  own  axis;  and,  finally,  associated  with 
some  of  these  planets  we  have  dark  bodies  of  minor  note — 
the  moons.  Whether  the  other  fixed  stars  have  similar 
planetary  companions  or  not  is  to  us  a  matter  of  pure  con- 
jecture, which  may  or  may  not  enter  into  our  conception 
of  the  universe.  But  probably  every  thoughtful  person  be- 
lieves, with  regard  to  those  distant  suns,  that  there  is, 
in  space,  something  besides  our  system  on  which  they 
shine. 

From  this  general  view  of  the  present  condition  of  space, 
and  of  the  bodies  contained  in  it,  we  pass  to  the  inquiry 
whether  things  were  so  created  at  the  beginning.  Was 
space  furnished  at  once,  by  the  fiat  of  Omnipotence,  with 
these  burning  orbs?  In  presence  of  the  revelations  of 
science  this  view  is  fading  more  and  more.  Behind  the 
orbs  we  now  discern  the  nebulee  from  which  they  have 
been  condensed.  And  without  going  so  far  back  as  the 
nebulae,  the  man  of  science  can  prove  that  out  of  common 
non-luminous  matter  this  whole  pomp  of  stars  might  have 
been  evolved. 

The  law  of  gravitation  enunciated  by  Newton  is,  that 
every  particle  of  matter  in  the  universe  attracts  every 
other  particle  with  a  force  which  diminishes  as  the  square 
of  the  distance  increases.  Thus  the  sun  and  the  earth 
mutually  pull  each  other;  thus  the  earth  and  the  moon 
are  kept  in  company;  the  force  which  holds  every  respec- 
tive pair  of  masses  together  being  the  integrated  force  of 
their  component  parts,  Under  the  operation  of  this  force 


4  FRA  GMENTS  OF  SCIENCE. 

a  stone  falls  to  the  ground  and  is  warmed  by  the 
shock;  under  its  operation  meteors  plunge  into  our  atmos- 
phere and  rise  to  incandescence.  Showers  of  such  meteors 
doubtless  fall  incessantly  upon  the  sun.  Acted  on  by  this 
force,  the  earth,  were  it  stopped  in  its  orbit  to-morrow, 
would  rush  toward,  and  finally  combine  with  the  sun. 
Heat  would  also  be  developed  by  this  collision.  Mayer 
first,  and  Helmholtz  and  Thomson  afterward,  have  calcu- 
lated its  amount.  It  would  equal  that  produced  by  the  com- 
bustion of  more  than  5,000  worlds  of  solid  coal,  all  this 
heat  being  generated  at  the  instant  of  collision.  In  the 
attraction  of  gravity,  therefore,  acting  upon  non-luminous 
matter,  we  have  a  source  of  heat  more  powerful  than 
could  be  derived  from  any  terrestial  combustion.  And 
were  the  matter  of  the  universe  thrown  in  cold  detached 
fragments  into  space,  and  there  abandoned  to  the  mutual 
gravitation  of  its  own  parts,  the  collision  of  the  fragments 
would  in  the  end  produce  the  fires  of  the  stars. 

The  action  of  gravity  upon  matter  originally  cold  may, 
in  fact,  be  the  origin  of  all  light  and  heat,  and  also  the 
proximate  source  of  such  other  powers  as  are  generated  by 
light  and  heat.  But  we  have  now  to  inquire  what  is  the 
light  and  what  is  the  heat  thus  produced?  This  question 
has  already  been  answered  in  a  general  way.  Both  light 
and  heat  are  modes  of  motion.  Two  planets  clash  and 
come  to  rest;  their  motion,  considered  as  that  of  masses, 
is  destroyed,  but  it  is  in  great  part  continued  as  a  motion 
of  their  ultimate  particles.  It  is  this  latter  motion, 
taken  up  by  the  ether,  and  propagated  through  it  with  a 
velocity  of  186,000  miles  a  second,  that  comes  to  us  as  the 
light  and  heat  of  suns  and  stars.  The  atoms  of  a  hot 
body  swing  with  inconceivable  rapidity — billions  of  times 
in  a  second — but  this  power  of  vibration  necessarily  implies 
the  operation  of  forces  between  the  atoms  themselves.  It 
reveals  to  us  that  while  they  are  held  together  by  one 
force,  they  are  kept  asunder  by  another,  their  position  at 
any  moment  depending  on  the  equilibrium  of  attraction 
and  repulsion.  The  atoms  behave  as  if  connected  by 
elastic  springs,  which  oppose  at  the  same  time  their  ap- 
proach and  their  retreat,  but  which  tolerate  the  vibration 
called  heat.  The  molecular  vibration  once  set  up  is  in- 
stantly shared  with  the  ether,  and  diffused  bv  it  through- 
out space. 


T11K  CONSTITUTION  OF  NA  TURK.  5 

We  on  the  earth's  surface  live  night  and  day  in  the 
midst  of  ethereal  commotion.  The  medium  is  never  still. 
The  cloud  canopy  above  us  may  be  thick  enough  to  shut 
out  the  light  of  the  stars;  but  this  canopy  is  itself  a  warm 
body,  which  radiates  its  thermal  motion  through  the  ether. 
The  earth  also  is  warm,  and  sends  its  heat-pulses  inces- 
santly forth.  It  is  the  waste  of  its  molecular  motion  in 
space  that  chills  the  earth  upon  a  clear  night;  it  is  the  re- 
turn of  thermal  motion  from  the  clouds  which  prevents  the 
earth's  temperature,  on  a  cloudy  night,  from  falling  so  low. 
To  the  conception  of  space  being  filled,  we  must  therefore 
add  the  conception  of  its  being  in  a  state  of  incessant 
tremor. 

The  sources  of  this  vibration  are  the  ponderable  masses 
of  the  universe.  Let  us  take  a  sample  of  these  and  ex- 
amine it  in  detail.  When  we  look  to  our  planet,  we  find 
it  to  be  an  aggregate  of  solids,  liquids,  and  gases.  Sub- 
jected to  a  sufficiently  low  temperature,  the  two  last  would 
also  assume  the  solid  form.  When  we  look  at  any  one  of 
these,  we  generally  find  it  composed  of  still  more  elemen- 
tary parts.  We  learn,  for  example,  that  the  water  of  our 
rivers  is  formed  by  the  union,  in  definite  proportions,  of 
two  gases,  oxygen  and  hydrogen.  We  know  how  to  bring 
these  constituents  together,  so  as  to  form  water:  we  also 
know  how  to  analyze  the  water,  and  recover  from  it  its 
two  constituents.  So,  likewise,  as  regards  the  solid  por- 
tions of  the  earth.  Our  chalk  hills,  for  example,  are 
formed  by  a  combination  of  carbon,  oxygen,  and  calcium. 
These  are  the  so  called  elements  the  union  of  which,  in  def- 
inite proportions,  has  resulted  in  the  formation  of  chalk. 
The  flints  within  the  chalk  we  know  to.  be  a  compound  of 
oxygen  and  silicium,  called  silica;  and  our  ordinary  clay  is, 
for  the  most  part,  formed  by  the  union  of  silicium,  oxygen, 
and  the  well-known  light  metal,  aluminium.  By  far  the 
greater  portion  of  the  earth's  crust  is  compounded 
of  the  elementary  substances  mentioned  in  these  few 
lines. 

The  principle  of  gravitation  has  been  already  described  j  J*/<? 
as  an  attraction  which  every  particle  of  matter,  however  I 
small,  exerts  on  every  other  particle.     With  gravity  there  /     G** 
is  no  selection;  no  particular  atoms  choose,  by  preference,  \ 
other  particular  atoms  as  objects  of  attraction;  the  attrac-    \    ^ 
tiou  of  gravitation  is  proportional  simply  to  the  quantity  J 


6  FRAGMENTS  OF  SCIENCE. 

of  the  attracting  matter,  regardless  of  its  quality.  But  in 
the  molecular  world  which  we  have  now  entered  matters 
<J  f  are  otherwise  arranged.  Here  we  have  atoms  between 
which  a  strong  attraction  is  exercised,  and  also  atoms  be- 
tween which  a  weak  attraction  is  exercised.  One  atom 
can  jostle  another  out  of  its  place,  in  virtue  of  a  superior 
But,  though  the  amount  of  force  ex- 
erted  varies  thus  from  atom  to  atom,  it  is  still  an  attraction 
of  the  same  mechanical  quality,  if  I  may  use  the  term,  as 
that  of  gravity  itself.  Its  intensity  might  be  measured  in 
the  same  way,  namely  by  the  amount  of  motion  which  it 
can  generate  in  a  certain  time.  Thus  the  attraction  of 
gravity  at  the  earth's  surface  is  expressed  by  the  number 
32;  because,  when  acting  freely  on  a  body  for  a  second 
of  time,  gravity  imparts  to  the  body  a  velocity  of  thirty- 
two  feet  a  second.  In  like  manner  the  mutual  attraction 
of  oxygen  and  hydrogen  might  be  measured  by  the  velocity 
imparted  to  the  atoms  in  their  rushing  together.  Of 
course  such  a  unit  of  time  as  a  second  is  not  here  to  be 
thought  of,  the  whole  interval  required  by  the  atoms  to 
cross  the  minute  spaces  which  separate  them  amount- 
ing only  to  an  inconceivably  small  fraction  of  a 
second. 

It  has  been  stated  that  when  a  body  falls  to  the  earth  it 
is  warmed  by  the  shock.  Here,  to  use  the  terminology  of 
Mayer,  we  have  a  mechanical  combination  of  the  earth  and 
the  body.  Let  us  suffer  the  falling  body  and  the  earth  to 
dwindle  in  imagination  to  the  size  of  atoms,  and  for  the 
attraction  of  gravity  let  us  substitute  that  of  chemical 
affinity;  we  have  then  what  is  called  a  chemical  combina- 
tion. The  effect  of  the  union  in  this  case  also  is  the  de- 
velopment of  heat,  and  from  the  amount  of  heat  generated 
we  can  infer  the  intensity  of  the  atomic  pull.  Measured 
by  ordinary  mechanical  standards,  this  is  enormous.  Mix 
eight  pounds  of  oxygen  with  one  of  hydrogen,  and  pass  a 
spark  through  the  mixture;  the  gases  instantly  combine, 
their  atoms  rushing  over  the  little  distances  which  sepa- 
rate them.  Take  a  weight  of  47,000  pounds  to  an  eleva- 
tion of  1,000  feet  above  the  earth's  surface,  and  let  it  fall; 
the  energy  with  which  it  will  strike  the  earth  will  not 
exceed  that  of  the  eight  pounds  of  oxygen  atoms,  as 
they  dash  against  one  pound  of  hydrogen* atoms  to  form 
water. 


THti  CONSTITUTION  OF  NA  TURE.  7 

It  is  sometimes  stated  that  gravity  is  distinguished 
from  all  other  forces  by  the  fact  of  its  resisting  conver- 
sion into  other  forms  of  force.  Chemical  affinity,  it  is 
said,  can  be  converted  into  heat  and  light,  and  these  again 
into  magnetism  and  electricity:  but  gravity  refuses  to  be  so 
converted;  being  a  force  maintaining  itself  under  all  cir- 
cumstances, and  not  capable  of  disappearing  to  give  place 
to  another.  The  statement  arises  from  vagueness  of 
thought.  If  by  it  be  meant  that  a  particle  of  matter  can 
never  be  deprived  of  its  weight,  the  assertion  is  correct; 
but  the  law  which  affirms  the  convertibility  of  natural 
forces  was  never  intended,  in  the  minds  o£  those  who  un- 
derstood it,  to  affirm  that  such  a  conversion  as  that  here 
implied  occurs  in  any  case  whatever.  As  regards  convert- 
ibility into  heat,  gravity  and  chemical  affinity  stand  on 
precisely  the  same  footing.  The  attraction  in  the  one  case 
is  as  indestructible  as  in  the  other.  Nobody  affirms  that 
when  a  stone  rests  upon  the  surface  of  the  earth,  the 
mutual  attraction  of  the  earth  and  stone  is  abolished; 
nobody  means  to  affirm  that  the  mutual  attraction  of 
oxygen  for  hydrogen  ceases,  after  the  atoms  have  com- 
bined to  form  water.  What  is  meant,  in  the  case  of 
chemical  affinity,  is,  that  the  pull  of  that  affinity,  acting 
through  a  certain  space,  imparts  a  motion  of  translation  of 
the  one  atom  toward  the  other.  This  motion  is  not  heat, 
nor  is  the  force  that  produces  it  heat.  But  when  the 
atoms  strike  and  recoil,  the  motion  of  translation  is  con- 
verted into  a  motion  of  vibration,  which  is  heat.  The 
vibration,  however,  so  fur  from  causing  the  extinction  of 
the  original,  attraction,  is  in  part  carried  on  by  that  at- 
traction. The  atoms  recoil,  in  virtue  of  the  elastic  force 
which  opposes  actual  contact,  and  in  the  recoil  they  are 
driven  too  far  back.  The  original  attraction  then 
triumphs  over  the  force  of  recoil,  and  urges  the  atoms  once 
more  together.  Thus,  like  a  pendulum,  they  oscillate, 
until  their  motion  is  imparted  to  the  surrounding  ether; 
or,  in  other  words,  until  their  heat  becomes  radiant 
heat. 

In  this  sense,  and  in  this  sense  only,  is  chemical  affinity 
converted  into  heat.  There  is,  first  of  all,  the  attraction 
between  the  atoms;  there  is,  secondly,  space  between  them. 
Across  this  space  the  attraction  urges  them.  They  collide, 
they  recoil,  they  oscillate.  There  is  here  a  change  in  the 


g  PR  A  GMENTS  OF  SCIENCE. 

form  of  the  motion,  but  there  is  no  real  loss.  It  is  so 
with  the  attraction  of  gravity.  To  produce  motion  by 
gravity  space  must  also  intervene  between  the  attracting 
bodies.  When  they  strike  together  motion  is  apparently 
destroyed,  but  in  reality  there  is  no  destruction.  Their 
atoms'are  suddenly  urged  together  by  the  shock;  by  their 
own  perfect  elasticity  these  atoms  recoil;  and  thus  is  set 
up  the  molecular  oscillation  which,  when  communicated 
to  the  proper  nerves,  announces  itself  as  heat. 

It  was  formerly  universally  supposed  that  by  the  colli- 
sion of  unelastic  bodies  force  was  destroyed.  Men  saw, 
for  example,  that  when  two  spheres  of  clay,  painter's 
putty,  or  lead,  for  example,  were  urged  together,  the 
motion  possessed  by  the  masses,  prior  to  impact,  was  more 
or  less  annihilated.  They  believed  in  an  absolute  de- 
struction of  the  force  of  impact.  Until  recent  times, 
indeed,  no  difficulty  was  experienced  in  believing  this, 
whereas,  at  present,  the  ideas  of  force  and  its  destruc- 
tion refuse  to  be  united  in  most  philosophic  minds.  In 
the  collision  of  elastic  bodies,  on  the  contrary,  it  was  ob- 
served that  the  motion  with  which  they  clashed  together 
was  in  great  part  restored  by  the  resiliency  of  the  masses, 
the  more  perfect  the  elasticity  the  more  complete  being 
the  restitution.  This  led  to  the  idea  of  perfectly  elastic 
bodies — bodies  competent  to  restore  by  their  recoil  the 
whole  ot  the  motion  which  they  possessed  before  impact — 
and  this  again  to  the  idea  of  the  conservation  of  force,  as 
opposed  to  that  destruction  of  force  which  was  supposed 
to  occur  when  unelastic  bodies  met  in  collision. 

We  now  know  that  the  principle  of  conservation  holds 
equally  good  with  elastic  and  unelastic  bodies.  Perfectly 
elastic  bodies  would  develop  no  heat  on  collision.  They 
would  retain  their  motion  afterward,  though  its  direction 
might  be  changed;  and  it  is  only  when  sensible  motion  is 
wholly  or  partly  destroyed,  that  heat  is  generated.  This 
always  occurs  in  unelastic  collision,  the  heat  developed 
being  the  exact  equivalent  of  the  sensible  motion  extin- 
guished. This  heat  virtually  declares  that  the  property  of 
elasticity,  dejaied  to  the  masses,  exists  among  their  atoms; 
by  the  recoifand  oscillation  of  which  the  principle  of  con- 
servation is  vindicated. 

But  ambiguity  in  the  use  of  the  term  "  force  "  makes 
itself  more  and  more  felt  as  we  proceed.  "We  have  called 


THE  CONSTITUTION  OF  NA  TURti.  9 

the  attraction  of  gravity  a  force,  without  any  reference  to 
motion.  A  body  resting  on  a  shelf  is  as  much  pulled  by 
gravity  as  when,  after  having  been  pushed  off  the  shelf,  it 
falls  toward  the  earth.  We  applied  the  term  force  also  to 
that  molecular  attraction  which  we  called  chemical  affinity. 
AVhen,  however,  we  spoke  of  the  conservation  of  force,  iu 
the  case  of  elastic  collision,  we  meant  neither  a  pull  nor  a 
push,  which,  as  just  indicated,  might  be  exerted  upon 
inert  matter,  but  we  meant  force  invested  in  motion — the 
vis  viva,  as  it  is  called,  of  the  colliding  masses. 

Force  in  this  form  has  a  definite  mechanical  measure,  in 
the  amount  of  work  that  it  can  perform.  The  simplest 
form  of  work  is  the  raising  of  a  weight.  A  man  walking 
uphill,  or  upstairs,  with  a  pound  weight  in  his  hand,  to 
an  elevation  say  of  sixteen  feet,  performs  a  certain 
amount  of  work,  over  and  above  the  lifting  of  his  own 
body.  If  he  carries  the  pound  to  a  height  of  thirty-two 
feet,  he  does  twice  the  work;  if  to  a  height  of  forty-eight 
feet,  he  does  three  times  the  work;  if  to  sixty-four  feet, 
he  does  four  times  the  work,  and  so  on.  If,  moreover,  he 
carries  up  two  pounds  instead  of  one,  other  things  being 
equal,  he  does  twice  the  work;  if  three,  four,  or  five 
pounds,  he  does  three,  four,  or  five  times  the  work.  In 
fact,  it  is  plain  that  the  work  performed  depends  on  two 
factors,  the  weight  raised  and  the  height  to  which  it  is 
raised.  It  is  expressed  by  the  product  of  these  two 
factors. 

But  a  body  may  be  caused  to  reach  a  certain  eleva- 
tion in  opposition  to  the  force  of  gravity,  without  being 
actually  carried  up.  If  a  hodman,  for  example,  wished  to 
land  a  brick  at  an  elevation  of  sixteen  feet  above  the 
place  where  he  stood,  he  would  probably  pitch  it  up  to 
the  bricklayer.  He  would  thus  impart,  by  a  sudden 
effort,  a  velocity  to  the  brick  sufficient  to  raise  it  to  the 
required  height;  the  work  accomplished  by  that  effort 
being  precisely  the  same  as  if  he  had  slowly  carried  up  the 
brick.  The  initial  velocity  to  be  imparted,  in  this  case,  is 
well  known.  %  To  reach  a  height  of  sixteen  feet,  the 
brick  must  quit  the  man's  hand  with  a  velocity  of  thirty- 
two  feet  a  second.  It  is  needless  to  say,  that  a  body  start- 
ing with  any  velocity,  would,  if  wholly  unopposed  or 
unaided,  continue  to  move  forever  with  the  same  velocity. 
But  when,  as  in  the  case  before  us,  the  body  is  thrown 


10  FR A  OMENTS  OF  SCIENCE. 

upward,  it  moves  in  opposition  to  gravity,  which  inces- 
santly retards  its  motion,  and  finally  brings  it  to  rest  at  an 
elevation  of  sixteen  feet.  If  not  here  caught  by  the  brick- 
layer, it  would  return  to  the  hodman  with  an  accelerated 
motion,  and  reach  his  hand  with  the  precise  velocity  it 
possessed  on  quitting  it. 

An  important  relation  between  velocity  and  work  is  here 
to  be  pointed  out.  Supposing  the  hodman  competent  to 
impart  to  the  brick,  at  starting,  a  velocity  of  sixty-four 
feet  a  second,  or  twice  its  former  velocity,  would  the 
amount  of  work  performed  be  twice  what  it  was  in  the 
first  instance?  No;  it  would  be  four  times  that  quantity; 
for  a  body  starting  with  twice  the  velocity  of  another,  will 
rise  to  four  times  the  height.  In  like  manner,  a  three- 
fold velocity  will  give  a  ninefold  elevation,  a  fourfold 
velocity  will  give  a  sixteenfold  elevation,  and  so  on.  The 
height  attained,  then,  is  not  proportional  to  the  initial 
velocity,  but  to  the  square  of  the  velocity.  As  before, 
the  work  is  also  proportional  to  the  weight  elevated. 
Hence  the  work  which  any  moving  mass  whatever  is  com- 
petent to  perform,  in  virtue  of  the  motion  which  it  at  any 
moment  possesses,  is  jointly  proportional  to  its  weight  and 
the  square  of  its  velocity.  Here,  then,  we  have  a  second 
measure  of  work,  in  which  we  simply  translate  the  idea  of 
height  into  its  equivalent  idea  of  motion. 

In  mechanics,  the  product  of  the  mass  of  a  moving  body 
into  the  square  of  its  velocity,  expresses  what  is  called 
the  vis  viva,  or  living  force.  It  is  also  sometimes  called 
the  "mechanical  effect."  If,  for  example,  a  cannon 
pointed  to  the  zenith  urge  a  ball  upward  with  twice  the 
velocity  imparted  to  a  second  ball,  the  former  will  rise  to 
four  times  the  height  attained  by  the  latter.  If  directed 
against  a  target,  it  will  also  do  four  times  the  execution. 
Hence  the  importance  of  imparting  a  high  velocity  to 
projectiles  in  war.  Having  thus  cleared  our  way  to  a  per- 
fectly definite  conception  of  the  vis  viva  of  moving  masses, 
we  are  prepared  for  the  announcement  that  the  heat 
generated  by  the  shock  of  a  falling. body  against  the 
earth  is  proportional  to  the  vis  viva  annihilated.  The 
heat  is  proportional  to  the  square  of  the  velocity.  In  the 
case,  therefore,  of  two  cannon-balls  of  equal  weight,  if 
one  strike  a  target  with  twice  the  velocity  of  the  other, 
it  will  generate  four  times  the  heat,  if  with  three  times 


THE  CONSTITUTION  OF  NA TURE.  1 1 

the  velocity,  it  will  generate  nine  times  the  heat,  and  so 
on. 

Mr.  Joule  has  shown  that  a  pound  weight  falling  from 
a  height  of  772  feet,  or  772  pounds  falling  through  one 
foot,  will  generate  by  its  collision  with  the  earth  an 
amount  of  heat  sufficient  to  raise  a  pound  of  water  one  de- 
gree Fahrenheit  in  temperature.  772  "  foot-pounds" 
constitute  the  mechanical  equivalent  of  heat.  Now,  a 
body  falling  from  a  height  of  772  feet,  has,  npon  striking 
the  earth,  a  velocity  of  223  feet  a  second;  and  if  this 
velocity  were  imparted  to  the  body,  by  any  other  means, 
the  quantity  of  heat  generated  by  the  stoppage  of  its 
motion  would  be  that  stated  above.  Six  times  that 
velocity,  or  1,388  feet,  would  not  be  an  inordinate  one  for  a 
cannon-ball  as  it  quits  the  gun.  Hence,  a  cannon-ball 
moving  with  a  verocity  of  1,338  feet  a  second,  would,  by 
collision,  generate  an  amount  of  heat  competent  to  raise 
its  own  weight  of  water  36  degrees  Fahrenheit  in 
temperature.  If  composed  of  iron,  and  if  all  the  heat 
generated  were  concentrated  in  the  ball  itself,  its  tempera- 
ture would  be  raised  about  360  degrees  Fahrenheit; 
because  one  degree  in  the  case  of  water  is  equivalent  to 
about  ten  degrees  in  the  case  of  iron.  In  artillery  prac- 
tice, the  heat  generated  is  usually  concentrated  upon  the 
front  of  the  bolt,  and  on  the  portion  of  the  target  first 
struck.  By  this  concentration  the  heat  developed  be- 
comes sufficiently  intense  to  raise  the  dust  of  the  metal  to 
incandescence,  a  flash  of  light  often  accompanying  colli- 
sion with  the  target. 

Let  us  now  fix  our  attention  for  a  moment  on  the  gun- 
powder which  urges  the  cannon-ball.  This  is  composed 
of  combustible  matter,  which  if  burned  in  the  open  air 
would  yield  a  certain  amount  of  heat.  It  will  not  yield 
this  amount  if  it  perform  the  work  of  urging  a  ball.  The 
heat  then  generated  by  the  gunpowder  will  fall  short 
of  that  produced  in  the  open  air,  by  an  amount  equiva- 
lent to  the  vis  viva  of  the  ball;  and  this  exact  amount 
is  restored  by  the  ball  on  its  collision  with  the  target. 
In  this  perfect  way  are  heat  and  mechanical  motion 
connected. 

Broadly  enunciated,  the  principle  of  the  conservation 
of  force  asserts,  that  the  quantity  of  force  in  the  universe 
is  as  unalterable  as  the  quantity  of  matter;  that  it  is  alike 


1%  FRAGMENTS 

impossible  to  create  force  and  to  annihilate  it.  But  in 
what  sense  are  we  to  understand  this  assertion?  It  would 
be  manifestly  inapplicable  to  the  force  of  gravity  as  de- 
fined by  Newton;  for  this  is  a  force  varying  inversely  as 
the  square  of  the  distance;  and  to  affirm  the  constancy  of  a 
varying  force  would  be  self-contradictory.  Yet,  when  the 
question  is  properly  understood,  gravity  forms  no  excep- 
tion to  the  law  of  conservation.  Following  the  method 
pursued  by  Helmholtz,  I  will  here  attempt  an  elementary 
exposition  of  this  law.  Though  destined  in  its  applica- 
tions to  produce  momentous  changes  in  human  thought, 
it  is  not  difficult  of  comprehension. 

For. the  sake  of  simplicity  we  will  consider  a  particle  of 
matter,  which  we  may  call  F,  to  be  perfectly  fixed,  and  a 
second  movable  particle,  D,  placed  at  a  distance  from  F. 
We  will  assume  that  these  two  particles  attract  each 
other  according  to  the  Newtonian  law.  At  a  certain  dis- 
tance, the  attraction  is  of  a  certain  definite  amount,  which 
might  be  determined  by  means  of  a  spring  balance.  At 
half  this  distance  the  attraction  would  be  augmented 
four  times;  at  a  third  of  the  distance,  nine  times;  at  one- 
fourth  of  the  distance,  sixteen  times,  and  so  on.  In 
every  case,  the  attraction  might  be  measured  by  deter- 
mining, with  the  spring  balance,  the  amount  of  tension 
just  sufficient  to  prevent  D  from  moving  toward  F.  Thus 
far  we  have  nothing  whatever  to  do  with  motion;  we  deal 
with  statics,  not  with  dynamics.  We  simply  take  into  ac- 
count the  distance  of  D  from  F,  and  the  pull  exerted  by 
gravity  at  that  distance. 

It  is  customary  in  mechanics  to  represent  the  magnitude 
of  a  force  by  a  line  of  a  certain  length,  a  force  of  double 
magnitude  being  represented  by  a  line  of  double  length, 
and  so  on.  Placing  then  the  particle  D  at  a  distance 
from  F,  we  can,  in  imagination,  draw  a  straight  line  from 
D  to  F,  and  at  D  erect  a  perpendicular  to  this  line,  which 
shall  represent  the  amount  of  the  attraction  exerted  on  D. 
If  D  be  at  a  very  great  distance  from  F,  the  attraction  will 
be  very  small,  and  the  perpendicular  consequently  very 
short.  If  the  distance  be  practically  infinite,  the  attrac- 
tion is  practically  nil.  Let  us  now  suppose  at  every  point 
in  the  line  joining  F  and  D,  a  perpendicular  to  be  erected, 
proportional  in  length  to  the  attraction  exerted  at  that 
point;  we  thus  obtain  an  infinite  number  of  perpendicu- 


THE  CONSTITUTION  OF  NA  TURE.  13 

lars,  of  gradually  increasing  length,  as  D  approaches  F. 
Uniting  the  ends  of  all  these  perpendiculars,  we  obtain  a 
curve,  and  between  this  curve  and  the  straight  line  joining 
F  and  i)  we  have  an  area  containing  all  the  perpendiculars 
placed  side  by  side.  Each  one  of  this  infinite  series  of 
perpendiculars  representing  an  attraction,  or  tension,  as  it 
is  sometimes  called,  the  area  just  referred  to  represents 
the  sum  of  the  tensions  exerted  upon  the  particle  D  dur- 
ing, its  passage  from  its  first  position  to  F. 

Up  to  the  present  point  we  have  been  dealing  with  ten- 
sions, not  with  motion.  Thug  far  vis  viva  has  been 
entirely  foreign  to  our  contemplation  of  D  and  F.  Let  us 
now  suppose  D  placed  at  a  practically  infinite  distance 
from  F;  here,  as  stated,  the  pull  of  gravity  would  be 
infinitely  small,  and  the  perpendicular  representing  it  would 
dwindle  almost  to  a  point.  In  this  position  the  sum  of 
the  tensions  capable  of  being  exerted  on  D  would  be  a 
maximum.  Let  D  now  begin  to  move  in  obedience  to  the 
infinitesimal  attraction  exerted  upon  it.  Motion  being 
once  set  up,  the  idea  of  vis  viva  arises.  In  moving  toward 
F  the  particle  D  consumes,  as  it  were,  the  tensions.  Let 
us  fix  our  attention  on  D,  at  any  point  of  the  path  over 
which  it  is  moving.  Between  that  point  and  F  there  is  a 
quantity  of  unused  tensions;  beyond  that  point  the  ten- 
sions have  been  all  consumed,  but  we  have  in  their  place 
an  equivalent  quantity  of  vis  viva.  After  D  has  passed 
any  point,  the  tension  previously  in  store  at  that  point 
disappears,  but  not  without  having  added,  during  the  in- 
finitely small  duration  of  its  action,  a  due  amount  of 
motion  to  that  previously  possessed  by  D.  The  nearer  D 
approaches  to  F,  the  smaller  is  the  sum  of  the  tensions  re- 
maining, but  the  greater  is  the  vis  viva;  the  farther  D  is 
from  F,  the  greater  is  the  sum  of  the  unconsurned  ten- 
sions, and  the  less  is  the  living  force.  Now  the  principle 
of  conservation  affirms  not  the  constancy  of  the  value  of 
the  tensions  of  gravity,  nor  yet  the  constancy  of  the  vis 
viva,  taken  separately,  but  the  absolute  constancy  of  the 
value  of  both  taken  together.  At  the  beginning  the  vis 
viva  was  zero,  and  the  tension  area  was  a  maximum;  close 
to  F  the  vis  viva  is  a  maximum,  while  the  tension  area  is 
zero.  At  every  other  point  the  work-producing  power  of 
the  particle  D  consists  in  part  of  vis  viva,  and  in  part  of 
tensions. 


14  FRA  GMENTS  OF  SCIENCE. 

If  gravity,  instead  of  being  attraction,  were  repulsion, 
then,  with  the  particles  in  contact,  the  sum  of  the  tensions 
between  D  and  F  would  be  a  maximum,  and  the  vis  viva 
zero.  If,  in  obedience  to  the  repulsion,  D  moved  away 
from  F,  vis  viva  would  be  generated;  and  the  farther  D 
retreated  from  F  the  greater  would  be  its  vis  viva,  and 
the  less  the  amount  of  tension  still  available  for  producing 
motion.  Taking  repulsion  as  well  as  attraction  into  ac- 
count, the  principle  of  the  conservation  of  force  affirms 
that  the  mechanical  value  of  the  tensions  and  vires  vivce 
of  the  material  universe,  so  far  as  we  know  it,  is  a  con- 
stant quantity.  The  universe,  in  short,  possesses  two 
kinds  of  property  which  are  mutually  convertible.  The 
diminution  of  either  carries  with  it  the  "enhancement  of 
the  other,  the  total  value  of  the  property  remaining  un- 
changed. 

The  considerations  here  applied  to  gravity  apply 
equally  to  chemical  affinity.  In  a  mixture  of  oxygen  and 
hydrogen  the  atoms  exist  apart,  but  by  the  application  of 
proper  means  they  may  be  caused  to  rush  together  across 
that  space  that  separates  them.  While  this  space  exists, 
and  as  long  as  the  atoms  have  not  begun  to  move  toward 
each  other,  we  have  tensions  and  nothing  else.  During 
their  motion  toward  each  other  the  tensions,  as  in  the  case 
of  gravity,  are  converted  into  vis  viva.  After  they  clash 
we  have  still  vis  viva,  but  in  another  form.  It  was  trans- 
lation, it  is  vibration.  It  was  molecular  transfer,  it  is 
heat. 

It  is  possible  to  reverse  these  processes,  to  unlock  the 
combined  atoms  and  replace  them  in  their  first  positions. 
But,  to  accomplish  this,  as  much  heat  would  be  required 
as  was  generated  by  their  union.  Such  reversals  occur 
daily  and  hourly  in  nature.  By  the  solar  waves,  the 
oxygen  of  water  is  divorced  from  its  hydrogen  in  the  leaves 
of  plants.  As  molecular  vis  viva  the  waves  disappear,  but 
in  so  doing  they  re-endow  the  atoms  of  oxygen  and 
hydrogen  with  tension.  The  atoms  are  thus  enabled  to 
recombine,  and  when  they  do  so  they  restore  the  precise 
amount  of  heat  consumed  in  their  separation.  The  same 
remarks  apply  to  the  compound  of  carbon  and  oxygen, 
called  carbonic  acid,  which  is  exhaled  from  our  lungs, 
produced  by  our  fires,  and  found  sparingly  diffused  every- 
where throughout  the  air.  In  the  leaves  of  plants  the  sun- 


THE  CONSTITUTION  OF  NATURE.  15 

beams  also  wrench  the  atoms  of  carbonic  acid  asunder,  and 
sacrifice  themselves  in  the  act;  but  when  the  plants  are 
burned,  the  amount  of  heat  consumed  in  their  production 
is  restored. 

This,  then,  is  the  rhythmic  play  of  Nature  as  regards 
her  forces.  Throughout  all  her  regions  she  oscillates  from 
tension  to  vis  viva,  from  vis  viva  to  tension.  We  have  the 
same  play  in  the  planetary  system.  The  earth's  orbit  is 
an  ellipse,  one  of  the  foci  of  which  is  occupied  by  the  sun. 
Imagine  the  earth  at  the  most  distant  part  of  the  orbit. 
Her  motion,  and  consequently  her  vis  viva,  is  then  a 
minimum.  The  planet  rounds  the  curve,  and  begins  its 
approach  to  the  sun.  In  front  it  has  a  store  of  tensions, 
which  are  gradually  consumed,  an  equivalent  amount  of 
vis  viva  being  generated.  When  nearest  to  the  sun  the 
motion,  and  consequently  .the  vis  viva,  reach  a  maximum. 
But  here  the  available  tensions  have  been  used  up.  The 
earth  rounds  this  portion  of  the  curve  and  retreats  from 
the  sun.  Tensions  are  now  stored  up,  but  vis  viva  is  lost, 
to  be  again  restored  at  the  expense  of  the  complementary 
force  on  the  opposite  side  of  the  curve.  Thus  beats  the 
heart  of  the  universe,  but  without  increase  or  diminution 
of  its  total  stock  of  force. 

I  have  thus  far  tried  to  steer  clear  amid  confusion,  by 
fixing  the  mind  of  the  reader  upon  things  rather  than  upon 
names.  But  good  names  are  essential;  and  here,  as  yet, 
we  are  not  provided  with  such.  We  have  had  the  force  of 
gravity  and  living  force — two  utterly  distinct  things.  We 
have  had  pulls  and  tensions;  and  we  might  have  had 
the  force  of  heat,  the  force  of  light,  the  force  of  magnet- 
ism, or  the  force  of  electricity — all  of  which  terms  have 
been  employed  more  or  less  loosely  by  writers  on  physics. 
This  confusion  is  happily  avoided  by  the  introduction  of 
the  term  "  energy,"  which  embraces  both  tension  and  vis 
viva.'  Energy  is  possessed  by  bodies  already  in  motion; 
it  is  then  actual,,  and  we  agree  to  call  it  actual  or  dynamic 
energy.  It  is  our  old  vis  viva.  On  the  other  hand, 
energy  is  possible  to  bodies  not  in  motion,  but  which,  in 
virtue  of  attraction  or  repulsion,  possess  a  power  of  motion 
which  would  realize  itself  if  all  hindrances  were  removed. 
Looking,  for  example,  at  gravity;  a  body  on  the  earth's 
surface  in  a  position  from  which  it  cannot  fall  to  a  lower 
one  possesses  no  energy.  It  has  neither  motion  nor  power 


16  FRAGMENTS  OF  SCIENCE. 

of  motion.  But  the  same  body  suspended  at  a  height 
above  the  earth  has  a  power  of  motion,  though  it  may  not 
have  exercised  it.  Energy  is  possible  to  such  a  body,  and 
we  agree  to  call  this  potential  energy.  It  consists  of  our 
old  tensions.  We,  moreover,  speak  of  the  conservation  of 
energy,  instead  of  the  conservation  of  force;  and  say  that 
the  sum  of  the  potential  and  dynamic  energies  of  the  ma- 
terial universe  is  a  constant  quantity. 

A  body  cast  upward  consumes  the  actual  energy  of  pro- 
jection, and  lays  up  potential  energy.  When  it  reaches 
its  utmost  height  all  its  actual  energy  is  consumed,  its 
potential  energy  being  then  a  maximum.  When  it  re- 
turns, there  is  a  reconversion  of  the  potential  into  the 
actual.  A  pendulum  at  the  limit  of  its  swing  possesses 
potential  energy;  at  the  lowest  point  of  its  arc  its  energy 
is  all  actual.  A  patch  of  snow  resting  on  a  mountain  slope 
has  potential  energy;  loosened,  and  shooting  down  as  an 
avalanche,  it  possesses  dynamic  energy.  The  pine-trees 
growing  on  the  Alps  have  potential  energy;  but  rushing 
down  the  Holzrinne  of  the  woodcutters  they  possess  actual 
energy.  The  same  is  true  of  the  mountains  themselves. 
As  long  as  the  rocks  which  compose  them  can  fall  to  a 
lower  level,  they  possess  potential  energy,  which  is  con- 
verted into  actual  when  the  frost  ruptures  their  cohesion 
and  hands  them  over  to  the  action  of  gravity.  The  stone 
avalanches  of  the  Matterhorn  and  Weisshorn  are  illustra- 
tions in  point.  The  hammer  of  the  great  bell  of  West- 
minster, when  raised  before  striking,  possesses  potential 
energy;  when  it  falls,  the  energy  becomes  dynamic;  and 
after  the  stroke,  we  have  the  rhythmic  play  of  potential 
and  dynamic  in  the  vibrations  of  the  bell.  The  same  holds 
good  for  the  molecular  oscillations  of  a  heated  body.  An 
atom  is  driven  against  its  neighbor,  and  recoils.  The  ulti- 
mate amplitude  of  the  recoil  being  attained,  the  motion  of 
the  atom  in  that  direction  is  checked,  and  for  an  instant 
its  energy  is  all  potential.  It  is  then  drawn  toward  its 
neighbor  with  accelerated  speed;  thus,  by  attraction,  con- 
verting its  potential  into  dynamic  energy.  Its  motion  in 
this  direction  is  also  finally  checked,  and  again,  for  an  in- 
stant, its  energy  is  all  potential.  It  once  more  retreats, 
converting,  by  repulsion,  its  potential  into  dynamic  energy, 
till  the  latter  attains  a  maximum,  after  which  it  is  again 
Changed  into  potential  energy.  Thus,  what  is  true  of  the 


THE  CONSTITUTION  OF  NATURE.  17 

earth,  as  she  swings  to  and  fro  in  her  yearly  journey  round 
the  sun,  is  also  true  of  her  minutest  atom.  We  have  wheels 
within  wheels,  and  rhythm  within  rhythm. 

When  a  body  is  heated,  a  change  of  molecular  arrange- 
ment always  occurs,  and  to  produce  this  change  heat  is 
consumed.  Hence,  a  portion  only  of  the  heat  communi- 
cated to  the  body  remains  as  dynamic  energy.  Looking 
back  on  some  of  the  statements  made  at  the  beginning  of 
this  article,  now  that  our  knowledge  is  more  extensive,  we 
see  the  necessity  of  qualifying  them.  When,  for  example, 
two  bodies  clash,  heat  is  generated;  but  the  heat,  or  molec- 
ular dynamic  energy,  developed  at  the  moment  of  colli- 
sion, is  not  the  exact  equivalent  of  the  sensible  dynamic 
energy  destroyed.  The  true  equivalent  is  this  heat,  plus 
the  potential  energy  conferred  upon  the  molecules  by  the 
placing  of  greater  distances  between  them.  This  molecular 
potential  energy  is  afterward,  on  the  cooling  of  the  body, 
converted  into  heat. 

Wherever  two  atoms  capable  of  uniting  together  by 
their  mutual  attractions  exist  separately,  they  form  a 
store  of  potential  energy.  Thus  our  woods,  forests,  and 
coal-fields  on  the  one  hand,  and  our  atmospheric  oxygen 
on  the  other,  constitute  a  vast  store  of  energy  of  this  kind 
— vast,  but  far  from  infinite.  We  have,  besides  our  coal- 
fields, metallic  bodies  more  or  less  sparsely  distributed 
through  the  earth's  crust.  These  bodies  can  be  oxydized; 
and  hence  they  are,  so  far  as  they  go,  stores  of  energy. 
But  the  attractions  of  the  great  mass  of  the  earth's  crust 
are  already  satisfied,  and  from  them  no  further  energy  can 
possibly  be  obtained.  Ages  ago  the  elementary  constitu- 
ents of  our  rocks  clashed  together  and  produced  the 
motion  of  heat,  which  was  taken  up  by  the  ether  and  car- 
ried away  through  stellar  space.  It  is  lost  forever  as  far  as 
we  are  concerned.  In  those  ages  the  hot  conflict  of  carbon, 
oxygen,  and  calcium  produced  the  chalk  and  limestone 
hills  which  are  now  cold;  and  from  this  carbon,  oxygen, 
and  calcium  no  further  energy  can  be  derived.  So  it  is 
with  almost  all  the  other  constituents  of  the  earth's  crust. 
They  took  their  present  form  in  obedience  to  molecular 
force;  they  turned  their  potential  energy  into  dynamic, 
and  yielded  it  as  radiant  heat  to  the  universe,  ages  before 
man  appeared  upon  this  planet.  For  him  a  residue  of 
potential  energy  remains,  vast,  truly,  in  relation  to  the  life 


18  FRAGMENTS  OF  SCIENCE. 

and  wants  of  an  individual,  but  exceedingly  minute  in  com- 
parison with  the  earth's  primitive  store. 

To  sum  up.  The  whole  stock  of  energy  or  working- 
power  in  the  world  consists  of  attractions,  repulsions,  and 
motions.  If  the  attractions  and  repulsions  be  so  circum- 
stanced as  to  be  able  to  produce  motion,  they  are  sources  of 
working-power,  but  not  otherwise.  As  stated  a  moment 
ago,  the  attraction  exerted  between  the  earth  and  a  body 
at  a  distance  from  the  earth's  surface,  is  a  source  of  work- 
ing-power; because  the  body  can  be  moved  by  the  attrac- 
tion, and  in  falling  can  perform  work.  When  it  rests  at  its 
lowest  level  it  is  not  a  source  of  power  or  energy,  because 
it  can  fall  no  farther.  But  though  it  has  ceased  to  be  a 
source  of  enerqy,  the  attraction  of  gravity  still  acts  as  a 
force,  which  holds  the  earth  and  weight  together. 

The  same  remarks  apply  to  attracting  atoms  and  mole- 
cules. As  long  as  distance  separates  them,  they  can  move 
across  it  in  obedience  to  the  attraction;  and  the  motion 
thus  produced  may,  by  proper  appliances,  be  caused  to 
perform  mechanical  work.  When,  for  example,  two  atoms 
of  hydrogen  unite  with  one  of  oxygen,  to  form  water,  the 
atoms  are  first  drawn  toward  each  other — they  move,  they 
clash,  and  then  by  virtue  of  their  resiliency,  they  recoil  and 
quiver.  To  this  quivering  motion  we  give  the  name  of 
heat.  This  atomic  vibration  is  merely  the  redistribution 
of  the  motion  produced  by  the  chemical  affinity;  and  this 
is  the  only  sense  in  which  chemical  affinity  can"  be  said  to 
be  converted  into  heat.  We  must  not  imagine  the  chem- 
ical attraction  destroyed,  or  converted  in'to  anything  else. 
For  the  atoms,  when  mutually  clasped  to  form  a  molecule 
of  water,  are  held  together  by  the  very  attraction  which 
first  drew  them  toward  each  other.  That  which  has  really 
been  expended  is  the  pull  exerted  through  the  space  by 
which  the  distance  between  the  atoms  has  been  dimin- 
ished. 

If  this  be  understood,  it  will  be  at  once  seen  that  gravity, 
as  before  insisted  on,  may,  in  this  sense,  be  said  to  be  con- 
vertible into  heat;  that  it  is  in  reality  no  more  an  outstand- 
ing and  inconvertible  agent,  as  it  is  sometimes  stated  to  be, 
than  is  chemical  affinity.  By  the  exertion  of  a  certain  pull 
through  a  certain  space,  a  body  is  caused  to  clash  with  a 
certain  definite  velocity  against  the  earth.  Heat  is  there- 
by developed,  and  this  is  the  only  sense  in  which  gravity 


THE  CONSTITUTION  OF  NATVRE.  19 

can  be  said  to  be  converted  into  heat.  In  no.  case  is  the 
force  which  produces  the  motion  annihilated  or  changed 
into  anything  else.  The  mutual  attraction  of  the  earth 
and  weight  exists  when  they  are  in  contact,  as  when  they 
were  separate;  but  the  ability  of  that  attraction  to  employ 
itself  in  the  production  of  motion  does  not  exist. 

The  transformation,  in  this  case,  is  easily  followed  by  the 
mind's  eye.  First,  the  weight  as  a  whole  is  set  in  motion 
by  the  attraction  of  gravity.  This  motion  of  the  mass  is 
arrested  by  collision  with  the  earth,  being  broken  up  into 
molecular  tremors,  to  which  we  give  the  name  of  heat. 

And  when  we  reverse  the  process,  and  employ  those 
tremors  of  heat  to  raise  a  weight — which  is  done  through 
the  intermediation  of  an  elastic  fluid  in  the  steam-engine 
— a  certain  definite  portion  of  the  molecular  motion  is 
consumed.  In  this  sense,  and  in  this  sense  only,  can  the 
heat  be  said  to  be  converted  into  gravitv  ;  or,  more  cor- 
rectly, into  potential  energy  of  gravity.  Here  the  destruc- 
tion of  the  heat  has  created  no  new  attraction  ;  but  the  old 
attraction  has  conferred  upon  it  a  power  of  exerting  a  cer- 
tain definite  pull,  between  the  starting-point  of  the  falling 
weight  and  the  earth. 

When,  therefore,  writers  on  the  conservation  of  energy 
speak  of  tensions  being  "consumed  "  and  "  generated,"  they 
do  not  mean  thereby  that  old  attractions  have  been  anni- 
hilated, and  new  ones  brought  into  existence,  but  that,  in 
the  one  case,  the  power  of  the  attraction  to  produce 
motion  has  been  diminished  by  the  shortening  of  the  dis- 
tance between  the  attracting  bodies,  while,  in  the  other 
case,  the  power  of  producing  motion  has  been  augmented 
by  the  increase  of  the  distance.  These  remarks  apply  to 
all  bodies,  whether  they  be  sensible  masses  or  molecules. 

Of  the  inner  quality  that  enables  mutter  to  attract  mat- 
ter we  know  nothing ;  and  the  law  of  conservation  makes 
no  statement  regarding  that  quality.  It  takes  the  facts  of 
attraction  as  they  stand,  and  affirms  only  the  constancy  of 
working-power.  That  power  may  exist  in  the  form  of 
MOTION  ;  or  it  may  exist  in  the  form  of  FORCE,  with  dis- 
tance to  act  through.  The  former  is  dynamic  energy,  the 
latter  is  potential  energy,  the  constancy  of  the  sum  of  both 
being  affirmed  by  the  law  of  conservation.  The  converti- 
bility of  natural  forces  consists  solely  in  transformations  of 
dynamic  into  potential,  and  of  potential  into  dynamic 


20  FRAGMENTS  OF  SCIENCE. 

energy.     In  no  other  sense  has  the   convertibility  of  force 
any  scientific  meaning. 

Grave  errors  have  been  entertained  as  to  what  is  really 
intended  to  be  conserved  by  the  doctrine  of  conservation. 
This  exposition  I  hope  will  tend  to  remove  them. 


CHAPTER  II. 

RADIATION.* 

1.      Visible  and  Invisible  Radiation. 

BETWEEN  the  mind  of  man  and  the  outer  world  are  inter- 
posed the  nerves  of  the  human  body,  which  translate,  or 
enable  the  mind  to  translate,  the  impressions  of  that  world 
into  facts  of  consciousness  and  thought. 

Different  nerves  are  suited  to  the  perception  of  different 
impressions.  We  do  not  see  with  the  ear,  nor  hear  with 
the  eye,  nor  are  we  rendered  sensible  of  sound  by  the 
nerves  of  the  tongue.  Out  of  the  general  assemblage  of 
physical  actions,  each  nerve,  or  group  of  nerves,  selects 
and '  responds  to  those  for  the  perception  of  which  it  is 
specially  organized. 

The  optic  nerve  passes  from  the  brain  to  the  back  of  the 
eyeball  and  there  spreads  out,  to  form  the  retina,  a  web  of 
nerve  filaments,  on  which  the  images  of  external  objects 
are  projected  by  the  optical  portion  of  the  eye.  This  nerve 
is  limited  to  the  apprehension  of  the  phenomena  of  radia- 
tion, and,  notwithstanding  its  marvelous  sensibility  to  cer- 
tain impressions  of  this  class,  it  is  singularly  obtuse  to 
other  impressions. 

Nor  does  the  optic  nerve  embrace  the  entire  range  even 
of  radiation.  Some  rays,  when  they  reach  it,  are  incompe- 
tent to  evoke  its  power,  while  others  never  reach  it  at  all, 
being  absorbed  by  the  humors  of  the  eye.  To  all  rays 
which,  whether  they  reach  the  retina  or  not,  fail  to  excite 
vision,  we  give  the  name  of  invisible  or  obscure  rays.  All 
non-luminous  bodies  emit  such  rays.  There  is  no  body  in 
nature  absolutely  cold,  and  every  body  not  absolutely  cold 
emits  rays  of  heat.  But  to  render  radiant  heat  fit  to  affect 

*  The  Rede  Lecture  delivered  in  the  Senate  House  before  the  Uni- 
versity of  Cambridge,  May  16,  1865. 


RADIATION.  21 

the  optic  nerve  a  certain  temperature  is  necessary.  A  cool 
poker  thrust  into  a  fire  remains  dark  for  a  time,  but  when 
its  temperature  lias  become  equal  to  that  of  the  surround- 
ing coals,  it  glows  like  them.  In  like  manner,  if  a  cur- 
rent of  electricity,  of  gradually  increasing  strength,  be  sent 
through  a  wire  of  the  refractory  metal  platinum,  the  wire 
first  becomes  sensibly  warm  to  the  touch;  for  a  time  its 
heat  augments,  still  however  remaining  obscure;  at  length 
we  can  no  longer  touch  the  metal  with  impunity;  and  at  a 
certain  definite  temperature  it  emits  a  feeble  red  light.  As 
the  current  augments  in  power  the  light  augments  in 
brilliancy,  until  finally  the  wire  appears  of  a  dazzling 
white.  The  light  which  it  now  emits  is  similar  to  that  of 
the  sun. 

By  means  of  a  prism  Sir  Isaac  Newton  unraveled  the 
texture  of  solar  light,  and  by  the  same  simple  instrument 
we  can  investigate  the  luminous  changes  of  our  platinum 
wire.  In  passing  through  the  prism  all  its  rays  (and  they 
are  infinite  in  variety)  are  bent  or  refracted  from  their 
straight  course;  and,  as  different  rays  are  differently 
refracted  by  the  prism,  we  are  by  it  enabled  to  separate 
one  class  of  rays  from  another.  By  such  prismatic  analy- 
sis Dr.  Draper  has  shown,  that  when  the  platinum  wire 
first  begins  to  glow,  the  light  emitted  is  sensibly  red.  As 
the  glow  augments  the  red  becomes  more  brilliant,  but  at 
the  same  time  orange  rays  are  added  to  the  emission.  Aug- 
menting the  temperature  still  further,  yellow  rays  appear 
beside  the  orange;  after  the  yellow,  green  rays  are  emitted; 
and  after  the  green  come,  in  succession,  blue,  indigo,  and 
violet  rays.  To  display  all  these  colors  at  the  same  time 
the  platinum  wire  must  be  wliite-liot:  the  impression  of 
whiteness  being  in  fact  produced  by  the  simultaneous 
action  of  all  these  colors  on  the  optic  nerve. 

In  the  experiment  just  described  we  began  with  a  plati- 
num wire  at  an  ordinary  temperature,  and  gradually  raised  it 
to  a  white  heat.  At  the  beginning,  and  even  before  the 
electric  current  had  acted  at  all  upon  the  wire,  it  emitted 
invisible  rays.  For  some  time  after  the  action  of  the  cur- 
rent had  commenced,  and  even  for  a  time  after  the  wire 
had  become  intolerable  to  the  touch,  its  radiation  was  still 
invisible.  The  question  now  arises,  What  becomes  of 
these  invisible  rays  when  the  visible  ones  make  their  ap- 
pearance? It  will  be  proved'  in  the  sequel  that  they  main- 


22  FRAGMENTS  OF  SCIENCE. 

tain  themselves  in  the  radiation;  that  a  ray  once  emitted 
continues  to  be  emitted  when  the  temperature  is  increased, 
and  hence  the  emission  from  our  platinum  wire,  even 
when  it  has  attained  its  maximum  brilliancy,  consists  of  a 
mixture  of  visible  and  invisible  rays.  If,  instead  of  the 
platinum  wire,  the  earth  itself  were  raised  to  incandes- 
cence, the  obscure  radiation  which  it  now  emits  would 
continue  to  be  emitted.  To  reach  incandescence  the  planet 
would  have  to  pass  through  all  the  stages  of  non-luminous 
radiation,  and  the  final  emission  would  embrace  the  rays 
of  all  these  stages.  There  can  hardly  be  a  doubt  that  from 
the  sun  itself  rays  proceed  similar  in  kind  to  those  which 
the  dark  earth  pours  nightly  into  space.  In  fact,  the 
various  kind  of  obscure  rays  emitted  by  all  the  planets  of 
our  system  are  included  in  the  present  radiation  of  the  sun. 

The  great  pioneer  in  this  domain  of  science  was  Sir  Will- 
iam Herschel.  Causing  a  beam  of  solar  light  to  pass 
through  a  prism,  he  resolved  it  into  its  colored  constitu- 
ents; he  formed  what  is  technically  called  the  solar  spec- 
trum. Exposing  thermometers  to  the  successive  colors 
he  determined  their  heating  power,  and  found  it  to  aug- 
ment from  the  violet  or  most  refracted  end,  to  the  red  or 
least  refracted  end  of  the  spectrum.  But  he  did  not  stop 
here.  Pushing  his  thermometers  into  the  dark  space  be- 
yond the  red  he  found  that,  though  the  light  had  disap- 
peared, the  radiant  heat  falling  on  the  instruments  was 
more  intense  than  that  at  any  visible  part  of  the  spectrum. 
In  fact,  Sir  William  Herschel  showed,  and  his  results  have 
been  verified  by  various  philosophers  since  his  time,  that, 
besides  its  luminous  rays,  the  sun  pours  forth  a  multitude 
of  other  rays,  more  powerfully  calorific  than  the  luminous 
ones,  but  entirely  unsuited  to  the  purposes  of  vision. 

At  the  less  refrangible  end  of  the.  solar  spectrum,  then, 
the  range  of  the  sun's  radiation  is  not  limited  by  that  of 
the  eye.  The  same  statement  applies  to  the  more  refrangi- 
ble end.  Ritter  discovered  the  extension  of  the  spectrum 
into  the  invisible  region  beyond  the  violet;  and,  in  recent 
times,  this  ultra-violet  emission  has  had  peculiar  interest 
conferred  upon  it  by  the  admirable  researches  of  Professor 
Stokes.  The  complete  spectrum  of  the  sun  consists,  there- 
fore, of  three  distinct  parts:  first,  of  ultra-red  rays  of  high 
heating  power,  but  unsuited  to  the  purposes  of  vision; 
secondly,  of  luminous  rays  which  display  the  succession  of 


RADIATION.  23 

colors,  red,  orange,  yellow,  green,  blue,  indigo,  violet; 
thirdly,  of  ultra-violet  rays  which,  like  the  ultra-red  ones, 
are  incompetent  to  excite  vision,  but  which,  unlike  the 
ultra- red  rays,  possess  a  very  feeble  heating  power.  In 
consequence,  however,  of  their  chemical  energy  these  ultra- 
violet rays  are  of  the  utmost  importance  to  the  organic 
world. 

2.   Origin  and  Character  of  Radiation.     The  Ether. 

When  we  see  a  platinum  wire  raised  gradually  to  a  white 
heat,  and  emitting  in  succession  all  the  colors  of  the  spec- 
trum, we  are  simply  conscious  of  a  series  of  changes  in  the 
condition  of  our  own  eyes.  We  do  not  see  the  actions  in 
which  these  successive  colors  originate,  but  the  mind  irre- 
sistibly infers  that  the  appearance  of  the  colors  corresponds 
to  certain  contemporaneous  changes  in  the  wire.  What  is 
the  nature  of  these  changes?  In  virtue  of  what  condition 
does  the  wire  radiate  at  all?  We  must  now  look  from  the 
wire,  as  a  whole,  to  its  constituent  atoms.  Could  we  see 
those  atoms,  even  before  the  electric  current  has  begun  to 
act  upon  them,  we  should  find  them  in  a  state  of  vibration. 
In  this  vibration,  indeed,  jconsists  such  warmth  as  the  wire 
then  possesses.  Locke  enunciated  this  idea  with  great  pre- 
cision, and  it  has  been  placed  beyond  the  pale  of  doubt  by 
the  excellent  quantitative  researches  of  Mr.  Joule.  "  Heat," 
says  Locke,  "  is  a  very  brisk  agitation  of  the  insensible 
parts  of  the  object,  which  produce  in  us  that  sensation 
from  which  we  denominate  the  object  hot;  so  what  in  onr 
sensations  is  heat  in  the  object  is  nothing  but  motion." 
When  the  electric  current,  still  feeble,  begins  to  pass 
through  the  wire,  its  first  act  is  to  intensify  the  vibrations 
already  existing,  by  causing  the  atoms  to  swing  through 
wider  ranges.  Technically  speaking  the  amplitudes  of  the 
oscillations  are  increased.  The  current  does  this,  however, 
without  altering  the  periods  of  the  old  vibrations,  or  the 
times  in  which  they  were  executed.  But  besides  intensi- 
fying the  old  vibrations  the  current  generates  new  and 
more  rapid  ones,  and  when  a  certain  definite  rapidity  has 
been  attained,  the  wire  begins  to  glow.  The  color  first 
exhibited  is  red,  which  corresponds  to  the  lowest  rate  of 
vibration  of  which  the  eye  is  able  to  take  cognizance.  By 
augmenting  the  strength  of  the  electric  current  more  rapid 
vibrations  are  introduced,  and  orange  rays  appear.  A 


24  FRAGMENTS  OF  SCIENCE. 

quicker  rate  of  vibration  produces  yellow,  a  still  quicker, 
green;  and  by  further  augmenting  the  rapidity,  we  pass 
through  blue,  indigo,  and  violet,  to  the  extreme  ultra- 
violet rays. 

Such  are  the  changes  recognized  by  the  mind  in  the  wire 
itself,  as  concurrent  with  the  visual  changes  taking  place 
in  the  eye.  But  what  connects  the  wire  with  this  organ? 
By  what  means  does  it  send  such  intelligence  of  its  vary- 
ing condition  to  the  optic  nerve?  Heat  being  as  denned  by 
Locke,  "a  very  brisk  agitation  of  the  insensible  parts  of  an 
object,"  it  is  readily  conceivable  that  on  touching  a  heated 
body  the  agitation  may  communicate  itself  to  the  adjacent 
nerves,  and  announce  itself  to  them  as  light  or  heat.  But 
the  optic  nerve  does  not  touch  the  hot  platinum,  and 
hence  the  pertinence  of  the  question,  By  what  agency  are 
the  vibrations  of  the  wire  transmitted  to  the  eye? 

The  answer  to  this  question  involves  one  of  the  most 
important  physical  conceptions  that  the  mind  of  man  has 
yet  achieved  :  the  conception  of  a  medium  filling  space 
and  fitted  mechanically  for  the  transmission  of  the  vibra- 
tions of  light  and  heat,  as  air  is  fitted  for  the  transmission 
of  sound.  This  medium  is  called  the  luminiferous  ether. 
Every  vibration  of  every  atom  of  our  platinum  wire  raises 
in  this  ether  a  wave,  which  speeds  through  it  at  the  rate  of 
186,000  miles  a  second.  The  ether  suffers  no  rupture  of 
continuity  at  the  surface  of  the  eye,  the  inter-molecular 
spaces  of  the  various  humors  are  filled  with  it;  hence  the 
waves  generated  by  the  glowing  platinum  can  cross  these 
humors  and  impinge  on  the  optic  nerve  at  the  back  of  tiie 
eye.*  Thus  the  sensation  of  light  reduces  itself  to  the 
acceptance  of  motion.  Up  to  this  point  we  deal  with  pure 
mechanics  ;  but  the  subsequent  translation  of  the  shock  of 
the  ethereal  waves  into  consciousness  eludes  mechanical 
science.  As  an  oar  dipping  into  the  Cam  generates  sys- 
tems of  waves,  which,  speeding  from  the  center  of  disturb- 
ance, finally  stir  the  sedges  on  the  river's  bank,  so  do  the 
vibrating  atoms  generate  in  the  surrounding  ether  undu- 
lations, which  finally  stir  the  filaments  of  the  retina.  The 
motion  thus  imparted  is  transmitted  with  measurable,  and 
not  very  great  velocity  to  the  brain,  where,  by  a  process 

*  The  action  here  described  is  analogous  to  the  passage  of  sound- 
waves through  thick  felt  whose  interstices  are  occupied  by  air. 


RADIATION.  25 

which  the  science  of  mechanics  does  not  even  tend  to  un- 
ravel, the  tremor  of  the  nervous  matter  is  converted  into 
the  conscious  impression  of  light. 

Darkness  might  then  be  defined  as  ether  at  rest;  light  as 
ether  in  motion.  But  in  reality  the  ether  is  never  at  rest, 
for  in  the  absence  of  light-waves  we  have  heat-waves 
always  speeding  through  it.  In  the  spaces  of  the  universe 
both  classes  of  undulations  incessantly  commingle.  Here 
the  waves  issuing  from  uncounted  centers  cross,  coincide, 
oppose,  and  pass  through  each  other,  without  confusion  or 
ultimate  extinction.  Every  star  is  seen  across  the  entangle- 
ment of  wave-motions  produced  by  all  other  stars.  It  is 
the  ceaseless  thrill  caused  by  those  distant  orbs  collectively 
in  the  ether,  that  constitutes  what  we  call  the  "tempera- 
ture of  space."  As  the  air  of  a  room  accommodates  itself  to 
the  requirements  of  an  orchestra,  transmitting  eacli  vibra- 
tion of  every  pipe  and  string,  so  does  the  inter-stellar  ether 
accommodate  itself  to  the  requirements  of  light  and  heat. 
Its  waves  mingle  in  space  without  disorder,  each  being  en- 
dowed with  an  individuality  as  indestructible  as  if  it  alone 
had  disturbed  the  universal  repose. 

All  vagueness  with  regard  to  the  use  of  the  terms 
"  radiation  "  and  "  absorption  "  will  now  disappear.  Radia- 
tion is  the  communication  of  vibratory  motion  to  the 
ether;  and  when  a  body  is  said  to  be  chilled  by  radiation, 
as  for  example  the  grass  of  a  meadow  on  a  starlight  night, 
the  meaning  is,  that  the  molecules  of  the  grass  have  lost  a 
portion  of  their  motion,  by  imparting  it  to  the  medium  in 
which  they  vibrate.  On  the  other  hand,  the  waves  of 
ether  may  so  strike  against  the  molecules  of  a  body  exposed 
to  their  action  as  to  yield  up  their  motion  to  the  latter; 
and  in  this  transfer  of  the  motion  from  the  ether  to  the 
molecules  consists  the  absorption  of  radiant  heat.  All  the 
phenomena  of  heat  are  in  this  way  reducible  to  inter- 
changes of  motion;  and  it  is  purely  as  the  recipients  or 
the  donors  of  this  motion,  that  we  ourselves  become  con- 
scious of  the  action  of  heat  and  cold. 

3.   The  Atomic  TJieory  in  reference  to  the  Ether. 

The  word  "atoms "has  been  more  than  once  employed 
in  this  discourse.  Chemists  have  taught  us  that  all  mat- 
ter is  reducible  to  certain  elementary  forms  to  which  they 
give  this  name.  These  atoms  are  endowed  with  powers  of 


26  FRAGMENTS  OF  SCIENCE. 

mutual  attraction,  and  under  suitable  circumstances  they 
coalesce  to  form  compounds.  Tims  oxygen  and  hydrogen 
are  elements  when  separate,  or  merely  mixed,  but  they 
may  be  made  to  combine  so  as  to  form  molecules,  each  con- 
sisting of  two  atoms  of  hydrogen  and  one  of  oxygen.  In 
this  condition  they  constitute  water.  So  also  chlorine  and 
sodium  are  elements,  the  former  a  pungent  gas,  the  latter 
a  soft  metal;  and  they  unite  together  to  form  chloride  of 
sodium  or  common  salt.  In  the  same  way  the  element 
nitrogen  combines  with  hydrogen,  in  the  proportion  of 
one  atom  of  the  former  to  three  of  the  latter,  to  form  am- 
monia. Picturing  in  imagination  the  atoms  of  elementary 
bodies  as  little  spheres,  the  molecules  of  compound  bodies 
must  be  pictured  as  groups  of  such  spheres.  This  is  the 
atomic  theory  as  Dalton  conceived  it.  Now  if  this  theory 
have  any  foundation  in  fact,  and  if  the  theory  of  an  ether 
pervading  space,  and  constituting  the  vehicle  of  atomic 
motion,  be  founded  in  fact,  it  is  surely  of  interest  to  ex- 
amine whether  the  vibrations  of  elementary  bodies  are 
modified  by  the  act  of  combination — whether  as  regards 
radiation  and  absorption,  or,  in  other  words,  whether  as 
regards  the  communication  of  motion  to  the  ether,  and  the 
acceptance  of  motion  from  it,  the  deportment  of  the 
uncombined  atoms  will  be  different  from  that  of  the 
combined. 

4.  Absorption  of  Radiant  Heat  by  Gases. 

We  have  now  to  submit  these  considerations  to  the  only 
test  by  which  they  can  be  tried,  namely,  that  of  experi- 
ment. An  experiment  is  well  defined  as  a  question  put  to 
Nature;  but,  to  avoid  the  risk  of  asking  amiss,  we  ought 
to  purify  the  question  from  all  adjuncts  which  do  not 
necessarily  belong  to  it.  Matter  has  been  shown  to  be 
composed  of  elementary  constituents,  by  the  compounding 
of  which  all  its  varieties  are  produced.  But,  besides  the 
chemical  unions  which  they  form,  both  elementary  and 
compound  bodies  can  unite  in  another  and  less  intimate 
way.  Gases  and  vapors  aggregate  to  liquids  and  solids, 
without  any  change  of  their  chemical  nature.  We  do  not 
yet  know  how  the  transmission  of  radiant  heat  may  be 
affected  by  the  entanglement  due  to  cohesion;  and,  as  our 
object  now  is  to  examine  the  influence  of  chemical  union 
alone,  we  shall  render  our  experiments  more  pure  by  liber- 


RADIATION.  27 

ating  the  atoms  and  molecules  entirely  from  the  bonds  of 
cohesion,  and  employing  them  in  the  gaseous  or  vaporous 
form. 

Let  us  endeavor  to  obtain  a  perfectly  clear  mental  image 
of  the  problem  now  before  us.  Limiting  in  the  first  place 
our  inquiries  to  the  phenomena  of  absorption,  we  have  to 
picture  a  succession  of  waves  issuing  from  a  radiant  source 
and  passing  th rough  a  gas;  some  of  them  striking  against 
the  gaseous  molecules  and  yielding  up  their  motion  to  the 
latter;  others  gliding  round  the  molecules,  or  passing 
through  the  intermolecular  spaces  without  apparent  hin- 
drance. The  problem  before  us  is  to  determine  whetlver 
such  free  molecules  have  any  power  whatever  to  stop  the 
waves  of  heat;  and  if  so,  whether  different  molecules 
possess  this  power  in  different  degrees. 

In  examining  the  problem  let  us  fall  back  upon  an  actual 
piece  of  work,  choosing  as  the  source  of  our  heat  waves  a 
plate  of  copper,  against  the  back  of  which  a  steady  sheet 
of  flame  is  permitted  to  play.  On  emerging  from  the  cop- 
per, the  waves,  in  the  first  instance,  pass  through  a  space 
devoid  of  air,  and  then  enter  a  hollow  glass  cylinder,  three 
feet  long  and  three  inches  wide.  The  two  ends  of  this 
cylinder  are  stopped  by  two  plates  of  rock-salt,  a  solid  sub- 
stance which  offers  a  scarcely  sensible  obstacle  to  the  pas- 
sage of  the  calorific  waves.  After  passing  through  the  tube, 
the  radiant  heat  falls  upon  the  anterior  face  of  a  thermo- 
electric pile,*  which  instantly  converts  the  heat  into  an 
electric  current.  This  current  conducted  round  a  magnetic 
needle  deflects  it,  and  the  magnitude  of  the  deflection  is  a 
measure  of  the  heat  falling  upon  the  pile.  This  famous 
instrument,  and  not  an  ordinary  thermometer,  is  what  we 
shall  use  in  these  inquiries,  but  we  shall  use  it  in  a  some- 
what novel  way.  As  long  as  the  two  opposite  faces  of  the 
thermo-electric  pile  are  kept  at  the  same  temperature,  no 
matter  how  high  that  may  be,  there  is  no  current  gener- 
ated. The  current  is  a  consequence  of  a  difference  of  tem- 
perature between-  the  two  opposite  faces  of  the  pile. 
Hence,  if  after  the  anterior  face  has  received  the  heat  from 
our  radiating  source,  a  second  source,  which  we  may  call 
the  compensating  source,  be  permitted  to  radiate  against 
the  posterior  face,  this  latter  radiation  will  tend  to  neu- 

*  In  the  Appendix  to  the  first  chapter  of  "  Heat  as  a  Mode  of  Mo- 
tion," the  construction  of  the  thermo-electric  pile  is  fully  explained. 


23  FRAGMENTS  OF  SCIENCE. 

tralize  the  former.  When  the  neutralization  is  perfect, 
the  magnetic  needle  connected  with  the  pile  is  no  longer 
deflected,  but  points  to  the  zero  of  the  graduated  circle 
over  which  it  hangs. 

And  now  let  us  suppose  the  glass  tube,  through  which 
the  waves  from  the  heated  plate  of  copper  are  passing,  to 
he  exhausted  by  an  air  pump,  the  two  sources  of  heat  act- 
ing at  the  same  time  on  the  two  opposite  faces  of  the  pile. 
When  by  means  of  an  adjusting  screen,  perfectly  equal 
quantities  of  heat  are  imparted  to  the  two  faces,  the  needle 
points  to  zero.  Let  any  gas  be  now  permitted  to  enter  the 
exhausted  tube;  if  its  molecules  possess  any  power  of  in- 
tercepting the  calorific  waves,  the  equilibrium  previously 
existing  will  be  destroyed,  the  compensating  source  will 
triumph,  and  a  deflection  of  the  magnetic  needle  will  be 
the  immediate  consequence.  From  the  deflections  thus 
produced  by  different  gases,  we  can  readily  deduce  the 
relative  amounts  of  wave-motion  which  their  molecules 
intercept. 

In  this  way  the  substances  mentioned  in  the  following 
table  were  examined,  a  small  portion  only  of  each  being 
admitted  into  the  glass  tube.  The  quantity  admitted  in 
each  case  was  just  sufficient  to  depress  a  column  of  mer- 
cury associated  with  the  tube  one  inch;  in  other  words, 
the  gases  were  examined  at  a  pressure  of  one-thirtieth  of 
an  atmosphere.  The  numbers  in  the  table  express  the 
relative  amounts  of  wave-motion  absorbed  by  the  respective 
gases,  the  quantity  intercepted  by  atmospheric  air  being 
taken  as  unity.  • 

RADIATION    THROUGH  GASES. 

Relative 
Name  of  gas.  absorption. 

Air 1 

Oxygen 1 

Nitrogen 1 

Hydrogen .  1 

Carbonic  oxide 750 

Carbonic  acid 972 

Hydrochloric  acid 1,005 

Nitric  oxide 1,590 

Nitrous  oxide , 1,860 

Sulphide   of  hydrogen 2,100 

Ammonia , 5,460 

Olefiant  gas 6,030 

Sulphurous  acid , ,..,..,...  6,480, 


&ADIATION.  29 

Every  gas  in  this  table  is  perfectly  transparent  to  light, 
that  is  to  say,  all  waves  within  the  limits  of  the  visible 
spectrum  pass  through  it  without  obstruction;  but  for  the 
waves  of  slower  period,  emanating  from  our  heated  plate 
of  copper,  enormous  differences  of  absorptive  power  are 
manifested.  These  differences  illustrate  in  the  most  un- 
expected manner  the  influence  of  chemical  combination, 
Thus  the  elementary  gases,  oxygen,  hydrogen,  and  nitro- 
gen, and  the  mixture  atmospheric  air,  prove  to  be  prac- 
tical vacua  to  the  rays  of  heat;  for  every  ray,  or,  more 
strictly  speaking,  for  every  unit  of  wave-motion,  which 
any  one  of  them  intercepts,  perfectly  transparent  ammonia 
intercepts  5,460  units,  defiant  gas  6,030  units,  while  sul- 
phurous acid  gas  absorbs  6,480  units.  What  becomes  of 
the  wave-motion  thus  intercepted?  It  is  applied  to  the 
heating  of  the  absorbing  gas.  Through  air,  oxygen,  hydro- 
gen, and  nitrogen,  the  waves  of  ether  pass  without 
absorption,  and^  these  gases  are  not  sensibly  changed  in 
temperature  by  the  most  powerful  calorific  rays.  The 
position  of  nitrous  oxide  in  the  foregoing  table  is  worthy 
of  particular  notice.  In  this  gas  we  have  the  same  atoms 
in  a  state  of  chemical  union,  that  exist  uncombined  in  tLe 
atmosphere;  but  the  absorption  of  the  compound  is  1,800 
times  that  of  air. 

5.  Formation  of  Invisible  Foci. 

This  extraordinary  deportment  of  the  elementary  gases 
naturally  directed  attention  to  elementary  bodies  in  other 
states  of  aggregation.  Some  of  Melloni's  results  now  at- 
tained a  new  significance.  This  celebrated  experimenter 
had  found  crystals  of  sulphur  to  be  highly  pervious  to 
xadiant  heat;  he  had  also  proved  that  lampblack,  and 
black  glass  (which  owes  its  blackness  to  the  element  car- 
ibon)  were  to  a  considerable  extent  transparent  to  calorific 
rays  of  low  refrangibility.  These  facts,  harmonizing  so 
istrikingly  with  the  deportment  of  the  simple  gases,  sug- 
gested further  inquiry.  Sulphur  dissolved  in  bisulphide  of 
<earbon  was  found  almost  perfectly  diathermic.  The  dense 
.•and  deeply-colored  element  bromine  was  examined,  and 
found  competent  to  cut  off  the  light  of  our  most  brilliant 
flames,  while  it  transmitted  the  invisible  calorific  rays  with 
icxtreme  freedom.  Iodine,  the  companion  element  of  bro- 
mine, was  next  thought  of,  but  it  was  found  impracticable 


30  FRAGMENTS  OF  SCIENCE. 

to  examine  the  substance  in  its  nsnal  solid  condition.  It 
however  dissolves  freely  in  bisulphide  of  carbon,  There  is 
no  chemical  union  between  the  liquid  and  the  iodine;  it  is 
simply  a  case  of  solution,  in  which  the  uncombined  atoms 
of  the  element  can  act  upon  the  radiant  heat.  When  per- 
mitted to  do  so,  it' was  found  that  a  layer  of  dissolved 
iodine,  sufficiently  opaque  to  cut  off  the  light  of  the  mid- 
day sun,  was  almost  absolutely  transparent  to  the  invisible 
calorific  rays.* 

By  prismatic  analysis  Sir  William  llerschel  separated 
the  luminous  from  the  non-luminous  rays  of  the  sun,  and 
he  also  sought  to  render  the  obscure  rays  visible  by  con- 
centration. Intercepting  the  luminous  portion  of  his 
spectrum  he  brought^  by  a  converging  lens,  the  ultra-red 
rays  to  a  focus,  but  by  this  condensation  he  obtained  no 
light.  The  solution  of  iodine  offers  a  means  of  filtering 
the  solar  beam,  or  failing  it,  the  beam  of  the  electric  lamp, 
which  renders  attainable  far  more  powerful  foci  of  invisi- 
ble rays  than  could  possibly  be  obtained  by  the  method  of 
Sir  William  Herschel.  For  to  form  his  spectrum  he  was 
obliged  to  operate  upon  solar  light  which  had  passed 
through  a  narrow  slit  or  through  a  small  aperture,  the 
amount  of  the  obscure  heat  being  limited  by  this  circum- 
stance. But  with  our  opaque  solution  we  may  employ  the 
entire  surface  of  the  largest  lens,  and  having  thus  con- 
verged the  rays,  luminous  and  non-luminous,  we  can 
intercept  the  former  by  the  iodine,  and  do  what  we  please 
with  the  latter.  Experiments  of  this  character,  not  only 
with  the  iodine  solution,  but  also  with  black  glass  and 
layers  of  lampblack,  were  publicly  performed  at  the  Royal 
Institution  in  the  early  part  of  1862,  and  the  effects  at  the 
foci  of  invisible  rays,  then  obtained,  were  such  as  had 
never  been  witnessed  previously. 

In  the  experiments  here  referred  to,  glass  lenses  were 
employed  to  concentrate  the  rays.  But  glass,  though 
highly  transparent  to  the  luminous,  is  in  a  high  degree 
opaque  to  the  invisible  heat-rays  of  the  electric  lamp,  and 
hence  a  large  portion  of  those  rays  was  intercepted  by  the 
glass.  The  obvious  remedy  here  is  to  employ  rock-salt 
lenses  instead  of  glass  ones,  or  to  abandon  the  use  of  lenses 

*  Professor  Dewar  has  recently  succeeded  in  producing  a  medium 
highly  opaque  to  light,  aud  highly  transparent  to  obscure  heat,  by 
fusing  together  sulphur  and  iodine! 


RADIATION.  31 

wholly,  and  to  concentrate  the  rays  by  a  metallic  mirror. 
Both  of  these  improvements  have  been  introduced,  and,  as 
anticipated,  the  invisible  foci  have  been  thereby  rendered 
more  intense.  The  mode  of  operating  remains  however 
the  same,  in  principle,  as  that  made  known  in  1862.  It 
was  then  found  that  an  instant's  exposure  of  the  face  of 
the  thermo-electric  pile  to  the  focus  of  invisible  rays 
dashed  the  needles  of  a  coarse  galvanometer  violently  aside. 
It  is  now  found  that  on  substituting  for  the  face  of  the 
thermo-electric  pile  a  combustible  body,  the  invisible  rays 
are  competent  to  set  that  body  on  fire. 

6.    Visible  and  Invisible  Rays  of  the  Electric   Light. 

We  have  next  to  examine  what  proportion  the  non- 
luminous  rays  of  the  electric  light  bear  to  the  luminous 
ones.  This  the  opaque  solution  of  iodine  enables  us  to  do 
with  an  extremely  close  approximation  to  the  truth.  The 
pure  bisulphide  of  carbon,  which  is  the  solvent  of  the 
iodine,  is  perfectly  transparent  to  the  luminous,  and  almost 
perfectly  transparent  to  the  dark  rays  of  the  electric  lamp. 
Supposing  the  total  radiation  of  the  lamp  to  pass  through 
the  transparent  bisulphide,  while  through  the  solution  of 
iodine  only  the  dark  rays  are  transmitted.  If  we  deter- 
mine, by  means  of  a  thermo-electric  pile,  the  total  radia- 
tion, and  deduct  from  it  the  purely  obscure,  we  obtain  the 
value  of  the  purely  luminous  emission.  Experiments  per- 
formed in  this  way  prove  that  if  all  the  visible  rays  of  the 
electric  light  were  converged  to  a  focus  of  dazzling  bril- 
liancy, its  heat  would  only  be  one-eighth  of  that  produced 
at  the  unseen  focus  of  the  invisible  rays. 

Exposing  his  thermometers  to  the  successive  colors  of  the 
solar  spectrum,  Sir  William  Herschel  determined  the  heat- 
ing power  of  each,  and  also  that  of  the  region  beyond  the 
extreme  red.  Then  drawing  a  straight  line  to  represent 
the  length  of  the  spectrum,  he  erected,  at  various  points, 
perpendiculars  to  represent  the  calorific  intensity  existing 
at  those  points.  Uniting  the  ends  of  all  his  perpendicu- 
lars, he  obtained  a  curve  which  showed  at  a  glance  the 
manner  in  which  the  heat  was  distributed  in  the  solar  spec- 
trum. Professor  Miiller  of  Freiburg,  with  improved  in- 
struments, afterward  made  similar  experiments,  and  con- 
structed a  more  accurate  diagram  of  the  same  kind.  We 
have  now  to  examine  the  distribution  of  heat  in  the  spec- 


32  FRAGMENTS  OP  SCIENCE. 

trum  of  the  electric  light;  and  for  this  purpose  we  shall 
employ  a  particular  form  of  the  thermo-electric  pile, 
devised  by  Melloni.  Its  face  is  a  rectangle,  which  by 
means  of  movable  side-pieces  can  be  rendered  as  narrow  as 
desired.  We  can,  for  example,  have  the  face  of  the  pile 
the  tenth,  the  hundredth,  or  even  the  thousandth  of  an 
inch  in  breadth.  By  means  of  an  endless  screw,  this  linear 
thermo-electric  pile  may  be  moved  through  the  entire 
spectrum,  from  the  violet  to  the  red,  the  amount  of  heat 
falling  upon  the  pile  at  every  point  of  its -march  being 
declared  by  a  magnetic  needle  associated  with  the  pile. 

When  this  instrument  is  brought  up  to  the  violet  end  of 
the  spectrum  of  the  electric  light,  the  heat  is  found  to  be 
insensible.  As  the  pile  is  gradually  moved  from  the  violet 
end  toward  the  red,  heat  soon  manifests  itself,  augmenting 
as  we  approach  the  red.  Of  all  the  colors  of  the  visible 
spectrum  the  red  possesses  the  highest  heating  power. 
On  pushing  the  pile  into  the  dark  region  beyond  the  red, 
the  heat,  instead  of  vanishing,  rises  suddenly  and  enor- 
mously in  intensity,  until  at  some  distance  beyond  the  red  it 
attains  a  maximum.  Moving  the  pile  still  forward,  the 
thermal  power  falls,  somewhat  more  rapidly  than  it  rose. 
It  then  gradually  shades  away,  but,  for  a  distance  beyond 
the  red  greater  than  the  length  of  the  whole  visible  spec- 
trum, signs  of  heat  may  be  detected. 

Drawing  a  datum  line,  and  erecting  along  it  perpendicu- 
lars, proportional  in  length  to  the  thermal  intensity  at  the 
respective  points,  we  obtain  the  extraordinary  curve,  shown 
on  the  opposite  page,  which  exhibits  the  distribution  of 
heat  in  the  spectrum  of  the  electric  light.  In  the  region 
of  dark  rays,  beyond  the  red,  the  curve  shoots  up  to  B,  in 
a  steep  and  massive  peak — a  kind  of  Matterhorn  of  heat, 
which  dwarfs  the  portion  of  the  diagram  ODE,  represent- 
ing the  luminous  radiation.  Indeed  the  idea  forced  upon 
the  mind  by  this  diagram  is  that  the  light  rays  are  a  mere 
insignificant  appendage  to  the  heat-rays  represented  by  the 
area  A  B  c  D,  thrown  in,  as  it  were,  by  nature  for  the  pur- 
pose of  vision. 

The  diagram  drawn  by  Professor  Miiller  to  represent  the 
distribution  of  heat  in  the  solar  spectrum  is  not  by  any 
means  so  striking  as  that  just  described,  and  the  reason, 
doubtless,  is  that  prior  to  reaching  the  earth  the  solar  rays 
have  to  traverse  our  atmosphere.  By  the  aqueous  vapor 


RADIATION. 


34  FRAGMENTS  OF  SCIENCE. 

there  diffused,  the  summit  of  the  peak  representing  the 
sun's  invisible  radiation  is  cut  off.  A  similar  lowering  of  the 
mountain  of  invisible  heat  is  observed  when  the  rays  from 
the  electric  light  are  permitted  to  pass  through  a  film  of 
water,  which  acts  upon  them  as  the  atmospheric  vapor  acts 
upon  the  rays  of  the  sun. 

7.   Combustion  by  Invisible  Rays. 

The  sun's  invisible  rays  far  transcend  the  visible  ones  in 
heating  power,  so  that  if  the  alleged  performances  of 
Archimedes  during  the  siege  of  Syracuse  hud  any  founda- 
tion in  fact  the  dark  solar  rays  would  have  been  the  phi- 
losopher's chief  agents  of  combustion.  On  a  small  scale  we 
can  readily  produce,  with  the  purely  invisible  rays  of  the 
electric  light,  all  that  Archimedes  is  said  to  have  performed 
with  the  sun's  total  radiation.  Placing  behind  the  electric 
light  a  small  concave  mirror,  the  rays  are  converged,  the 
cone  of  reflected  rays  and  their  point  of  convergence  being 
rendered  clearly  visible  by  the  dust  always  floating  in  the 
air.  Placing  between  the  luminous  focus  and  the  source 
of  rays  our  solution  of  iodine,  the  light  of  the  cone  is  en- 
tirely cut  away;  but  the  intolerable  heat  experienced  when 
the  hand  is  placed,  even  for  a  moment,  at  the  dark  focus, 
shows  that  the  calorific  rays  pass  unimpeded  through  the 
opaque  solution. 

Almost  anything  that  ordinary  fire  can  effect  may  be 
accomplished  at  the  focus  of  invisible  rays;  the  air  at  the 
focus  remaining  at  the  same  time  perfectly  cold,  on  account 
of  its  transparency  to  the  heat-rays.  An  air  thermometer, 
with  a  hollow  rock-salt  bulb,  would  be  unaffected  by  the 
heat  of  the  focus:  there  would  be  no  expansion,  and  in  the 
open  air  there  is  no  convection.  The  ether  at  the  focus, 
and  not  the  air,  is  the  substance  in  which  the  heat  is  em- 
bodied. A  block  of  wood,  placed  at  the  focus,  absorbs  the 
heat,  and  dense  volumes  of  smoke  rise  swiftly  upward, 
showing  the  manner  in  which  the  air  itself  would  rise,  if 
the  invisible  rays  were  competent  to  heat  it.  At  the  per- 
fectly dark  focus  dry  paper  is  instantly  inflamed;  chips  of 
wood  arespeedily  burned  up;  lead,  tin,  and  zinc  are  fused; 
and  disks  of  charred  paper  are  raised  to  vivid  incandes- 
cence. It  might  be  supposed  that  the  obscure  rays  would 
show  no  preference  for  black  over  white;  but  they'do  show 
a  preference,  and  to  obtain  rapid  combustion,  the  body,  if 


RADIATION.  35 

not  already  Black,  ought  to  be  blackened.  When  metals 
are  to  be  burned,  it  is  necessary  to  blacken  or  otherwise 
tarnish  them,  £O  as  to  diminish  their  reflective  power. 
Blackened  zinc  foil,  when  brought  into  the  focus  of  invisi- 
ble rays,  is  instantly  caused  to  blaze,  and  burns  with  its 
peculiar  purple  light.  Magnesium  wire  flattened,  or  tar- 
nished magnesium  ribbon,  also  bursts  into  flame.  Pieces 
of  charcoal  suspended  in  a  receiver  full  of  oxygen  are  also 
set  on  fire  when  the  invisible  focus  falls  upon  them;  the 
dark  rays  after  having  passed  through  the  receiver,  still 
possessing  sufficient  power  to  ignite  the  charcoal,  and  thus 
initiate  the  attack  of  the  oxygen.  If,  instead  of  being 
plunged  in  oxygen,  the  charcoal  be  suspended  in  vacuo,  it 
immediately  glows  at  the  place  where  the  focus  falls. 

8.   Transmutation  of  Rays:  *  Calorescence. 

Eminent  experimenters  were  long  occupied  in  demon- 
strating the  substantial  identity  of  light  and  radiant  heat, 
and  we  have  now  the  means  of  offering  a  new  and  striking 
proof  of  this  identity.  A  concave  mirror  produces,  beyond 
the  object  which  it  reflects,  an  inverted  and  magnified 
image  of  the  object.  Withdrawing,  for  example,  our 
iodine  solution,  an  intensely  luminous  inverted  image  of 
the  carbon  points  of  the  electric  light  is  formed  at  the 
focus  of  the  mirror  employed  in  the  foregoing  experiments. 
When  the  solution  is  interposed,  and  the  light  is  cut  away, 
what  becomes  of  this  image?  It  disappears  from  sight;  but 
an  invisible  thermograph  remains,  and  it  is  only  the  pecul- 
iar constitution  of  our  eyes  that  disqualifies  us  from  seeing 
the  picture  formed  by  the  calorific  rays.  Falling  on  white 
paper,  the  image  chars  itself  out:  falling  on  black  paper, 
two  holes  are  pierced  in  it,  corresponding  to  the  images  of 
the  two  coke  points:  but  falling  on  a  thin  plate  of  carbon 
in  vacuo,  or  upoii  a  thin  sheet  of  platinized  platinum, 
either  in  vacuo  or  in  air,  radiant  heat  is  converted  into 
light,  and  the  image  stamps  itself  in  vivid  incandescence 
upon  both  the  carbon  and  the  metal.  Results  similar  to 
those  obtained  with  the  electric  light  have  also  been  ob- 
tained with  the  invisible  rays  of  the  lime-light  and  of  the 
sun. 

Before  a   Cambridge  audience  it  is  hardly  necessary  to 

*I  borrow  this  terra  from  Professor  Chain's,  "Philosophical  Maga- 
zine," vol.  xii.,  p.  521. 


36  FRAGMENTS  OF  SCIENCE. 

refer  to  the  excellent  researches  of  Professor  Stokes  at  the 
opposite  end  of  the  spectrum.  The  above  results  consti- 
tute a  kind  of  complement  to  his  discoveries.  Professor 
Stokes  named  the  phenomena  which  he  has  discovered  and 
investigated  Fluorescence;  for  the  new  phenomena  here 
described  I  have  proposed  the  term  Calorescence.  He,  by 
the  interposition  of  a  proper  medium,  so  lowered  the  re- 
frangibility  of  the  ultra-violet  rays  of  the  spectrum  as  to 
render  them  visible.  Here,  by  the  interposition  of  the 
platinum  foil,  the  refrangibility  of  the  ultra-red  rays  is  so 
exulted  as  to  render  them  visible.  Looking  through  a 
prism  at  the  incandescent  image  of  the  carbon  points,  the 
light  of  the  image  is  decomposed,  and  a  complete  spectrum 
is  obtained.  The  invisible  rays  of  the  electric  light,  re- 
molded by  the  atoms  of  the  platinum,  shine  thus  visibly 
forth;  ultra-red  rays  being  converted  into  red,  orange, 
yellow,  green,  blue,"  indigo,  violet,  and  ultra-violet  ones. 
Could  we,  moreover,  raise  the  original  source  of  rays  to  a 
sufficiently  high  temperature,  we  might  not  only  obtain 
from  the  dark  rays  of  such  a  source  a  single  incandescent 
image,  but  from  the  dark  rays  of  this  image  we  might 
obtain  a  second  one,  from  the  dark  rays  of  the  second  a 
third,  and  so  on — a  series  of  complete  images  and  spectra 
being  thus  extracted  from  the  invisible  emission  of  the 
primitive  source.* 

*0n  investigating  the  calorescence  produced  by  rays  transmitted 
through  glasses  of  various  colors,  it  was  found  that  in  the  case  of 
certain  specimens  of  blue  glass,  the  platinum  foil  glowed  with  a 
pink  or  purplish  light.  The  effect  was  not  subjective,  and  consider- 
ations of  obvious  interest  are  suggested  by  it.  Different  kinds  of 
black  glass  differ  notably  as  to  their  power  of  transmitting  radiant 
heat.  When  thin,  some  descriptions  tint  the  sun  with  a  greenish 
hue:  others  make  it  appear  a  glowing  red  without  any  trace  of  green. 
The  latter  are  far  more  diathermic  than  the  former.  In  fact,  carbon 
when  perfectly  dissolved  and  incorporated  with  a  good  white  glass, 
is  highly  transparent  to  the  calorific  rays,  and  by  employing  it  as  an 
absorbent  the  phenomena  of  "calorescence"  may  be  obtained, 
though  in  a  less  striking  form  than  with  the  iodine.  The  black 
glass  chosen  for  thermometers,  and  intended  to  absorb  completely 
the  solar  heat,  may  entirely  fail  in  this  object,  if  the  glass  in  which 
the  carbon  is  incorporated  be  colorless.  To  render  the  bulb  of  a 
thermometer  a  perfect  absorbent,  the  glass  ought  in  the  first  instance 
to  be  green.  Soon  after  the  discovery  of  fluorescence  the  late  Dr. 
William  Allen  Miller  pointed  to  the  lime-light  as  an  illustration  of 
exalted  refrangibility.  Direct  experiments  have  since  entirely  con- 
firmed the  view  expressed  at  page  210  of  his  wprk  on  "  Chemistry." 
published  in  1855, 


RADIATION.  37 

9.  Deadness  of  the  Optic  Nerve  to  the  Calorific  Rays. 

The  layer  of  iodine  used  in  the  foregoing  experiments 
intercepted  the  rays  of  the  noonday  sun.  No  trace  of 
light  from  the  electric  lamp  was  visible  in  the  darkest 
room,  even  when  a  white  screen  was  placed  at  the  focus  of 
the  mirror  employed  to  concentrate  the  light.  It  was 
thought,  however,  that  if  the  retina  itself  were  brought 
into  the  focus  the  sensation  of  light  might  be  experienced. 
The  danger  of  this  experiment  was  twofold.  If  the  dark 
rays  were  absorbed  in  a  high  degree  by  the  humors  of  the 
eye  the  albumen  of  the  humors  might  coagulate  along  the 
line  of  the  rays.  If,  on  the  contrary,  no  such  high  absorp- 
tion took  place,  the  rays  might  reach  the  retina  with  a 
force  sufficient  to  destroy  it.  To  test  the  likelihood  of 
these  results,  experiments  were  made  on  water  and  on  a 
solution  of  alum,  and  they  showed  it  to  be  very  improbable 
that  in  the  brief  time  requisite  for  an  experiment  any 
serious  damage  could  be  done.  The  eye  was  therefore 
caused  to  approach  the  dark  focus,  no  defense,  in  the  first 
instance,  being  provided;  but  the  heat,  acting  upon  the 
parts  surrounding  the  pupil,  could  not  be  borne.  An 
aperture  was  therefore  pierced  in  a  plate  of  metal,  and  the 
eye,  placed  behind  the  aperture,  was  caused  to  approach 
the  point  of  convergence  of  invisible  rays.  The  focus  was 
attained,  first  by  the  pupil  and  afterward  by  the  retina. 
Removing  the  eye,  but  permitting  the  plate  of  metal  to 
remain,  a  sheet  of  platinum  foil  was  placed  in  the  position 
occupied  by  the  retina  a  moment  before.  The  platinum 
became  red-hot.  No  sensible  damage  was  done  to  the  eye 
by  this  experiment;  no  impression  of  light  was  produced; 
the  optic  nerve  was  not  even  conscious  of  heat. 

But  the  humors  of  the  eye  are  known  to  be  highly  im- 
pervious to  the  invisible  calorific  rays,  and  the  question 
therefore  arises,  "  Did  the  radiation  in  the  foregoing  ex- 
periment reach  the  retina  at  all?"  The  answer  is,  that  the 
rays  were  in  part  transmitted  to  the  retina,  and  in  part 
absorbed  by  the  humors.  Experiments  on  the  eye  of  an  ox 
showed  that  the  proportion  of  obscure  rays  which  reached 
the  retina  amounted  to  18  per  cent,  of  the  total  radiation; 
while  the  luminous  emission  from  the  electric  light 
amounts  to  no  more  than  10  per  cent,  of  the  same  total. 
Were  the  purely  luminous  rays  of  the  electric  lamp  con- 


38  PR  A  QMENTS  OF  SCIENCE. 

verged  by  our  mirror  to  a  focus,  there  can  be  no  doubt  as  to 
the  fate  of  a  retina  placed  there.  Its  ruin  would  be  inevi- 
table; and  yet 'this  would  be  accomplished  by  an  amount 
of  wave-motion  but  little  more  than  half  of  that  which  the 
retina,  without  exciting  consciousness,  bears  at  the  focus 
of  invisible  rays. 

This  subject  will  repay  a  moment's  further  attention. 
At  a  common  distance  of  a  foot  the  visible  radiation  of  the 
electric  light  employed  in  these  experiments  is  800  times 
the  light  of  a  candle.  At  the  same  distance,  the  portion 
of  the  radiation  of  the  electric  light  which  reaches  the 
retina,  but  fails  to  excite  vision,  is  about  1,500  times  the 
luminous  radiation  of  the  candle.*  But  a  candle  on  a 
clear  night  can  readily  be  seen  at  a  distance  of  a  mile,  its 
light  at  this  distance  being  less  than  ^ovoV.innr  °f  ^ts  lig'lfc 
at  the  distant  of  a  foot.  Hence,  to  make  the  candle-light 
a  mile  off  equal  in  power  to  the  non-luminous  radiation 
received  from  the  electric  light  at  a  foot  distance,  its  inten- 
sity would  have  to  be  multiplied  by  1,500x20,000,000,  or 
by  thirty  thousand  millions.  Thus  the  thirty  thousand 
millionth  part  of  the  invisible  radiation  from  the  electric 
light,  received  by  the  retina  at  the  distance  of  a  foot, 
would,  if  slightly  changed  in  character,  be  amply  sufficient 
to  provoke  vision.  Nothing  could  more  forcibly  illustrate 
that  special  relationship  supposed  by  Melloni  and  others  to 
subsist  between  the  optic  nerve  and  the  oscillating  periods 
of  luminous  bodies.  The  optic  nerve  responds,  as  it  were, 
to  the  waves  with  which  it  is  in  consonance,  while  it 
refuses  to  be  excited  by  others  of  almost  infinitely  greater 
energy,  whose  periods  of  recurrence  are  not  in  unison  with 
its  own. 

10.  Persistence  of  Rays. 

At  an  early  part  of  this  lecture  it  was  affirmed,  that 
when  a  platinum  wire  was  gradually  raised  to  a  state  of 
high  incandescence,  new  rays  were  constantly  added,  while 
the  intensity  of  the  old  ones  was  increased.  Thus,  in  Dr. 
Draper's  experiments,  the  rise  of  temperature  that  gener- 
ated the  orange,  yellow,  green,  and  blue  augmented  the 
intensity  of  the  red.  What  is  true  of  the  red  is  true  of 

*It  will  be  borne  in  mind  that  the  heat  which  any  ray,  luminous 
or  non-luminous,  is  competent  to  generate  is  the  true  measure  of  the 
energy  of  the  ray. 


RADIATION.  39 

every  other  fay  of  the  spectrum,  visible  and  invisible.  We 
cannot  indeed  see  the  augmentation  of  intensity  in  the 
region  beyond  the  red,  but  we  can  measure  it  and  express 
it  numerically.  With  this  view  the  following  experiment 
was  performed:  A  spiral  of  platinum  wire  was  surrounded 
by  a  small  glass  globe  to  protect  it  from  cm-rents  of  air; 
through  an  orifice  in  the  globe  the  rays  could  pass  from 
the  spiral  and  fall  afterward  upon  a  thermo-electric  pile. 
Placing  in  front  of  the  orifice  an  opaque  solution  of  iodine, 
the  platinum  was  gradually  raised  from  a  low  dark  heat  to 
the  fullest  incandescence,  with  the  following  results: 

Appearance  Energy  of  obscure 

of  spiral.  radiation. 

Dark 1 

Dark,  but  hotter 3 

Dark,  but  still  hotter 5 

Dark,  but  still  hotter 10 

Feeble   red 19 

Dullred 25 

Red 37 

Full  red 62 

Orange 89 

Bright  orange 144 

Yellow 202 

White 276 

Intense  white 440 

Thus  the  augmentation  of  the  electric  current,  which 
raises  the  wire  from  its  primitive  dark  condition  to  an  in- 
tense white  heat,  exalts  at  the  same  time  the  energy  of  the 
obscure  radiation,  until  at  the  end  it  is  fully  440  times 
what  it  was  at  the  beginning. 

What  has  been  here  proved  true  of  the  totality  of  the 
ultra-red  rays  is  true  for  each  of  them  singly.  Placing  our 
linear  thermo-electric  pile  in  any  part  of  the  ultra-red  spec- 
trum, it  may  be  proved  that  a  ray  once  emitted  continues 
to  be  emitted  with  increased  energy  as  the  temperature  is 
augmented.  The  platinum  spiral,  so  often  referred  to, 
being  raised  to  whiteness  by  an  electric  current,  a  brilliant 
spectrum  was  formed  from  its  light.  A  linear  thermo- 
electric pile  was  placed  in  the  region  of  obscure  rays  be- 
yond the  red,  and  by  diminishing  the  current  the  spiral 
was  reduced  to  a  low  temperature.  It  was  then  caused  to 
pass  through  various  degrees  of  darkness  and  incandes- 
cence, with  the  following  results: 


40  •   FRAGMENTS  OF  SCIENCE. 

Appearance  Energy  of 

of  spiral.  obscure  rays. 

Dark 1 

Dark 6 

Faint  red » * 10 

Dull  red 13 

Red 18 

Full  red 27 

Orange 60 

Yellow 93 

White 122 

Here,  as  in  the  former  case,  the  dark  arid  bright  radi- 
ations reached  their  maximum  together;  as  the  one  aug- 
mented, the  other  augmented,  until  at  last  the  energy  of 
the  obscure  rays  of  the  particular  refrangibility  here  chosen 
became  122  times  what  it  was  at  first.  To  reach  a  white 
heat  the  wire  has  to  pass  through  all  the  stages  of  invisible 
radiation,  but  in  its  most  brilliant  condition  it  embraces, 
in  an  intensified  form,  the  rays  of  all  those  stages. 

And  thus  it  is  with  all  other  kinds  of  matter,  as  far  as 
they  have  hitherto  been  examined.  Coke,  whether  brought 
to  a  white  heat  by  the  electric  current,  or  by  the  oxyhydro- 
gen  jet,  pours  out  invisible  rays  with  augmented  energy,  as 
its  light  is  increased.  The  same  is  true  of  lime,  bricks, 
and  other  substances.  It  is  true  of  all  metals  which  are 
capable  of  being  heated  to  incandescence.  It  also  holds 
good  for  phosphorus  burning  in  oxygen.  Every  gush  of 
dazzling  light  has  associated  with  it  a  gush  of  invisible 
radiant  heat,  which  far  transcends  the  light  in  energy. 
This  condition  of  things  applies  to  all  bodies  capable  of 
being  raised  to  a  white  heat,  either  in  the  solid  or  the  mol- 
ten condition.  It  would  doubtless  also  apply  to  the  lumi- 
nous fogs  formed  by  the  condensation  of  incandescent 
vapors.  In  snch  cases  when  the  curve  representing  the 
radiant  energy  of  the  body  is  constructed,  the  obscure 
radiation  towers  upward  like  a  mountain,  the  luminous 
radiation  resembling  a  mere  "spur"  at  its  base.  From 
the  very  brightness  of  the  light  of  some  of  the  fixed  stars 
we  may  infer  the  intensity  of  that  dark  radiation,  which  is 
the  precursor  and  inseparable  associate  of  their  luminous 
rays. 

We  thus  find  the  luminous  radiation  appearing  when  the 
radiant  body  has  attained  a  certain  temperature;  or,  in 
other  words,  when  the  vibrating  atoms  of  the  body  have 


HADIATION.  41 

attained  a  certain  width  of  swing.  In  solid  and  molten 
bodies  a  certain  amplitude  cannot  be  surpassed  without  the 
introduction  of  periods  of  vibration,  which  provoke  the 
sense  of  vision.  How  are  we  to  figure  this?  If  permitted 
to  speculate,  we  might  ask,  are  not  these  more  rapid  vibra- 
tions the  progeny  of  the  slower?  Is  it  not  really  the  mutual 
action  of  the  atoms,  when  they  swing  through  very  wide 
spaces,  and  thus  encroach  upon  each  other,  that  causes 
them  to  tremble  in  quicker  periods?  If  so,  whatever  be  the 
agency  by  which  the  large  swinging  space  is  obtained,  we 
shall  have  light-giving  vibrations  associated  with  it.  It 
matters  not  whether  the  large  amplitudes  be  produced  by 
the  strokes  of  a  hammer,  or  by  the  blows  of  the  molecules 
of  a  non-luminous  gas,  like  air  at  some  height  above  a  gas- 
flame;  or  by  the  shock  of  the  ether  particles  when  trans- 
mitting radiant  heat.  The  result  in  all  cases  will  be 
incandescence.  Thus,  the  invisible  waves  of  our  filtered 
electric  beam  may  be  regarded  as  generating  synchronous 
vibrations  among  the  atoms  of  the  platinum  on  which  they 
impinge;  but,  once  these  vibrations  have  attained  a  cer- 
tain amplitude,  the  mutual  jostling  of  the  atoms  produces 
quicker  tremors,  and  the  light-giving  waves  follow  as  the 
necessary  product  of  the  heat-giving  ones. 

11.  Absorption   of  Radiant  Heat  by   Vapors   and  Odors. 

We  commenced  the  demonstrations  brought  forward  in 
this  lecture  by  experiments  on  permanent  gases,  and  we 
have  now  to  turn  our  attention  to  the  vapors  of  volatile 
liquids.  Here,  as  in  the  case  of  the  gases,  vast  differences 
have  been  proved  to  exist  between  various  kinds  of  mole- 
cules, as  regards  their  power  of  intercepting  the  calorific 
waves.  While  some  vapors  allow  the  waves  a  comparatively 
free  passage,  the  faintest  mixture  of  other  vapors  causes  a 
deflection  of  the  magnetic  needle.  Assuming  the  absorp- 
tion effected  by  air,  at  a  pressure  of  one  atmosphere,  to  be 
unity,  the  following  are  the  absorptions  effected  by  a  series 
of  vapors  at  a  pressure  of  one-sixtieth  of  an  atmosphere: 

Name  of  vapor.  Absorption. 

Bisulphide  of  carbon 47 

Iodide  of  methyl 115 

Benzol 136 

Amylene 321 

Sulphuric  ether 440 

Formic  ether 648 

Aceticether 613 


42  FRAGMENTS  OF  SCIENCE. 

Bisulphide  of  carbon  is  the  most  transparent  vapor  in 
this  list;  and  acetic  ether  the  most  opaque;  one-sixtieth  of  an 
atmosphere  of  the  former,  however,  produces  47  times  the 
effect  of  a  whole  atmosphere  of  air,  while  one-sixtieth  of  an 
atmosphere  of  the  latter  produces  612  times  the  effect  of  a 
whole  atmosphere  of  air.  Seducing  dry  air  to  the  pressure 
of  the  acetic  ether  here  employed,  and  comparing  them 
then  together,  the  quantity  of  wave-motion  intercepted  by 
the  ether  would  be  many  thousand  times  that  intercepted 
by  the  air. 

Any  one  of  these  vapors  discharged  into  the  free  atmos- 
phere, in  front  of  a  body  emitting  obscure  rays,  intercepts 
more  or  less  of  the  radiation.  A  similar  effect  is  produced 
by  perfumes  diffused  in  the  air,  though  their  attenuation 
is  known  to  be  almost  infinite.  Carrying,  for  example,  a 
current  of  dry  air  over  bibulous  paper,  moistened  by 
patchouli,  the  scent  taken  up  by  the  current  absorbs  30 
times  the  quantity  of  heat  intercepted  by  the  air  which 
carries  it;  and  yet  patchouli  acts  more  feebly  on  radiant 
heat  than  any  other  perfume  yet  examined.  Here  follow 
the  results  obtained  with  various  essential  oils,  the  odor, 
in  each  case,  being  carried  by  a  current  of  dry  air  into  the 
tube  already  employed  for  gases  and  vapors: 

Name  of  perfume.  Absorption. 

Patchouli 30 

Sandal  wood 32 

Geranium 33 

Oil  of  cloves 34 

Attar  of  roses 37 

Bergamot 44 

Neroli 47 

Lavender .'....!...........!.     60 

Lemon 65 

Portugal ...............  J.     67 

Thyme 68 

Kosemary 74 

Oil  of  laurel ' ' '  '     80 

Camomile  flowers 87 

Ca??ia-..- '.'.."".  109 

Spikenard 355 

Amseed 372 

Thus  the  absorption  by  a  tube  full  of  dry  air  being  1, 
that  of  the  odor  of  patchouli  diffused  in  it  is  30,  that  of 
lavender  60,  that  of  rosemary  74,  while  that  of  aniseed 


RADIATION.  43 

amounts  to.  372.     It  would   be  idle   to   speculate  on  the 
quantities  of  matter  concerned  in  these  actions. 

12.  Aqueous  Vapor  in  Relation  to    the    Terrestrial  Tem- 
peratures. 

We  are  now  fully  prepared  for  a  result  which,  without 
such  preparation,  might  appear  incredible.  Water  is,  to 
some  extent,  a  volatile  body,  and  our  atmosphere,  resting 
as  it  does  upon  the  surface  of  the  ocean,  receives  from  it  a 
continual  supply  of  aqueous  vapor.  It  would  be  an  error 
to  confound  clouds  or  fog  or  any  visible  mist  with  the 
vapor  of  water,  which  is  a  perfectly  impalpable  gas,  dif- 
fused, even  on  the  clearest  days,  throughout  the  atmos- 
phere. Compared  with  the  great  body  of  the  air,  the  aque- 
ous vapor  it  contains  is  of  almost  infinitesimal  amount,  99£ 
out  of  every  100  parts  of  the  atmosphere  being  composed 
of  oxygen  and  nitrogen.  In  the  absence  of  experiment, 
we  should  never  think  of  ascribing  to  this  scant  and  varying 
constituent  any  important  influence  on  terrestrial  radia- 
tion; and  yet  its  influence  is  far  more  potent  than  that  of 
the  great  body  of  the  air.  To  say  that  on  a  day  of  average 
humidity  in  England,  the  atmospheric  vapor  exerts  100 
times  the  action  of  the  air  itself,  would  certainly  be  an 
understatement  of  the  fact.  Comparing  a  single  molecule 
of  aqueous  vapor  with  an  atom  of  either  of  the  main  con- 
stituents of  our  atmosphere,  I  am  not  prepared  to  say  how 
many  thousand  times  the  action  of  the  former  exceeds  that 
of  the  latter. 

But  it  must  be  borne  in  mind  that  these  large  numbers 
depend,  in  part,  on  the  extreme  feebleness  of  the  air;  the 
power  of  aqueous  vapor  seems  vast,  because  that  of  the 
air  with  which  it  is  compared  is  infinitesimal.  Abso- 
lutely considered,  however,  this  substance,  notwithstand- 
ing its  small  specific  gravity,  exercises  a  very  potent  action. 
Probably  from  10  to  15  per  cent,  of  the  heat  radiated  from 
the  earth  is  absorbed  within  10  or  20  teet  of  the  earth's 
surface.  This  must  evidently  be  of  the  utmost  consequence 
to  the  life  of  the  world.  Imagine  the  superficial  molecules 
of  the  earth  agitated  with  the  motion  of  heat,  and  impart- 
ing it  to  the  surrounding  ether;  this  motion  would  be  carried 
rapidly  away,  and  lost  forever  to  our  planet,  if  the  waves  of 
ether  had  nothing  but  the  air  to  contend  with  in  their  out- 
ward course.  But  the  aqueous  vapor  takes  up  the  motion, 


44  PR  A  GMEKTS  0V  SCIENCE. 

and  becomes  thereby  heated,  thus  wrapping  the  earth  like 
a  warm  garment,  and  protecting  its  surface  from  the  deadly 
chill  which  it  would  otherwise  sustain.  Various  philoso- 
phers have  speculated  on  the  influence  of  an  atmospheric 
envelope.  De  Saussure,  Fourier,  M.  Pouillet,  and  Mr. 
Hopkins,  have,  one  and  all,  enriched  scientific  literature 
with  contributions  on  this  subject,  but  the  considerations 
which  these  eminent  men  have  applied  to  atmospheric  air, 
have,  if  my  experiments  be  correct,  to  be  transferred  to  the 
aqueous  vapor. 

The  observations  of  meteorologists  furnish  important, 
though  hitherto  unconscious  evidence  of  the  influence  of 
this  agent.  Wherever  the  air  is  dry  we  are  liable  to  daily 
extremes  of  temperature.  By  day,  in  such  places,  the  sun's 
heat  reaches  the  earth  unimpeded,  and  renders  the  maxi- 
mum high;  by  night,  on  the  other  hand,  the  earth's  heat 
escapes  unhindered  into  space,  and  renders  the  minimum 
low.  Hence  the  difference  between  the  maximum  and 
minimum  is  greatest  where  the  air  is  driest.  In  the  plains 
of  India,  on  the  heights  of  the  Himalaya,  in  central  Asia, 
in  Australia — wherever  drought  reigns,  we  have  the  heat  of 
day  forcibly  contrasted  with  the  chill  of  night.  In  the 
Sahara  itself,  when  the  sun's  rays  cease  to  impinge  on  the 
burning  soil,  the  temperature  runs  rapidly  down  to  freez- 
ing, because  there  is  no  vapor  overhead  to  check  the  calo- 
rific drain.  And  here  another  instance  might  be  added  to 
the  numbers  already  known,  in  which  nature  tends,  as  it 
were,  to  check  her  own  excess.  By  nocturnal  refrigeration, 
the  aqueous  vapor  of  the  air  is  condensed  to  water  on  the 
surface  of  the  earth;  and,  as  only  the  superficial  portions 
radiate,  the  act  of  condensation  makes  water  the  radiating 
body.  Now  experiment  proves  that  to  the  rays  emitted  by 
water,  aqueous  vapor  is  especially  opaque.  Hence  the  very 
act  of  condensation,  consequent  on  terrestrial  cooling, 
becomes  a  safeguard  to  the  earth,  imparting  to  its  radia- 
tion that  particular  character  which  renders  it  most  liable 
to  be  prevented  from  escaping  into  space. 

It  might,  however,  be  urged  that,  inasmuch  as  we  derive 
all  our  heat  from  the  sun,  the  selfsame  covering  which 
protects  the  earth  from  chill  must  also  shut  out  the  solar 
radiation.  This  is  partially  true,  but  only  partially;  the 
sun  s  rays  are  different  in  quality  from  the  earth's  rays, 
and  it  does  not  at  all  follow  that  the  substance  which 


RADIATION.  45 

absorbs  the  one  must  necessarily  absorb  the  other.  Through 
a  layer  of  water,  for  example,  one-tenth  of  an  inch  in 
thickness,  the  sun's  rays  are  transmitted  with  comparative 
freedom;  but  through  a  layer  half  this  thickness,  as  Mel- 
loni  has  proved,  no  single  ray  from  the  warmed  earth 
•could  pass.  In  like  manner,  the  sun's  rays  pass  with  com- 
parative freedom  through  the  aqueous  vapor  of  the  air; 
the  absorbing  power  of  this  substance  being  mainly  exerted 
upon  the  invisible  heat  that  endeavors  to  escape  from  the 
earth.  In  consequence  of  this  differential  action  upon 
solar  and  terrestrial  heat,  the  mean  temperature  of  our 
planet  is  higher  than  is  due  to  its  distance  from  the  sun. 

13.  Liquids  and  their  Vapors  in  relation  to  Radiant 
Heat. 

The  deportment  here  assigned  to  atmospheric  vapor  has 
been  established  by  direct  experiments  on  air  taken  from 
the  streets  and  parks  of  London,  from  the  downs  of  Epsom, 
from  the  hills  and  sea-beach  of  the  Isle  of  Wight,  and  also 
by  experiments  on  air  in  the  first  instance  dried,  and  after- 
ward rendered  artificially  humid  by  pure  distilled  water. 
It  has  also  been  established  in  the  following  way:  Ten 
volatile  liquids  were  taken  at  random  and  the  power  of 
these  liquids,  at  a  common  thickness,  to  intercept  the 
waves  of  heat,  was  carefully  determined.  The  vapors  of 
the  liquids  were  next  taken,  in  quantities  proportional  to 
the  quantities  of  liquid,  and  the  power  of  the  vapors  to 
intercept  the  waves  of  heat  was  also  determined.  Com- 
mencing with  the  substance  which  exerted  the  least  absorp- 
tive power,  and  proceeding  onward  to  the  most  energetic, 
the  following  order  of  absorption  was  observed: 

Liquids.  Vapors. 

Bisulphide  of  carbon.  Bisulphide  of  carbon. 

Chloroform.  Chloroform. 

Iodide  of  methyl.  Iodide  of  methyl. 

Iodide  of  ethyl.  Iodide  of  ethyl. 

Benzol.  Benzol. 

Amylene.  Amylene. 

Sulphuric  ether.  Sulphuric  ether. 

Acetic  ether.  Acetic  ether. 

Formic  ether.  Formic  ether. 

Alcohol.  Alcohol. 
Water. 

"\Ve  here  find  the  order  of  absorption  in  both  cashes  to.  t)Q 


46  FRAGMENTS  OF  SCIENCE. 

the  same.  We  have  liberated  the  molecules  from  the 
bonds  which  trammel  them  more  or  less  in  a  liquid  condi- 
tion; but  this  change  in  their  state  of  aggregation  does  not 
change  their  relative  powers  of  absorption.  Nothing  could 
more  clearly  prove  that  the  act  of  absorption  depends 
upon  the  individual  molecule,  which  equally  asserts  its* 
power  in  the  liquid  and  the  gaseous  state.  We  may  safely 
conclude  from  the  above  table  that  the  position  of  a  vapor 
is  determined  by  that  of  its  liquid.  Now  at  the  very  foot 
of  the  list  of  liquids  stands  ivater,  signalizing  itself  above 
all  others  by  its  enormous  power  of  absorption.  And  from 
this  fact,  even  if  no  direct  experiment  on  the  vapor  of 
water  had  ever  been  made,  we  should  be  entitled  to  rank 
that  vapor  as  our  most  powerful  absorber  of  radiant  heat. 
Its  attenuation,  however,  diminishes  its  action.  I  have 
proved  that  a  shell  of  air  fcwo  inches  in  thickness  surround- 
ing our  planet,  and  saturated  with  the  vapor  of  sulphuric 
ether,  would  intercept  35  per  cent,  of  the  earth's  radiation. 
And  though  the  quantity  of  aqueous  vapor  necessary  to 
saturate  air  is  much  less  than  the  amount  of  sulphuric 
ether  vapor  which  it  can  sustain,  it  is  still  extremely  prob- 
able that  the  estimate  already  made  of  the  action  of 
atmospheric  vapor  within  10  feet  of  the  earth's  surface,  is 
under  the  mark;  and  that  we  are  indebted  to  this  wonder- 
ful substance,  to  an  extent  not  accurately  determined,  but 
certainly  far  beyond  what  has  hitherto  been  imagined,  for 
the  temperature  now  existing  at  the  surface  of  the  globe. 

14.  Reciprocity  of  Radiation  and  Absorption. 

Throughout  the  reflections  which  have  hitherto  occupied 
us,  the  image  before  the  mind  has  been  that  of  a  radiant 
source  sending  forth  calorific  waves,  Avhich  on  passing 
among  the  molecules  of  a  gas  or  vapor  were  intercepted  by 
those  molecules  in  various  degrees.  In  all  cases  it  was  the 
transference  of  motion  from  the  ether  to  the  comparatively 
quiescent  molecules  of  the  gas  or  vapor  that  occupied  our 
thoughts.  We  have  now  to  change  the  form  of  our  con- 
ception, and  to  figure  these  molecules  not  as  absorbers  but 
as  radiators,  not  as  the  recipients  but  as  the  originators  of 
wave-motion.  That  is  to  say,  we  must  figure  them  vibrat- 
ing, and  generating  in  the  surrounding  ether  undulations 
which  speed  through  it  with  the  velocity  of  light.  Our 


RADIATION.  47 

object  now  is  to  inquire  whether  the  act  of  chemical  com- 
bi nation,  which  proves  so  potent  as  regards  the  phenomena 
of  absorption,  does  not  also  manifest  its  power  in  the 
phenomena  of  radiation.  For  the  examination  of  this 
question  it  is  necessary,  in  the  first  place,  to  heat  our  gases 
and  vapors  to  the  same  temperature,  and  then  examine 
their  power  of  discharging  the  motion  thus  imparted  to 
them  upon  the  ether  in  which  they  swing. 

A  heated  copper  ball  was  placed  above  a  ring  gas-burner 
possessing  a  great  number  of  small  apertures,  the  burner 
being  connected  by  a  tube  with  vessels  containing  the  vari- 
ous gases  to  be  examined.  By  gentle  pressure  the  gases 
were  forced  through  the  orifices  of  the  burner  against  the 
copper  ball,  where  each  of  them,  being  heated,  rose  in  an 
ascending  column.  A.  thermo-electric  pile,  entirely 
screened  from  the  hot  ball,  was  exposed  to  the  radiation 
of  the  warm  gas,  while  the  deflection  of  a  magnetic  needle 
connected  with  the  pile  declared  the  energy  of  the  radia- 
tion. 

.By  this  mode  of  experiment  it  was  proved  that  the  self- 
same molecular  arrangement  which  renders  a  gas  a  power- 
ful absorber,  renders  it  a  powerful  radiator — that  the  atom 
or  molecule  which  is  competent  to  intercept  the  calorific 
waves  is,  in  the  same  degree,  competent  to  send  them 
forth.  Thus,  while  the  atoms  of  elementary  gases  proved 
themselves  unable  to  emit  any  sensible  amount  of  radiant 
heat,  the  molecules  of  compound  gases  were  shown  to  be 
capable  of  powerfully  disturbing  the  surrounding  ether. 
By  special  modes  of  experiment  the  same  was  proved  to 
hold  good  for  the  vapors  of  volatile  liquids,  the  radiative 
power  of  every  vapor  being  found  proportional  to  its 
absorptive  power. 

The  method  of  experiment  here  pursued,  though  not  of 
the  simplest  character,  is  still  easy  to  grasp.  When  air  is 
permitted  to  rush  into  an  exhausted  tube,  the  temperature 
of  the  air  is  raised  to  a  degree  equivalent  to  the  vis  viva 
extinguished.*  Such  air  is  said  to  be  dynamically  heated, 
and,  if  pure,  it  shows  itself  incompetent  to  radiate,  even 
when  a  rock-salt  window  is  provided  for  the  passage  of  its 
rays.  But  if,  instead  of  being  empty,  the  tube  contain  a 

\  See  page  10  for  a  definition  of  vis  viva, 


48  FRAGMENTS  OF  SCIENCE. 

small  quantity  of  vapor,  the  warmed  air  communicates  its 
heat  by  contact  to  the  vapor,  the  molecules  of  which  con- 
vert into  the  radiant  form  the  heat  imparted  to  them  by 
the  atoms  of  the  air.  By  this  process  also,  which  I  have 
called  Dynamic  Eadiation,  the  reciprocity  of  radiation  and 
absorption  has  been  conclusively  proved.* 

In  the  excellent  researches  of  Leslie,  De  la  Provostaye 
and  Desaius,  and  Balfour  Stewart,  the  same  reciprocity, 
as  regards  solid  bodies,  has  been  variously  illustrated; 
while  the  labors,  theoretical  and  experimental,  of  Kirch- 
hoff  have  given  this  subject  a  wonderful  expansion,  and 
enriched  it  by  applications  of  the  highest  kind.  To  their 
results  are  now  to  be  added  the  foregoing,  whereby  gases 
and  vapors,  which  have  been  hitherto  thought  inaccessible 
to  experiments  with  the  thermo-electric  pile,  are  proved  by 
it  to  exhibit  the  indissoluble  duality  of  radiation  and 
absorption,  the  influence  of  chemical  combination  on  both 
being  exhibited  in  the  most  decisive  and  extraordinary 
way. 

15.  Influence  of  Vibrating  Period  and  Molecular  Form. 
Physical  Analysis  of  the  Human  Breath. 

In  the  foregoing  experiments  with  gases  and  vapors  we 
have  employed  throughout  invisible  rays,  and  found  some 
of  these  bodies  so  impervious  to  radiant  heat,  that  in 
lengths  of  a  few  feet  they  intercept  every  ray  as  effectually 
as  a  layer  of  pitch.  The  substances,  however,  which  show 
themselves  thus  opaque  to  radiant  heat  are  perfectly  trans- 
parent to  light.  Now  the  rays  of  light  differ  from  those 
of  invisible  heat  merely  in  point  of  peliod,  the  former  fail- 
ing to  affect  the  retina  because  their  periods  of  recurrence 
are  too  slow.  Hence,  in  some  way  or  other,  the  trans- 
parency of  our  gases  and  vapors  depends  upon  the  periods 
of  the  waves  which  impinge  upon  them.  What  is  the 
nature  of  this  dependence  ?  The  admirable  researches  of 
Kirchhoff  help  us  to  an  answer.  The  atoms  and  molecules 
of  every  gas  have  certain  definite  rates  of  oscillation,  and 
those  waves  of  ether  are  most  copiously  absorbed  whose 

*  When  heated  air  imparts  its  motion  to  another  gas  or  vapor,  the 
transference  of  heat  is  accompanied  by  a  change  of  vibrating  period. 
The  Dynamic  Radiation  of  vapors  is  rendered  possible  by  this  tra,ns- 
wutation.  of  vibrations, 


CAPTATION.  49 

periods  of  recurrence  synchronize  with  those  of  the  atomic 
groups  among  which  they  pass.  Thus,  when  we  find  the 
invisible  rays  absorbed  and  the  visible  ones  transmitted  by 
a  layer  of  gas,  we  conclude  that  the  oscillating  periods  of 
the  atoms  constituting  the  gaseous  molecules  coincide  with 
those  of  the  invisible,  and  not  with  those  of  the  visible 
spectrum. 

It  requires  some  discipline  of  the  imagination  to  form  a 
clear  picture  of  this  process.  Such  a  picture  is,  however, 
possible,  and  ought  to  be  obtained.  When  the  waves  of 
ether  impinge  upon  molecules  whose  periods  of  vibration 
coincide  with  the  recurrence  of  the  undulations,  the  timed 
strokes  of  the  waves  augment  the  vibration  of  the  mole- 
cules, as  a  heavy  pendulum  is  set  in  motion  by  well-timed 
puffs  of  breath.  Millions  of  millions  of  shocks  are  received 
every  second  from  the  calorific  waves;  and  it  is  not  difficult 
to  see  that  as  every  wave  arrives  just  in  time  to  repeat  the 
action  of  its  predecessor,  the  molecules  must  finally  be 
caused  to  swing  through  wider  spaces  than  if  the  arrivals 
were  not  so  timed.  In  fact,  it  is  not  difficult  to  see  that  an 
assemblage  of  molecules,  operated  upon  by  contending 
waves,  might  remain  practically  quiescent.  This  is  actually 
the  case  when  the  waves  of  the  visible  spectrum  pass 
through  a  transparent  gas  or  vapor.  There  is  here  no 
sensible  transference  of  motion  from  the  ether  to  the  mole- 
cules; in  other  words/ there  is  no  sensible  absorption  of 
heat. 

One  striking  example  of  the  influence  of  period  may  be 
here  recorded.  Carbonic  acid  gas  is  one  of  the  feeblest 
absorbers  of  the  radiant  heat  emitted  by  solid  bodies.  It 
is,  for  example,  to  a  great  extent  transparent  to  the  rays 
emitted  by  the  heated  copper  plate  already  referred  to. 
There  are,  however,  certain  rays,  comparatively  few  in 
number,  emitted  by  the  copper,  to  which  the  carbonic  acid 
is  impervious;  and  could  we  obtain  a  source  of  heat  emit- 
ting such  rays  only,  we  should  find  carbonic  acid  more 
opaque  to  the  radiation  from  that  source  than  any  other 
gas.  Such  a  source  is  actually  found  in  the  flame  of  car- 
bonic oxide,  where  hot  carbonic  acid  constitutes  the  main 
radiating  body.  Of  the  rays  emitted  by  our  heated  plate 
of  copper,  olefiant  gas  absorbs  ten  times  the  quantity 
absorbed  by  carbonic  acid.  Of  the  rays  emitted  by  a  car- 
bonic oxide  flame,  carbonic  acid  absorbs  twice  as  much  as 


50  FRA  GMENTS  OF  SCIENCE. 

olefiant  gas.  This  wonderful  change  in  the  power  of  the 
former,  as  an  absorber,  is  simply  due  to  the  fact  that  the 
periods  of  the  hot  and  cold  carbonic  acid  are  identical,  and 
that  the  waves  from  the  flame  freely  transfer  their  motion 
to  the  molecules  which  synchronize  with  them.  Thus  it  is 
that  the  tenth  of  an  atmosphere  of  carbonic  acid,  enclosed 
in  a  tube  four  feet  long,  absorbs  60  per  cent,  of  the  radia- 
tion from  a  carbonic  oxide  flame,  while  one-thirtieth  of  an 
atmosphere  absorbs  48  per  cent,  of  the  heat  from  the  same 
sou  rce. 

In  fact,  the  presence  of  the  minutest  quantity  of  car- 
bonic acid  may  be  detected  by  its  action  on  the  rays  from 
the  carbonic  oxide  flame.  Carrying,  for  example,  the  dried 
human  breath  into  a  tube  four  feet  long,  the  absorption 
ffhere  effected  by  the  carbonic  acid  of  the  breath  amounts 
to  50  per  cent,  of  the  entire  radiation.  Radiant  heat  may 
indeed  be  employed  us  a  means  of  determining  practically 
the  amount  of  carbonic  acid  expired  from  the  lungs.  My 
late  assistant,  Mr.  Barrett,  while  under  my  direction, 
made  this  determination.  The  absorption  produced  by 
the  breath  freed  from  its  moisture,  but  retaining  its  car- 
bonic acid,  was  first  determined.  Carbonic  acid,  artificially 
prepared,  was  then  mixed  with  dry  air  in  such  proportions 
that  the  action  of  the  mixture  upon  the  rays  of  heat  was 
the  same  as  that  of  the  dried  breath.  The  percentage  of 
the  former  being  known,  immediately  gave  that  of  the 
latter.  The  same  breath,  analyzed  chemically  by  Dr. 
Frankland,  and  physically  by  Mr.  Barrett,  gave  the  follow- 
ing results: 

Percentage  of  Carbonic  Acid  in  the  Human  Breatli. 
Chemical  analysis  Physical  analysis 

4.66 4.56 

5.33 5.22 

Jt  is  thus  proved  that  in  the  quantity  of  ethereal  motion 
which  it  is  competent  to  take  up,  we  have  a  practical 
measure  of  the  carbonic  acid  of  the  breath,  and  hence  of 
the  combustion  going  on  in  the  human  lungs. 

Still  this  question  of  period,  though  of  the  utmost  im- 
portance, is  not  competent  to  account  for  the  whole  of  the 
observed  facts.  The  ether,  as  far  as  we  know,  accepts 
vibrations  of  all  periods  with  the  same  readiness.  To  it 
the  oscillations  of  an  atom  of  free  oxygen  are  just  as 


RADIATION.  51 

acceptable  as  those  of  the  atoms  in  a  molecule  of  olefiant 
gas;  that  the  vibrating  oxygen  then  stands  so  far  below  the 
olefiant  gas  in  radiant  power  must  be  referred  not  to 
period,  but  to  some  other  peculiarity.  The  atomic  group 
which  constitutes  the  molecule  of  olefiant  gas,  produces 
many  thousand  times  the  disturbance  caused  by  the  oxygen, 
it  may  be,  because  the  group  is  able  to  lay  a  vastly  more 
powerful  hold  upon  the  ether  than  the  single  atoms  can. 
Another  and  probably  very  potent  cause  of  the  difference 
may  be  that  the  vibrations,  oeing  those  of  the  constituent 
atoms  of  the  molecule,*  are  generated  in  highly  condensed 
ether,  which  acts  like  condensed  air  upon  sound.  But 
whatever  may  be  the  fate  of  these  attempts  to  visualize  the 
physics  of  the  process,  it  will  still  remain  true,  that  to 
account  for  the  phenomena  of  radiation  and  absorption  we 
must  take  into  consideration  the  shape,  size,  and  condi- 
tion of  the  ether  within  the  molecules,  by  which  the  ex- 
ternal ether  is  disturbed. 

16.  Summary  and  Conclusion. 

Let  us  now  cast  a  momentary  glance  over  the  ground 
that  we  have  left  behind.  The  general  nature  of  lignt  and 
heat  was  first  briefly  described:  the  compounding  of  matter 
from  elementary  atoms,  and  the  influence  of  the  act  of 
combination  on  radiation  and  absorption,  were  considered 
and  experimentally  illustrated.  Through  the  transparent 
elementary  gases  radiant  heat  was  found  to  pass  as  through 
a  vacuum,  while  many  of  the  compound  gases  presented 
almost  impassable  obstacles  to  the  calorific  waves.  This 
deportment  of  the  simple  gases  directed  our  attention  to 
other  elementary  bodies,  the  examination  of  which  led  to 
the  discovery  that  the  element  iodine,  dissolved  in  bisul- 
phide of  carbon,  possesses  the  power  of  detaching,  with 
extraordinary  sh.arpness,  the  light  of  the  spectrum  from  its 
heat,  intercepting  all  luminous  rays  up  to  the  extreme  red, 
and  permitting  the  calorific  rays  beyond  the  red  to  puss 
freely  through  it.  This  substance  was  then  employed  to 
filter  the  beams  of  the  electric  light,  and  to  form  foci  of 
invisible  rays  so  intense  as  to  produce  almost  all  the  effects 
obtainable  in  an  ordinary  fire.  Combustible  bodies  were 

*  See  "  Physical   Considerations,"  Art.  iv.,  p.  102. 


52  FRAGMENTS  OF  SCIENCE. 

burned,  and  refractory  ones  were  raised  to  a  white  heat,  by 
the  concentrated  invisible  rays.  Thus,  by  exalting  their 
refrangibility,  the  invisible  rays  of  the  electric  light  were 
rendered  visible,  and  all  the  colors  of  the  solar  spectrum 
were  extracted  from  utter  darkness.  The  extreme  rich- 
ness of  the  electric  light  in  invisible  rays  of  low  refrangi- 
bility was  demonstrated,  one-eighth  only  of  its  radiation 
consisting  of  luminous  rays.  The  dead  ness  of  the  optic 
nerve  to  those  invisible  rays  was  proved,  and  experiments 
were  then  added  to  show  that  the  bright  and  the  dark  rays 
of  a  solid  body,  raised  gradually  to  incandescence,  are 
strengthened  together;  intense  dark  heat  being  an  invari- 
ble  accompaniment  of  intense  white  heat.  A  sun  could 
not  be  formed,  or  a  meteorite  rendered  luminous,  on  any 
other  condition.  The  light-giving  rays  constituting  only 
a  small  fraction  of  the  total  radiation,  their  unspeakable 
importance  to  us  is  due  to  the  fact  that  their  periods  are 
attuned  to  the  special  requirements  of  the  eye. 

Among  the  vapors  of  volatile  liquids  vast  differences 
were  also  found  to  exist,  as  regards  their  powers  of  absorp- 
tion. We  followed  various  molecules  from  a  state  of 
liquid  to  a  state  of  gas,  and  found,  in  both  states  of  aggre- 
gation, the  power  of  the  individual  molecules  equally 
asserted.  The  position  of  a  vapor  as  an  absorber  of 
radiant  heat  was  shown  to  be  determined  by  that  of  the 
liquid  from  which  it  is  derived.  Eeversing  our  conceptions, 
and  regarding  the  molecules  of  gases  and  vapors  not  as  the 
recipients  but  as  the  originators  of  wave-motion;  not  as 
absorbers  but  as  radiators;  it  was  proved  that  the  powers 
of  absorption  and  radiation  went  hand  in  hand,  the  self- 
same chemical  act  which  rendered  a  body  competent  to 
intercept  the  waves  of  ether  rendering  it  competent,  in  the 
same  degree,  to  generate  them.  Perfumes  were  next  sub- 
jected to  examination,  and,  notwithstanding  their  extra- 
ordinary tenuity,  they  were  found  vastly  superior,  in  point 
of  absorptive  power,  to  the  body  of  the  air  in  which  they 
were  diffused.  We  were  led  thus  slowly  up  to  the  exami- 
nation of  the  most  widely  diffused  and  most  important  of 
all  vapors — the  aqueous  vapor  of  our  atmosphere,  and  we 
found  in  it  a  potent  absorber  of  the  purely  calorific  rays. 
The  power  of  this  substance  to  influence  climate,  and  its 
general  influence  on  the  temperature  of  the  earth,  were 


RADIATION.  53 

then  briefly  dwelt  upon.  A  cobweb  spread  above  a  blos- 
som is  sufficient  to  protect  it  from  nightly  chill;  and  thus 
the  aqueous  vapor  of  our  air,  attenuated  as  it  is,  checks 
the  drain  of  terrestrial  heat,  and  saves  the  surface  of  our 
planet  from  the  refrigeration  which  would  assuredly  accrue, 
were  no  such  substance  interposed  between  it  and  the 
voids  of  space.  We  considered  the  influence  of  vibrating 
period,  and  molecular  form,  on  absorption  and  radiation, 
and  finally  deduced,  from  its  action  upon  radiant  heat, 
the  exact  amount  of  carbonic  acid  expired  by  the  human 
lungs. 

Thus,  in  brief  outline,  were  placed  before  you  some  of 
the  results  of  recent  inquiries  in  the  domain  of  radiation, 
and  my  aim  throughout  hys  been  to  raise  in  your  minds 
distinct  physical  images  of  the  various  processes  involved 
in  our  researches.  It  is  thought  by  some  that  natural 
science  has  a  deadening  influence  on  the  imagination,  and 
a  doubt  might  fairly  be  raised  as  to  the  value  of  any  study 
which  would  necessarily  have  this  effect.  But  the  experi- 
ence of  the  last  hour  must,  I  think,  have  convinced  you, 
that  the  study  of  natural  science  goes  hand  in  hand  with 
the  culture  of  the  imagination.  Throughout  the  greater 
part  of  this  discourse  we  have  been  sustained  by  this 
faculty.  We  have  been  picturing  atoms,  and  molecules, 
and  vibrations,  and  waves,  which  eye  has  never  seen  nor 
ear  heard,  and  which  can  only  be  discerned  by  the  exercise 
of  imagination.  This,  in  fact,  is  the  faculty  which  en- 
ables us  to  transcend  the  boundaries  of  sense,  and  connect 
the  phenomena  of  our  visible  world  with  those  of  an  invis- 
ible one.  Without  imagination  we  never  could  have  risen 
to  the  conceptions  which  have  occupied  us  here  to-day;  and 
in  proportion  to  vour  power  of  exercising  this  faculty 
aright,  and  of  associating  definite  mental  images  with  the 
terms  employed,  will  be  the  pleasure  and  the  profit  which 
you  will  derive  from  this  lecture.  The  outward  facts  of 
nature  are  insufficient  to  satisfy  the  mind.  We  cannot  be 
content  with  knowing  that  the  light  and  heat  of  the  sun 
illuminate  and  warm  the  world.  We  are  led  irresistibly  to 
inquire,  •'  What  is  light,  and  what  is  heat?"  and  this  ques- 
tion leads  us  at  once  out  of  the  region  of  sense  into  that  of 
imagination.* 

•This  line  of  thought  was  pursued  further  five  years  subse-, 
quently,  gee  "  Scientific  Use  of  fhe  Imagination  ". 


54  FMA  GMENTS  OF  SCIENCE. 

Thus  pondering,  and  questioning,  and  striving  to  sup- 
plement that  which  is  felt  and  seen,  but  which  is  incom- 
plete, by  something  unfelt  and  unseen  which  is  necessary 
to  its  completeness,  men  of  genius  have  in  part  discerned, 
not  only  the  nature  of  light  and  heat,  but  also,  through 
them,  the  general  relationship  of  natural  phenomena. 
The  working  power  of  Nature  consists  of  actual  or  poten- 
tial motion,  of  which  all  its  phenomena  are  but  special 
forms.  This  motion  manifests  itself  in  tangible  and  in 
intangible  matter,  being  incessantly  transferred  from  the 
one  to  the  other,  and  incessantly  transformed  by  the 
change.  It  is  as  real  in  the  waves  of  the  ether  as  in  the 
waves  of  the  sea;  the  latter — derived  as  they  are  from 
winds,  which  in  their  turn  are  derived  from  the  sun — are, 
indeed,  nothing  more  than  the  heaped-up  motion  of  the 
ether  waves.  It  is  the  calorific  waves  emitted  by  the  sun 
which  heat  our  air,  produce  our  winds,  and  hence  agitate 
our  ocean.  And  whether  they  break  in  foam  upon  the 
shore,  or  rub  silently  against  the  ocean's  bed,  or  subside 
by  the  mutual  friction  of  their  own  parts,  the  sea  waves, 
which  cannot  subside  without  producing  heat,  finally 
resolve  themselves  into  waves  of  ether,  thus  regenerating 
the  motion  from  which  their  temporary  existence  was 
derived.  This  connection  is  typical.  Nature  is  not  an 
aggregate  of  independent  parts,  but  an  organic  whole.  If 
you  open  a  piano  and  sing  into  it,  a  certain  string  will  re- 
spond. Change  the  pitch  of  your  voice;  the  first  string 
ceases  to  vibrate,  but  another  replies.  Change  again  the 
pitch;  the  first  two  strings  are  silent,  while  another  re- 
sounds. Thus  is  sentient  man  acted  on  by  Nature,  the 
optic,  the  auditory  and  other  nerves  of  the  human  body 
being  so  many  strings  differently  tuned,  and  responsive  to 
different  forms  of  the  universal  power. 


CHAPTER  III. 

ON    RADIANT    HEAT    IK    RELATION    TO    THE    COLOR   AND 
CHEMICAL   CONSTITUTION    OF    BODIES.* 

ONE  OF  the  most  important  functions  of  physical  science, 
considered  as  a  discipline  of  the  mind,  is  to  enable  us  by 
means  of  the  sensible  processes  of  Nature  to  apprehend  the 

*  A  discourse  delivered  in  the  lioval  Institution  of  Great  Britain, 
Jan.  19,  1866. 


ON  RADIANT  HEAT:  55 

insensible.  The  sensible  processes  give  direction  to  the 
line  of  thought;  but  this  once  given,  the  length  of  the 
line  is  not  limited  by  the  boundaries  of  the  senses.  Indeed, 
the  domain  of  the  senses,  in  Nature,  is  almost  infinitely 
small  in  comparison  with  the  vast  region  accessible  to 
thought  which  lies  beyond  them.  From  a  few  observations 
of  a  comet,  when  it  comes  within  the  range  of  his  telescope, 
an  astronomer  can  calculate  its  path  in  regions  which  no 
telescope  can  reach:  and  in  like  manner,  by  means  of  data 
furnished  in  the  narrow  world  of  the  senses,  we  make  our- 
selves at  home  in  other  and  wider  worlds,  which  are  trav- 
ersed by  the  intellect  alone. 

From  the  earliest  ages  the  questions,  "  What  is  light  ?" 
and  "  What  is  heat?"  have  occurred  to  the  minds  of  men; 
but  these  questions  never  would  have  been  answered  had 
they  not  been  preceded  by  the  question,  "  What  is  sound?  " 
Amid  the  grosser  phenomena  of  acoustics  the  mind  was 
first  disciplined,  conceptions  being  thus  obtained  from 
direct  observation,  which  were  afterward  applied  to  phe- 
nomena of  a  character  far  too  subtle  to  be  observed 
directly.  Sound  we  know  to  be  clue  to  vibratory  motion. 
A  vibrating  tuning-fork,  for  example,  molds  the  air 
around  it  into  undulations  or  waves,  which  speed  away  on 
all  sides  with  a  certain  measured  velocity,  impinge  upon 
the  drum  of  the  ear,  shake  the  auditory  nerve;  and  awake 
in  the  brain  the  sensation  of  sound.  When  sufficiently 
near  a  sounding  body  we  can  feel  the  vibrations  of  the  air. 
A  deaf  man,  for  example,  plunging  his  hand  into  a  bell 
when  it  is  sounded,  feels  through  the  common  nerves  of 
his  body  those  tremors  which,  when  imparted  to  the  nerves 
of  healthy  ears,  are  translated  into  sound.  There  are  various 
wavs  of  rendering  those  sonorous  vibrations  notoniy  tangible 
but  visible;  and  it  was  not  until  numberless  experiments 
of  this  kind  had  been  executed  that  the  scientific  investi- 
gator abandoned  himself  wholly,  and  without  a  shadow  of 
misgiving,  to  the  conviction  that  what  is  sound  within  us 
is,  outside  of  us,  a  motion  of  the  air. 

But  once  having  established  this  fact — once  having 
proved  beyond  all  doubt  that  the  sensation  of  sound  is  pro- 
duced by  an  agitation  of  the  auditory  nerve — the  thought 
soon  suggested  itself  that  light  might  be  due  to  an  agitation 
of  the  optic  nerve.  This  was  a  great  step  in  advance  of 
that  ancient  notion  which  regarded  light  as  something 


56  FRAGMENTS  OF  SCIENCE. 

emitted  by  the  eye,  and  not  as  anything  imparted  to  it. 
But  if  light  be  produced  byan  agitation  of  the  retina,  what 
is  it  that  produces  the  agitation?  Newton,  you  know, 
supposed  minute  particles  to  be  shot  through  the  humors 
of  the  eye  against  the  retina,  which  he  supposed  to  hang 
like  a  target  at  the  back  of  the  eye.  The  impact  of  these 
particles  against  the  target,  Newton  believed  to  be  the 
cause  of  light.  But  Newton's  notion  has  not  held  its 
ground,  being  entirely  driven  from  the  field  by  the  more 
wonderful  and  far  more  philosophical  notion  that  light, 
like  sound,  is  a  product  of  wave-motion. 

The  domain  in  which  this  motion  of  light  is  carried  on 
lies  entirely  beyond  the  reach  of  our  senses.  The  waves  of 
light  require  a  medium  for  their  formation  and  propaga- 
tion; but  we  cannot  see,  or  feel,  or  taste,  or  smell  this 
medium.  How,  then,  has  its  existence  been  established? 
By  showing,  that  by  the  assumption  of  this  wonderful  in- 
tangible ether,  all  the  phenomena  of  optics  are  accounted 
for,  with  fullness,  and  clearness,  and  conclusiveuess,  which 
leave  no  desire  of  the  intellect  unsatisfied.  When  the  law 
of  gravitation  first  suggested  itself  to  the  mind  of  Newton, 
what  did  he  do?  He  set  himself  to  examine  whether  it 
accounted  for  all  the  facts.  He  determined  the  courses  of 
the  planets;  he  calculated  the  rapidity  of  the  moon's  fall 
toward  the*  earth;  he  considered  the  precession  of  the 
equinoxes,  the  ebb  and  flow  of  the  tides,  and  found  all  ex- 
plained by  the  law  of  gravitation.  He  therefore  regarded 
this  law  as  established,  and  the  verdict  of  science  subse- 
quently confirmed  his  conclusion.  On  similar,  and,  if 
possible,  on  stronger  grounds,  we  found  our  belief  in  the 
existence  of  the  universal  ether.  It  explains  facts  far 
more  various  and  complicated  than  those  on  which  Newton 
based  his  law.  If  a  single  phenomenon  could  be  pointed 
out  which  the  ether  is  proved  incompetent  to  explain,  we 
should  have  to  give  it  up;  but  no  such  phenomenon  has 
ever  been  pointed  out.  It  is,  therefore,  at  least  as  certain 
that  space  is  filled  with  a  medium,  by  means  of  which  suns 
and  stars  diffuse  their  radiant  power,  as  that  it  is  traversed 
by  that  force  which  holds  in  its  grasp,  not  only  our  planet- 
arv  system,  but  the  immeasurable  heavens  themselves. 

There  is  no  more  wonderful  instance  than  this  of  the 
production  of  a  line  of  thought,  from  the  world  of  the 
.senses  into  the  region  of  pure  imagination.  I  mean  by 


ON  RADIANT  HEAT.  57 

imagination  here,  not  that  play  of  fancy  which  can  give 
to  airy  nothings  a  local  habitation  and  a  name,  but  that 
power  which  enables  the  mind  to  conceive  realities  which 
lie  beyond  the  range  of  the  senses — to  present  to  itself 
distinct  images  of  processes  which,  though  mighty  in  the 
aggregate  beyond  all  conception,  are  so  minute  individually 
as  to  elude  all  observation.  It  is  the  waves  of  air  excited 
by  a  tuning-fork  which  render  its  vibrations  audible.  It 
is  the  waves  of  ether  sent  forth  from  those  lamps  overhead 
which  render  them  luminous  to  us;  but  so  minute  are 
these  waves,  that  it  would  take  from  30,000  to  60,000  of 
them  placed  end  to  end  to  cover  a  single  inch.  Their 
number,  however,  compensates  for  their  minuteness.  Tril- 
lions of  them  have  entered  your  eyes,  and  hit  the  retina  at 
the  backs  of  your  eyes,  in  the  time  consumed  in  the  utter- 
ance of  the  shortest  sentence  of  this  discourse.  This  is 
the  steadfast  result  of  modern  research;  but  we  never 
could  have  reached  it  without  previous  discipline.  We 
never  could  have  measured  the  waves  of  light,  nor  even 
imagined  them  to  exist,  had  we  not  previously  exercised 
ourselves  among  the  waves  of  sound.  Sound  and  light  are 
now  mutually  helpful,  the  conceptions  of  each  being  ex- 
panded, strengthened,  and  defined  by  the  conceptions  of 
the  other. 

The  ether  which  conveys  the  pulses  of  light  and  heat 
not  only  fills  celestial  space,  swathing  suns,  and  planets, 
and  moons,  but  it  also  encircles  the  atoms  of  which  these 
bodies  are  composed.  It  is  the  motion  of  these  atoms,  and 
not  that  of  any  sensible  parts  of  bodies,  that  the  ether  con- 
veys. This  motion  is  the  objective  cause  of  what,  in  our 
sensations,  are  light  and  heat.  An  atom,  then,  sending 
its  pulses  through  the  ether,  resembles  a  tuning-fork 
sending  its  pulses  through  the  air.  Let  us  look  for  a 
moment  at  this  thrilling  medium,  and  briefly  consider  its 
relation  to  the  bodies  whose  vibrations  it  conveys.  Dif- 
ferent bodies,  when  heated  to  the  same  temperature,  pos- 
sess very  different  powers  of  agitating  the  ether:  some 
are  good  radiators,  others  are  bad  radiators:  which  means 
that  some  are  so  constituted  as  to  communicate  their 
atomic  motion  freely  to  the  ether,  producing  therein  pow- 
erful undulations;  while  the  atoms  of  others  are  unable 
thus  to  communicate  their  motions,  but  glide  through 
the  medium  without  materially  disturbing  its  repose, 


58  FRAGMENTS  OF  SCIENCE. 

Kecent  experiments  have  proved  that  elementary  bodies, 
except  under  certain  anomalous  conditions,  belong  to  the 
class  of  bad  radiators.  An  atom,  vibrating  in  the  ether, 
resembles  a  naked  tuning-fork  vibrating  in  the  air.  The 
amount  of  motion  communicated  to  the  air  by  the  thin 
prongs  is  too  small  to  evoke  at  any  distance  the  sensation 
of  sound.  But  if  we  permit  the  atoms  to  combine  chem- 
ically and  form  molecules,  the  result,  in  many  cases,  is  an 
enormous  change  in  the  power  of  radiation.  The  amount 
of  ethereal  disturbance,  produced  by  the  combined  atoms 
of  a  boSy,  may  be  many  thousand  times  that  produced  by 
the  same  atoms  when  uncombined. 

The  pitch  of  a  musical  note  depends  upon  the  rapidity 
of  its  vibrations,  or,  in  other  words,  on  the  length  of  its 
waves.  Now,  the  pitch  of  a  note  answers  to  the  color  of 
light.  Taking  a  slice  of  white  light  from  the  sun,  or  from 
an  electric  lamp,  and  causing  the  light  to  pass  through  an 
arrangement  of  prisms,  it  is  decomposed.  We  have  the 
effect  obtained  by  Newton,  who  first  unrolled  the  solar 
beam  into  the  splendors  of  the  solar  spectrum.  At  one 
end  of  this  spectrum  we  have  red  light,  at  the  other,  vio- 
let; and  between  those  extremes  lie  the  other  prismatic 
colors.  As  we  advance  along  the  spectrum  from  the  red 
to  the  violet,  the  pitcli  of  the  light — if  I  may  use  the  ex- 
pression— heightens,  the  sensation  of  violet  being  pro- 
duced by  a  more  rapid  succession  of  impulses  than  that 
which  produces  the  impression  of  red.  The  vibrations  of 
the  violet  are  about  twice  as  rapid  as  those  of  the  red;  in 
other  words,  the  range  of  the  visible  spectrum  is  about  an 
octave. 

There  is  no  solution  of  continuity  in  this  spectrum; 
one  color  changes  into  another  by  insensible  gradations. 
It  is  as  if  an  infinite  number  of  tuning-forks,  of  gradually 
augmenting  pitch,  were  vibrating  at  the  same  time.  But 
turning  to  another  spectrum — that,  namely,  obtained  from 
the  incandescent  vapor  of  silver — you  observe  that  it  con- 
sists of  two  narrow  and  intensely  luminous  green  bands. 
Here  it  is  as  if  two  forks  only,  of  slightly  different  pitch, 
were  vibrating.  The  length  of  the  waves  which  produce 
this  first  band  is  such  that  47,460  of  them,  placed  end  to 
end,  would  fill  an  inch.  The  waves  which  produce  the 
second  band  are  a  little  shorter;  it  would .  take  of  these 
47,930  to  fill  an  inch.  In  the  case  of  the  first  baud,  the 


ON  RADIANT  HE  A  T.  59 

number  of  impulses  imparted,  in  one  second,  to  every  eye 
which  sees  it,  is  577  millions  of  millions;  while  the  num- 
ber of  impulses  imparted,  in  the  same  time,  by  the  second 
band  is  000  millions  of  millions.  We  may  project  upon  a 
white  screen  the  beautiful  stream  of  green  light  from 
which  these  bands  were  derived.  This  luminous  stream  is 
the  incandescent  vapor  of  silver.  The  rates  of  vibration  of 
the  atoms  of  that  vapor  are  as  rigidly  fixed  as  those  of  two 
tuning-forks;  and  to  whatever  height  the  temperature  of 
the  vapor  may  be  raised,  the  rapidity  of  its  vibrations,  and 
consequently  its  color,  which  wholly  depends  upon  that 
rapidity,  remain  unchanged. 

The  vapor  of  water,  as  well  as  the  vapor  of  silver,  has  its 
definite  periods  of  vibration,  and  these  are  such  as  to  dis- 
qualify the  vapor,  when  acting  freely  as  such,  from  being 
raised  to  a  white  heat.  The  oxyhydrogen  flame,  for 
example,  consists  of  hot  aqueous  vapor.  It  is  scarcely 
visible  in  the  air  of  this  room,  and  it  would  be  still  less 
visible  if  we  could  burn  the  gas  in  a  clean  atmosphere. 
But  the  atmosphere,  even  at  the  summit  of  Mont  Blanc,  is 
dirty;  in  London  it  is  more  than  dirty;  and  the  burning 
dirt  gives  to  this  flame  the  greater  portion  of  its  present 
light.  But  the  heat  of  the  flame  is  enormous.  Cast  iron 
fuses  at  a  temperature  of  2,000°  Fahr.;  while  the  temper- 
ature of  the  oxyhydrogen  flame  is  6,000°  Fahr.  A  piece 
of  platinum  is  heated  to  vivid  redness,  at  a  distance  of  two 
inches  beyond  the  visible  termination  of  the  flame.  The 
vapor  which  produces  incandescence  is  here  absolutely 
dark.  In  the  flame  itself  the  platinum  is  raised  to  daz- 
zling whiteness,  and  is  even  pierced  by  the  flame.  When 
this  flame  impinges  on  a  piece  of  lime,  we  have  the  daz- 
zling Drummond  light.  But  the  light  is  here  due  to  the 
fact  that  when  it  impinges  upon  the  solid  body,  the  vibra- 
tions excited  in  that  body  by  the  flame  are  of  periods  dif- 
ferent from  its  own. 

Thus  far  we  have  fixed  our  attention  on  atoms  and 
molecules  in  a  state  of  vibration,  and  surrounded  by  a 
medium  which  accepts  their  vibrations,  and  transmits 
them  through  space.  But  suppose  the  waves  generated  by 
one  system  of  molecules  to  impinge  upon  another  system, 
how  will  the  waves  be  affected?  Will  they  be  stopped,  or 
will  they  be  permitted  to  pass?  Will  they  transfer  their 
motion  to  the  molecules  on  which  they  impinge,  or  will 


60  FRAGMENTS  OF  SCIENCE. 

they  glide  round  the  molecules,  through  the  intermolecu- 
lar  spaces,  and  thus  escape? 

The  answer  to  this  question  depends  upon  a  condition 
which  may  be  beautifully  exemplified  by  an  experiment  on 
sound.  These  two  tuning-forks  are  tuned  absolutely  alike. 
They  vibrate  with  the  same  rapidity,  and,  mounted  thus 
upon  their  resonant  cases,  you  hear  them  loudly  sounding  the 
same  musical  note.  Stopping  one  of  the  forks,  I  throw 
the  other  into  strong  vibration,  and  bring  that  other  near 
the  silent  fork,  but  not  into  contact  with  it.  Allowing 
them  to  continue  in  this  position  for  four  or  five  seconds, 
and  then  stopping  the  vibrating  fork,  the  sound  does  not 
cease.  The  second  fork  has  taken  up  the  vibrations  of  its 
neighbor,  and  is  now  sounding  in  its  turn.  Dismounting 
one  of  the  forks,  and  permitting  the  other  to  remain  upon 
its  stand,  I  throw  the  dismounted  fork  into  strong  vibra- 
tion. You  cannot  hear  it  sound.  Detached  from  its  case, 
the  amount  of  motion  which  it  can  communicate  to  the 
air  is  too  small  to  be  sensible  at  any  distance.  When  the 
dismounted  fork  is  brought  close  to  the  mounted  one,  but 
not  into  actual  contact  with  it,  out  of  the  silence  rises  a 
mellow  sound.  Whence  comes  it?  From  the  vibrations 
which  have  been  transferred  from  the  dismounted  fork  to 
the  mounted  one. 

That  the  motion  should  thus  transfer  itself  through  the 
air  it  is  necessary  that  the  two  forks  should  be  in  perfect 
unison.  If  a  morsel  of  wax  not  larger  than  a  pea  be  placed 
on  one  of  the  forks,  it  is  rendered  thereby  powerless  to 
affect,  or  to  be  affected  by  the  other.  It  is  easy  to  under- 
stand this  experiment.  The  pulses  of  the  one  fork  can 
affect  the  other,  because  they  are  perfectly  timed.  A  single 
pulse  causes  the  prong  of  the  silent  fork  to  vibrate  through 
an  infinitesimal  space.  But  just  as  it  has  completed  this 
small  vibration,  another  pulse  is  ready  to  strike  it.  Thus, 
the  impulses  add  themselves  together.  In  the  five  seconds 
during  which  the  forks  were  held  near  each  other,  the 
vibrating  fork  sent  1,280  waves  against  its  neighbor  and 
those  1,280  shocks,  all  delivered  at  the  proper  moment,  all, 
as  I  have  said,  perfectly  timed,  have  given  such  strength 
to  the  vibrations  of  the  mounted  fork  as  to  render  them 
audible  to  all. 

Another  curious  illustration  of  the  influence  of  syn- 
chronism on  musical  vibrations,  is  this;  Three  small  gas- 


ON  RADIANT  HE  A  T.  61 

flames  are  inserted  into  three  glass  tubes  of  different 
lengths.  Each  of  these  flames  can  be  caused  to  emit  a 
musical  note,  the  pitch  of  which  is  determined  by  the 
length  of  the  tube  surrounding  the  flame.  The  shorter 
the  tube  the  higher  is  the  pitch.  The  flames  are  now 
silent  within  their  respective  tubes,  but  each  of  them  can 
be  caused  to  respond  to  a  proper  note  sounded  anywhere 
in  this  room.  With  an  instrument  called  a  syren,  a  pow- 
erful musical  note,  of  gradually  increasing  pitch,  can  be 
produced.  Beginning  with  a  low  note,  anti  ascending 
gradually  to  a  higher  one,  we  finally  attain  the  pitch  of 
the  flame  in  the  longest  tube.  The  moment  it  is  reached 
the  flame  bursts  into  song.  The  other  flames  are  still 
silent  within  their  tubes.  But  by  urging  the  instrument 
on  to  higher  notes,  the  second  flame  is  started,  and  the 
third  alone  remains.  A  still  higher  note  starts  it  also. 
Thus,  as  the  sound  of  the  syren  rises  gradually  in  pitch,  it 
awakens  every  flame  in  passing,  by  striking  it  with  a  series 
of  waves  whose  periods  of  recurrence  are  similar  to  its 
own. 

Now  the  wave-motion  from  the  syren  is  in  part  taken 
up  by  the  flame  which  synchronizes  with  the  waves;  and  were 
these  waves  to  impinge  upon  a  multitude  of  flames,  instead 
of  upon  one  flame  only,  the  transference  might  be  so 
great  as  to  absorb  the  whole  of  the  orignal  wave  motion. 
Let  us  apply  these  facts  to  radiant  heat.  This  blue  flame 
is  the  flame  of  carbonic  oxide:  this  transparent  gas  is  car- 
bonic acid  gas.  In  the  blue  flame  we  have  carbonic  acid 
intensely  heated,  or,  in  other  words,  in  a  state  of  intense 
vibration.  It  thus  resembles  the  sounding  fork,  while  this 
cold  carbonic  acid  resembles  the  silent  one.  What  is  the 
consequence?  Through  the  synchronism  of  the  hot  and 
cold  gas,  the  waves  emitted  by  the  former  are  intercepted 
by  the  latter,  the  transmission  of  the  radiant  heat  being 
thus  prevented.  The  cold  gas  is  intensely  opaque  to  the 
radiation  from  this  particular  flame,  though  highly  trans- 
parent to  heat  of  every  other  kind.  We  are  here  manifestly 
dealing  with  that  great  principle  which  lies  at  the  basis  of 
.spectrum  analysis,  and  which  has  enabled  scientific  men  to 
determine  the  substances  of  which  the  sun,  the  stars,  and 
even  the  nebulae  are  composed;  the  principle,  namely,  that 
a  body  which  is  competent  to  emit  any  ray,  whether  of 
heat  or  light,  is  competent  in  the  same  degree  to  absorb 


62  FRAGMENTS  OF  SCIENCE. 

that  ray.  The  absorption  depends  on  the  synchronism 
existing  between  the  vibrations  of  the  atoms  from  which 
the  rays,  or  more  correctly  the  waves,  issue,  and  those  of 
the  atoms  on  which  they  impinge. 

To  its  almost  total  incompetence  to  emit  white  light, 
aqueous  vapor  adds  a  similar  incompetence  to  absorb  white 
light.  It  cannot,  for  example,  absorb  the  luminous  rays 
of  the  sun,  though  it  can  absorb  the  non-luminous  rays  of 
the  earth.  This  incompetence  of  the  vapor  to  absorb  lumi- 
nous rays  is  shared  by  water  and  ice — in  fact,  by  all  really 
transparent  substances.  Their  transparency  is  due  to 
their  inability  to  absorb  luminous  rays.  The  molecules  of 
such  substances  are  in  dissonance  with  the  luminous 
waves;  and  hence  such  waves  pass  through  transparent 
bodies  without  disturbing  the  molecular  rest.  A  purely 
luminous  beam,  however  intense  may  be  its  heat,  is  sensi- 
bly incompetent  to  melt  ice.  We  can,  for  example,  con- 
verge a  powerful  luminous  beam  upon  a  surface  covered 
with  hoar  frost,  without  melting  a  single  spicula  of  the 
crystals.  How  then,  it  niay  be  asked,  are  the  snows  of  the 
Alps  swept  away  by  the  sunshine  of  summer?  I  answer, 
they  are  not  swept  away  by  sunshine  at  all,  but  by 
rays  winch  have  no  sunshine  whatever  in  them.  The 
luminous  rays  of  the  sun  fall  upon  the  snow-fields  and  are 
flashed  in  echoes  from  crystal  to  crystal,  but  they  find 
next  to  no  lodgment  within  the  crystals.  They  are  hardly 
at  all  absorbed,  and  hence  they  cannot  produce  fusion. 
But  a  body  of  powerful  dark  rays  is  emitted  by  the  sun; 
and  it  is  these  that  cause  the  glaciers  to  shrink  and  the 
snows  to  disappear;  it  is  they  that  fill  the  banks  of  the 
Arve  and  Arveyron,  and  liberate  from  their  frozen  cap- 
tivity the  Rhone  and  the  Rhine. 

Placing  a  concave  silvered  mirror  behind  the  electric 
light  its  rays  are  converged  to  a  focus  of  dazzling  brilliancy. 
Placing  in  the  path  of  the  rays,  between  the  light  and  the 
focus,  a  vessel  of  water,  and  introducing  at  the  focus  a 
piece  of  ice,  the  ice  is  not  melted  by  the  concentrated  beam. 
Matches,  at  the  same  place,  are  ignited,  and  wood  is  set 
on  fire.  The  powerful  heat,  then,  of  this  luminous  beam 
is  incompetent  to  melt  the  ice.  On  withdrawing  the  cell 
of  water,  the  ice  immediately  liquefies,  and  the  water 
trickles  from  it  in  drops.  Reintroducing  the  cell  of  water, 
the  fusion  is  arrested,  and  the  drops  cease  to  fall.  The 


ON  RA  DIANT  HEA  T.  63 

transparent  water  of  the  cell  exerts  no  sensible  absorption 
on  the  luminous  rays,  still  it  withdraws  something  from 
the  beam,  which,  when  permitted  to  act,  is  competent  to 
melt  the  ice.  This  something  is  the  dark  radiation  of  the 
electric  light.  Again,  I  place  a  slab  of  pure  ice  in  front 
of  the  electric  lamp:  send  a  luminous  beam  first  through 
our  cell  of  water  and  then  through  the  ice.  By  means  of 
a  lens  an  image  of  the  slab  is  cast  upon  a  white  screen. 
The  t»eam,  sifted  by  the  water,  lias  little  power  upon  the 
ice.  But  observe  what  occurs  when  the  water  is  removed; 
we  have  here  a  star  and  there  a  star,  each  star  resembling 
a  flower  of  six  petals,  and  growing  visibly  larger  before  our 
eyes.  As  the  leaves  enlarge,  their  edges  become  serrated, 
but  there  is  no  deviation  from  the  six-rayed  type.  We 
have  here,  in  fact,  the  crystallization  of  the  ice  reversed 
by  the  invisible  rays  of  the  electric  beam.  They  take  the 
molecules  down  in  this  wonderful  way,  and  reveal  to  us 
the  exquisite  atomic  structure  of  the  substance  with  which 
Nature  every  winter  roofs  our  ponds  and  lakes. 

Numberless  effects,  apparently  anomalous,  might  be 
adduced  in  illustration  of  the  action  of  these  lightless  rays. 
These  two  powders,  for  example,  are  both  white,  and  un- 
distinguishable  from  each  other  by  the  eye.  The  luminous 
rays  of  the  sun  are  unabsorbed  by  both — from  such  rays 
these  powders  acquire  no  heat;  still  one  of  them,  sugar,  is 
heated  so  highly  by  the  concentrated  beam  of  the  electric 
lamp,  that  it  first  smokes  and  then  violently  inflames,  while 
the  other  substance,  salt,  is  barely  warmed  at  the  focus. 
Placing  two  perfectly  transparent  liquids  in  test-tubes  at 
the  focus,  one  of  them  boils  in  a  couple  of  seconds,  while 
the  other,  in  a  similar  position,  is  hardly  warmed.  The 
boiling-point  of  the  first  liquid  is  78  degrees  C.,  which  is 
speedily  reached;  that  of  the  second  liquid  is  only  48 
degrees  C.,  which  is  never  reached  at  all.  These  anomalies 
are  entirely  due  to  the  unseen  element  which  mingles  with 
the  luminous  rays  of  the  electric  beam,  and  indeed  consti- 
tutes 90  per  cent,  of  its  calorific  power. 

A  substance,  as  many  of  you  know,  has  been  discovered, 
by  which  these  dark  rays  may  be  detached  from  the  total 
emission  of  the  electric  lamp.  This  ray-filter  is  a  liquid, 
black  as  pitch  to  the  luminous,  but  bright  as  a  diamond  to 
the  non-luminous,  radiation.  It  mercilessly  cuts  off  the 
former,  but  allows  the  latter  free  transmission.  When 


64  FRAGMENTS  OP  SCIENCE. 

these  invisible  rays  are  brought  to  a  focus,  at  a  distance  of 
several  feet  from  the  electric  lamp,  the  dark  rays  form  an 
invisible  image  of  their  source.  By  proper  means,  this 
image  may  be  transformed  into  a  visible  one  of  dazzling 
brightness.  It  might,  moreover,  be  shown,  if  time  per- 
mitted, how,  out  of  those  perfectly  dark  rays,  could  be  ex- 
tracted, by  a  process  of  transmutation,  all  the  colors  of  the 
solar  spectrum.  It  might  also  be  proved  that  those  rays, 
powerful  as  they  are,  and  sufficient  to  fuse  many  metals, 
can  be  permitted  to  enter  the  eye,  and  to  break  upon  the 
retina,  without  producing  the  least  luminous  impression. 

The  dark  rays  being  thus  collected,  you  see  nothing  at 
their  place  of  convergence.  With  a  proper  thermometer  it 
could  be  proved  that  even  the  air  at  the  focus  is  just  as 
cold  as  the  surrounding  air.  And  mark  the  conclusion  to 
which  this  leads.  It  proves  the  ether  at  the  focus  to  be 
practically  detached  from  the  air — that  the  most  violent 
ethereal  motion  may  there  exist,  without  the  least  aerial 
motion.  But,  though  you  see  it  not,  there  is  sufficient 
heat  at  that  focus  to  set  London  on  fire.  The  heat  there 
is  competent  to  raise  iron  to  a  temperature  at  which  it 
throws  off  brilliant  scintillations.  It  can  heat  platinum  to 
whiteness,  and  almost  fuse  that  refractory  metal.  It 
actually  can  fuse  gold,  silver,  copper,  and  aluminium.  The 
moment,  moreover,  that  wood  is  placed  at  the  focus  it 
bursts  into  a  blaze. 

It  has  been  already  affirmed  that,  whether  as  regards 
radiation  or  absorption,  the  elementary  atoms  possess  but 
little  power.  This  might  be  illustrated  by  a  long  array  of 
facts;  and  one  of  the  most  singular  of  these  is  furnished 
by  the  deportment  of  that  extremely  combustible  substance, 
phosphorus,  when  placed  at  the  dark  focus.  It  is 
impossible  to  ignite  there  a  fragment  of  amorphous  phos- 
phorus. But  ordinary  phosphorus  is  a  far  quicker 
combustible,  and  its  deportment  toward  radiant  heat  is  still 
more  impressive.  It  may  be  exposed  to  the  intense  radia- 
tion of  an  ordinary  fire  without  bursting  into  flame.  It 
may  also  be  exposed  for  twenty  or  thirty  seconds  at  an 
obscure  focus,  of  sufficient  power  to  raise  platinum  to  a 
red  heat,  without  ignition.  Notwithstanding  the  energy 
of  the  ethereal  waves  here  concentrated,  notwithstanding 
the  extremely  inflammable  character  of  the  elementary  body 
exposed  to  their  action,  the  atoms  of  that  body  refuse  to 


ON  RADIANT  HEAT.  65 

partake  of  the  motion  of  the  powerful  waves  of  low  refrangi- 
bility,  and  consequently  cannot  be  affected  by  their  heat. 

The  knowledge  we  now  possess  will  enable  us  to  analyze 
with  profit  a  practical  question.  White  dresses  are  worn 
in  summer,  because  they  are  found  to  be  cooler  than  dark 
ones.  The  celebrated  Benjamin  Franklin  placed  bits  of 
cloth  of  various  colors  upon  snow,  exposed  them  to  direct 
sunshine,  and  found  that  they  sank  to  different  depths  in 
the  snow.  The  black  cloth  sank  deepest,  the  white  did 
not  sink  at  all.  Franklin  inferred  from  this  experiment 
that  black  bodies  are  the  best  absorbers,  and  white  ones  the 
worst  absorbers,  of  radiant  heat.  Let  usiest  the  generality 
of  this  conclusion.  One  of  these  two  cards  is  coated  with 
a  very  dark  powder,  and  the  other  with  a  perfectly  white 
one.  I  place  the  powdered  surfaces  before  a  fire,  and 
leave  them  there  until  they  have  acquired  as  high  a  tem- 
perature as  they  can  attain  in  this  position.  Which  of  the 
cards  is  then  most  highly  heated?  It  requires  no  ther- 
mometer to  answer  this  question.  Simply  pressing  the 
back  of  the  card,  on  which  the  white  powder  is  strewn, 
against  the  cheek  or  forehead,  it  is  found  intolerably  hot. 
Placing  the  dark  card  in  the  same  position,  it  is  found 
cool.  The  white  powder  has  absorbed  far  more  heat  than 
the  dark  one.  This  simple  result  abolishes  a  hundred  con- 
clusions which  have  been  hastily  drawn  from  the  experi- 
ment of  Franklin.  Again,  here  are  suspended  two  delicate 
mercurial  thermometers  at  the  same  distance  from  a  gas- 
flame.  The  bulb  of  one  of  them  is  covered  by  a  dark  sub- 
stance, the  bulb  of  the  other  by  a  white  one.  Both  bulbs 
have  received  the  radiation  from  the  flame,  but  the  white 
bulb  has  absorbed  most,  and  its  mercury  stands  much 
higher  than  that  of  the  other  thermometer.  This  experi- 
ment might  be  varied  in  a  hundred  ways:  it  proves  that 
from  the  darkness  of  a  body  you  can  draw  no  certain  con- 
clusion regarding  its  power  of  absorption. 

The  reason  of  this  simply  is,  that  color  gives  us  intelli- 
gence of  only  one  portion,  and  that  the  smallest  one,  of  the 
rays  impinging  on  the  colored  body.  Were  the  rays  all 
luminous,  we  might  with  certainty  infer  from  the  color  of 
a  body  its  power  of  absorption;  but  the  great  mass  of  the 
radiation  from  our  fire,  our  gas-flame,  and  even  from  the 
sun  itself,  consists  of  invisible  calorific  rays,  regarding 
which  color  teaches  us  nothing.  A  body  may  be  highly 


6g  FRAGMENTS  OF  SCIENCE. 

transparent  to  the  one  class  of  rays,  and  highly  opaque  to 
the  other.  Thus  the  white  powder,  which  has  shown 
itself  so  powerful  an  absorber,  has  been  specially  selected 
on  account  of  its  extreme  perviousness  to  the  visible  rays, 
and  its  extreme  irnperviousness  to  the  invisible  ones;  while 
the  dark  powder  was  chosen  on  account  of  its  extreme 
transparency  to  the  invisible,  and  its  extreme  opacity  to 
the  visible  rays.  In  the  case  of  the  radiation  from  our 
fire,  about  98  per  cent,  of  the  whole  emission  consists  of 
invisible  rays;  the  body,  therefore,  which  was  most  opaque 
to  these  triumphed  as  an  absorber,  though  that  body  was 
a  white  one. 

And  here  it  is  worth  while  to  consider  the  manner  in 
which  we  obtain  from  natural  facts  what  may  be  called  their 
intellectual  value.  Throughout  the  processes  of  Nature 
we  have  interdependence  and  harmony;  and  the  main 
value  of  physics,  considered  as  a  mental  discipline,  consists 
in  the  tracing  out  of  this  interdependence,  and  the  demon- 
stration of  this  harmony.  The  outward  and  visible  phe- 
nomena are  the  counters  of  the  intellect;  and  our  science 
would  not  be  worthy  of  its  name  and  fame  if  it  halted  at 
facts,  however  practically  useful,  and  neglected  the  laws 
which  accompany  and  rule  the  phenomena.  Let  us  en- 
deavor, then,  to  extract  from  the  experiment  of  Franklin 
all  that  it  can  yield,  calling  to  our  aid  the  knowledge  which 
our  predecessors  have  already  stored.  Let  us  imagine  two 
pieces  of  cloth  of  the  same  texture,  the  one  black  and  the 
other  white,  placed  upon  sunned  snow.  Fixing  our  atten- 
tion on  the  white  piece,  let  us  inquire  whether  there  is  any 
reason  to  expect  that  it  will  sink  in  the  snow  at  all.  There 
is  knowledge  at  hand  which  enables  us  to  reply  at  once  in 
the  negative.  There  is,  on  the  contrary,  reason  to  expect 
that,  after  a  sufficient  exposure,  the  bit  of  cloth  will  be 
found  on  an  eminence  instead  of  in  a  hollow;  that  instead 
of  a  depression,  we  shall  have  a  relative  elevation  of  the 
bit  of  cloth.  For,  as  regards  the  luminous  rays  of  the 
sun,  the  cloth  and  the  snow  are  alike  powerless;  the  one 
cannot  be  warmed,  nor  the  other  melted,  by  such  rays. 
The  cloth  is  white  and  the  snow  is  white,  because  their 
confusedly  mingled  fibers  and  particles  are  incompetent  to 
absorb  the  luminous  rays.  Whether,  then,  the  cloth  will 
sink  or  not  depends  entirely  upon  the  dark  rays  of  the  sun. 
the  substance  which  absorbs  these  dark  rays  with  the 


ON  RADIANT  HE  A  T.  67 

greatest  avidity  is  ice — or  snow,  which  is  merely  ice  in 
powder.  Hence,  a  less  amount  of  heat  will  be  lodged  in 
the  cloth  than  in  the  surrounding  snow.  The  cloth  must 
therefore  act  as  a  shield  to  the  snow  on  which  it  rests;  and, 
in  consequence  of  the  more  rapid  fusion  of  the  exposed 
snow,  its  shield  must,  in  due  time,  be  left  behind,  perched 
upon  an  eminence  like  a  glacier-table. 

But  though  the  snow  transcends  the  cloth,  both  as  a 
radiator  and  absorber,  it  does  not  much  transcend  it. 
Cloth  is  very  powerful  in  both  these  respects.  Let  us  now 
turn  our  attention  to  the  piece  of  black  cloth,  the  texture 
and  fabric  of  which  I  assume  to  be  the  same  as  that  of  the 
white.  For,  our  object  being  to  compare  the  effects  of 
color,  we  must,  in  order  to  study  this  effect  in  its  purity, 
preserve  all  the  other  conditions  constant.  Let  us  then 
suppose  the  black  cloth  to  be  obtained  from  the  dyeing  of 
the  white.  The  cloth  itself,  without  reference  to  the  dye, 
is  nearly  as  good  an  absorber  of  heat  as  the  snow  around  it. 
But  to  the  absorption  of  the  dark  solar  rays  by  the  undyed 
cloth,  is  now  added  the  absorption  of  the  whole  of  the 
luminous  rays,  and  this  great  additional  influx  of  heat  is 
far  more  than  sufficient  to  turn  the  balance  in  favor  of  the 
black  cloth.  The  sum  of  its  actions  on  the  dark  and 
luminous  rays  exceeds  the  action  of  the  snow  on  the  dark 
rays  alone.  Hence  the  cloth  will  sink  in  the  snow,  and 
this  is  the  complete  analysis  of  Franklin's  experiment. 

Throughout  this  discourse  the  main  stress  has  been  laid 
on  chemical  constitution,  as  influencing  most  powerfully 
the  phenomena  of  radiation  and  absorption.  With  regard 
to  gases  and  vapors,  and  to  the  liquids  from  which  these 
vapors  are  derived,  it  has  been  proved  by  the  most  varied 
and  conclusive  experiments  that  the  acts  of  radiation  and 
absorption  are  molecular — that  they  depend  upon  chemical, 
and  not  upon  mechanical  condition.  In  attempting  to 
extend  this  principle  to  solids  I  was  met  by  a  multitude  of 
facts,  obtained  by  celebrated  experimenters,  which  seemed 
flatly  to  forbid  such  an  extension.  Melloui,  for  example, 
had  "fount]  the  same  radiant  and  absorbent  power  for  chalk 
and  lampblack.  MM.  Masson  and  Courtepee  had  per- 
formed a  most  elaborate  series  of  experiments  on  chemical 
precipitates  of  various  kinds,  and  found  that  they  one  and 
all  manifested  the  same  power  of  radiation.  They  con- 
cluded from  their  researches,  that  when  bodies  are  reduced 


68  FRAGMENTS  OF  SCIENCE. 

to  an  extremely  fine  state  ef  division,  the  influence  of  this 
state  is  so  powerful  as  entirely  to  mask  and  override  what- 
ever influence  may  be  due  to  chemical  constitution. 

But  it  appears  to  me  that  through  the  whole  of  these 
researches  an  oversight  has  run,  the  mere  mention  of 
which  will  show  what  caution  is  essential  in  the  opera- 
tions of  experimental  philosophy;  while  an  experiment  or 
two  will  make  clear  wherein  the  oversight  consists.  Fill- 
ing a  brightly  polished  metal  cube  with  boiling  water,  I 
determine  the  quantity  of  heat  emitted  by  two  of  the 
bright  surfaces.  As  a  radiator  of  heat  one  of  them  far 
transcends  the  other.  Both  surfaces  appear  to  be  metallic; 
what,  then,  is  the  cause  of  the  observed  difference  in  their 
radiative  power?  Simply  this:  one  of  the  surfaces  is 
coated  with  transparent  gum,  through  which,  of  course,  is 
seen  the  metallic  luster  behind;  and  this  varnish,  though 
so  perfectly  transparent  to  luminous  rays,  is  as  opaque  as 
pitch,  or  lampblack,  to  non-luminous  ones.  It  is  a 
powerful  emitter  of  dark  rays;  it  is  also  a  powerful  ab- 
sorber. While,  therefore,  at  the  present  moment,  it  is 
copiously  pouring  forth  radiant  heat  itself,  it  does  not 
allow  a  single  ray  from  the  metal  behind  to  pass  through 
it.  The  varnish  then,  and  not  the  metal,  is  the  real 
radiator. 

Now  Melloni,  and  Masson,  and  Courtepee  experimented 
thus:  they  mixed  their  powders  and  precipitates  with  gum- 
water,  and  laid  them,  by  means  of  a  brush,  upon  the  sur- 
faces of  a  cube  like  this.  True,  they  saw  their  red  pow- 
ders red,  their  white  ones  white,  and  their  black  ones 
black,  but  they  saw  these  colors  through  the  coat  of  var- 
nish which  surrounded  every  particle.  When,  therefore,  it 
was  concluded  that  color  had  no  influence  on  radiation,  no 
chance  had  been  given  to  it  of  asserting  its  influence; 
when  it  was  found  that  all  chemical  precipitates  radiated 
alike,  it  was  the  radiation  from  a  varnish,  common  to 
them  all,  which  showed  the  observed  constancy.  Hun- 
dreds, perhaps  thousands,  of  experiments  on  radiant  heat 
have  been  performed  in  this  way,  by  various  inquirers, 
but  the  work  will,  I  fear,  have  to  be  done  over  again.  I 
am  not,  indeed,  acquainted  with  an  instance  in  which  an 
oversight  of  so  trivial  a  character  has  been  committed  by 
so  many  able  men  in  succession,  vitiating  so  large  an 
amount  of  otherwise  excellent  work. 


ON  RADIANT  HEAT.  69 

Basing  our  reasonings  thus  on  demonstrated  facts,  we 
arrive  at  the  extremely  probable  conclusion  that  the  envel- 
ope of  the  particles,  and  not  the  particles  themselves,  was 
the  real  radiator  in  the  experiments  just  referred  to.  To 
reason  thus  and  deduce  their  more  or  less  probable  conse- 
quences from  experimental  facts,  is  an  incessant  exercise 
of  the  student  of  physical  science.  But  having  thus 
followed,  for  a  time,  the  light  of  reason  alone  through  a 
series  of  phenomena,  and  emerged  from  them  with  a  purely 
intellectual  conclusion,  our  duty  is  to  bring  tiiat  conclusion 
to  an  experimental  test.  In  this  way  we  fortify  our 
science. 

For  the  purpose  of  testing  our  conclusion  regarding  the 
influence  of  the  gum,  I  take  two  powders  presenting  the 
same  physical  appearance  ;  one  of  them  is  a  compound  of 
mercury,  and  the  other  a  compound  of  lead.  On  two  sur- 
faces of  a  cube  are  spread  these  bright  red  powders,  with- 
out varnish  of  any  kind.  Filling  the  cube  with  boiling 
water,  and  determining  the  radiation  from  the  two  sur- 
faces, one  of  them  is  found  to  emit  thirty-nine  units  of 
heat,  while  the  other  emits  seventy-four.  This,  surely,  is  a 
great  difference.  Here,  however,  is  a  second  cube,  having 
two  of  its  surfaces  coated  with  the  same  powders,  the  only 
difference  being  that  the  powders  are  laid  on  by  means  of 
a  transparent  gum.  Both  surfaces  are  now  absolutely 
alike  in  radiative  power.  Both  of  them  emit  somewhat 
more  than  was  emitted  by  either  of  the  unvarnished  pow- 
ders, simply  because  the  gum  employed  is  a  better  radiator 
than  either  of  them.  Excluding  all  varnish,  and  compar- 
ing white  with  white,  vast  differences  are  found;  compar- 
ing black  with  black,  they  are  also  different;  and  when 
black  and  white  are  compared,  in  some  cases  the  black 
radiates  far  more  than  the  white,  while  in  other  cases  the 
white  radiates  far  more  than  the  black.  Determining,  more- 
over,the  absorptive  power  of  those  powders,  it  is  found  to  go 
hand-in-hand  with  their  radiative  power.  The  good 
radiator  is  a  good  absorber,  and  the  bad  radiator  is  a  bad 
absorber.  From  all  this  it  is  evident  that  as  regards  the 
radiation  and  absorption  of  non-luminous  heat,  color 
teaches  us  nothing;  and  that  even  as  regards  the  radiation 
of  the  sun,  consisting  as  it  does  mainly  of  non-luminous 
rays,  conclusions  as  to  the  influence  of  color  may  be  alto- 
gether delusive.  This  is  the  strict  scientific  upshot  of  our 


70  FRAGMENTS  OF  SCIENCE. 

researches.  But  it  is  not  the  less  true  that  in  the  case  of 
wearing  apparel— and  this  for  reasons  which  I  have  given 
in  analyzing  the  experiment  of  Franklin — black  dresses  are 
more  potent  than  white  ones  as  absorbers  of  solar  heat. 

Thus,  in  brief  outline,  have  been  brought  before  you  a 
few  of  the  results  of  recent  inquiry.  If  you  ask  me  what 
is  the  use  of  them,  I  can  hardly  answer  you,  unless  you 
define  the  term  use.  If  you  meant  to  ask  whether  those 
dark  rays  which  clear  away  the  Alpine  snows,  will  ever  be 
applied  to  the  roasting  of  turkeys,  or  the  driving  of  steam- 
engines— while  affirming  their  power  to  do  both,  I  would 
frankly  confess  that  they  are  not  at  present  capable  of 
competing  profitably  with  coal  in  these  particulars.  Still 
they  may  have  great  uses  unknown  to  me;  and  when  our 
coal-fields  are  exhausted,  it  is  possible  that  a  more  ethereal 
race  than  we  are  may  cook  their  victuals,  and  perform  their 
work,  in  this  transcendental  way.  But  is  it  necessary  that 
the  student  of  science  should  have  his  labors  tested  by 
their  possible  practical  applications?  What  is  the  prac- 
tical value  of  Homer's  Iliad?  You  smile,  and  possibly 
think  that  Homer's  Iliad  is  good  as  a  means  of  culture. 
There's  the  rub.  The  people  who  demand  of  science  prac- 
tical uses,  forget,  or  do  not  know,  that  it  also  is  great  as  a 
means  of  culture — that  the  knowledge  of  this  wonderful 
universe  is  a  thing  profitable  in  itself,  and  requiring  no 
practical  application  to  justify  its  pursuit. 

But  while  the  student  of  nature  distinctly  refuses  to 
have  his  labors  judged  by  their  practical  issues  unless  the 
term  practical  be  made  to  include  mental  as  well  as 
material  good,  he  knows  full  well  that  the  greatest  prac- 
tical triumphs  have  been  episodes  in  the  search  after  pure 
natural  truth.  The  electric  telegraph  is  the  standing 
wonder  of  this  age,  and  the  men  whose  scientific  knowledge, 
and  mechanical  skill,  have  made  the  telegraph  what  it  is, 
are  deserving  of  all  honor.  In  fact,  they  have  had  their 
reward,  both  in  reputation  and  in  those  more  substantial 
benefits  which  the  direct  service  of  the  public  always  car- 
ries in  its  train.  But  who,  I  would  ask,  put  the  soul  into 
this  telegraphic  body?  Who  snatched  from  heaven  the 
fire  that  flashes  along  the  line?  This,  I  am  bound  to  say, 
was  done  by  two  men,  the  one  a  dweller  in  Italy,*  the 

*Volta. 


NEW  CHEMICAL  REACTIONS.  71 

other  a  dweller  in  England,*  who  never  in  their  inquiries 
consciously  set  a  practical  object  before  them — whose  only 
stimulus  was  the  fascination  which  draws  the  climber  to  a 
never-trodden  peak,  and  would  have  made  Csesar  quit  his 
victories  for  the  sources  of  the  Nile.  That  the  knowl- 
edge brought  to  us  by  those  prophets,  priests,  and  kings 
of  science  is  what  the  world  calls  "  useful  knowledge,"  the 
triumphant  application  of  their  discoveries  proves.  But 
science  has  another  function  to  fulfill,  in  the  storing  and 
the  training  of  the  human  mind;  and  I  would  base  my 
appeal  to  you  on  the  specimen  which  has  this  evening  been 
brought  before  you,  whether  any  system  of  education  at 
the  present  day 'can  be  deemed  even  approximately  com- 
plete, in  which  the  knowledge  of  Nature  is  neglected  or 
ignored. 


CHAPTER  IV. 

NEW  CHEMICAL  REACTIONS   PRODUCED  BY  LIGHT. 

1868-69. 

MEASURED  by  their  power,  not  to  excite  vision,  but  to 
produce  heat — in  other  words,  measured  by  their  absolute 
energy — the  ultra-red  waves  of  the  sun  and  of  the  electric 
light,  as  shown  in  the  preceding  articles,  far  transcend  the 
visible.  In  the  domain  of  chemistry,  however,  there  are 
numerous  cases  in  which  the  more  powerful  waves  are 
ineffectual;  while  the  more  minute  waves,  through  what 
may  be  called  their  timeliness  of  application,  are  able  to 
produce  great  effects.  A  series  of  these,  of  a  novel  and 
beautiful  character,  discovered  in  1868,  and  further  illus- 
trated in  subsequent  years,  may  be  exhibited  by  subjecting 
the  vapors  of  volatile  liquids  to  the  action  of  concentrated 
sunlight,  or  to  the  concentrated  beam  of  the  electric  light. 
Their  investigation  led  up  to  the  discourse  on  "Dust  and 
Disease"  which  follows  in  this  volume  ;  and  for  this  reason 
some  account  of  them  is  introduced  here. 

*  Faraday. 


72  FRAGMENTS  OF  SCIENCE. 

A  glass  tube  3  feet  long  and  3  inches  wide,  which  had 
been   frequently   employed  in  my   researches   on  radiant 
heat,  was  supported  horizontally  on   two  stands.     At  one 
end  of  the  tube  was  placed  an  electric  lamp,   the  height 
and  position  of  both  being  so  ar- 
Fie.2.  ranged    that  the  axis  of  the  tube, 

and  that  of  the  beam  issuing  from 
the  lamp,  were  coincident.  In  the 
first  experiments  the  two  ends  of 
the  tube  were  closed  by  plates  of 
rock-salt  and  subsequently  by  plates 
of  glass.  For  the  sake  of  distinc- 
tion, I  call  this  tube  the  experi- 
mental tube.  It  was  connected  with 
an  air-pump,  and  also  with  a  series 
of  drying  and  other  tubes  used 
for  the  purification  of  the  air. 

A  number  of  test-tubes,  like  F, 
fig.  2  (I  have  used  at  least  fifty 
of  them),  were  converted  into 
Woulf's  flasks.  Each  of  them  was 
stopped  by  a  cork,  through  which 
passed  two  glass  tubes:  one  of  these 
tubes  (a)  ended  immediately  below 
the  cork,  while  the  other  (b)  de- 
scended to  the  bottom  of  the  flask, 
being  drawn  out  at  its  lower  end  to 
an  orifice  about  0.03  of  an  inch  in 
diameter.  It  was  found  necessary 
to  coat  the  cork  carefully  with 
cement.  In  the  later  experiments 
corks  of  vulcanized  india-rubber 
were  invariably  employed. 
The  little  flask,  thus  formed,  being  partially  filled  with 
the  liquid  whose  vapor  was  to  be  examined,  was  introduced 
into  the  path  of  the  purified  current  of  air.  The  experi- 
mental tube  being  exhausted,  and  the  cock  which  cut  off 
the  supply  of  purified  air  being  cautiously  turned  on,  the 
air  entered  the  flask  through  the  tube  b,  and  escaped  by 
the  small  orifice  at  the  lower  end  of  b  into  the  liquid. 
Through  this  it  bubbled,  loading  itself  with  vapor,  after 
which  the  mixed  air  and  vapor,  passing  from  the  flask  by 
the  tube  a,  entered  the  experimental  tube,  where  they 
were  subjected  to  the  action  of  light. 


NEW  CHEMICAL  REACTIONS.  73 


74  FRAGMENTS  OF  SCIENCE. 

The  whole  arrangement  is  shown  in  fig.  3,  where  L 
represents  the  electric  lamp,  s  s'  the  experimental  tube, pp 
the  pipe  leading  to  the  air-pump,  and  F  the  test-tube  con- 
taining the  volatile  liquid.  The  tube  t  t'  is  plugged  with 
cotton-wool  intended  to  intercept  the  floating  matter  of 
the  air;  the  bent  tube  T'  contains  caustic  potash,  the  tube 
T  sulphuric  acid,  the  one  intended  to  remove  the  carbonic 
acid  and  the  other  the  aqueous  vapor  of  the  air. 

The  power  of  the  electric  beam  to  reveal  the  existence  of 
anything  within  the  experimental  tube,  or  the  impurities 
of  the  tube  itself,  is  extraordinary.  When  the  experiment 
is  made  in  a  darkened  room,  a  tube  which  in  ordinary  day- 
light appears  absolutely  clean,  is  often  shown  by  the 
present  mode  of  examination  to  be  exceedingly  filthy. 

The  following  are  some  of  the  results  obtained  with  this 
arrangement: 

Nitrite  of  amyl. — The  vapor  of  this  liquid  was  in  the 
first  instance  permitted  to  enter  the  experimental  tube, 
while  the  beam  from  the  electric  lamp  was  passing  through 
it.  Curious  clouds,  the  cause  of  which  was  then  unknown, 
were  observed  to  form  near  the  place  of  entry,  being 
afterward  whirled  through  the  tube. 

The  tube  being  again  exhausted,  the  mixed  air  and  vapor 
were  allowed  to  enter  it  in  the  dark.  The  slightly  conver- 
gent beam  of  the  electric  light  was  then  sent  through  the 
mixture. 

For  a  moment  the  tube  was  optically  empty,  nothing 
whatever  being  seen  within  it;  but  before  a  second  had 
elapsed  a  shower  of  particles  was  precipitated  on  the  beam. 
The  cloud  thus  generated  became  denser  as  the  light  con- 
tinued to  act,  showing  at  some  places  vivid  iridescence. 

The  lens  of  the  electric  lamp  was  now  placed  so  as  to 
form  within  the  tube  a  strongly  convergent  cone  of  rays. 
The  tube  was  cleansed  and  agam  filled  in  darkness.  When 
the  light  was  sent  through  it,  the  precipitation  upon  the 
beam  was  so  rapid  and  intense  that  the  cone,  which  a 
moment  before  was  invisible,  flashed  suddenly  forth  like  a 
solid  luminous  spear.  The  effect  was  the  same  when  the 
air  and  vapor  were  allowed  to  enter  the  tube  in  diffuse  day- 
light. The  cloud,  however,  which  shone  with  such 
extraordinary  radiance  under  the  electric  beam,  was  in- 
visible in  the  ordinary  light  of  the  laboratory. 

The  quantity  of  mixed  air  and  vapor  within  the  experi- 


NEW  CHEMICAL  REACTIONS.  ?5 

mental  tube  could  of  course  be  regulated  at  pleasure.  The 
rapidity  of  the  action  diminished  with  the  attenuation  of 
the  vapor.  When,  for  example,  the  mercurial  column 
associated  with  the  experimental  tube  was  depressed  only 
five  inches,  the  action  was  not  nearly  so  rapid  as  when  the 
tube  was  full.  In  such  cases,  however,  it  was  exceedingly 
interesting  to  observe,  after  some  seconds  of  waiting,  a  thin 
streamer  of  delicate  bluish-white  cloud  slowly  forming 
along  the  axis  of  the  tube,  and  finally  swelling  so  as  to 
fill  it. 

When  dry  oxygen  was  employed  to  carry  in  the  vapor, 
the  effect  was  the  same  as  that  obtained  with  air. 

When  dry  hydrogen  was  used  as  a  vehicle,  the  effect  was 
also  the  same. 

The  effect,  therefore,  is  not  due  to  any  interaction  be- 
tween the  vapor  of  the  nitrite  and  its  vehicle. 

This  was  further  demonstrated  by  the  deportment  of  the 
vapor  itself.  When  it  was  permitted  to  enter  the  experi- 
mental tube  unmixed  with  air  or  any  other  gas,  the  effect 
was  substantially  the  same.  Hence  the  seat  of  the  observed 
action  is  the  vapor. 

This  action  is  not  to  be  ascribed  to  heat.  As  regards  the 
glass  of  the  experimental  tube,  and  the  air  within  the  tube, 
the  beam  employed  in  these  experiments  was  perfectly  cold. 
It  had  been  sifted  by  passing  it  through  a  solution  of  alum, 
and  through  the  thick  double-convex  lens  of  the  lamp. 
When  the  unsifted  beam  of  the  lamp  was  employed,  the 
effect  was  still  the  same;  the  obscure  calorific  rays  did  not 


y  object  here  being  simply  to  point  out  to  chemists  a 


appear  to  interfere  with  the  result. 

My 

method  of  experiment  which  reveals  a  new  and  beautiful 
series  of  reactions,  I  left  to  them  the  examination  of  the 
products  of  decomposition.  The  group  of  atoms  forming 
the  molecule  of  nitrite  of  amyl  is  obviously  shaken  asunder 
by  certain  specific  waves  of  the  electric  beam,  nitric  oxide 
and  other  products,  of  which  the  nitrate  of  amyl  is  probably 
one,  being  the  result  of  the  decomposition.  The  brown 
fumes  of  nitrous  acid  were  seen  mingling  with  the  cloud 
within  the  experimental  tube.  The  nitrate  of  amyl,  being 
less  volatile  than  the  nitrite,  and  not  being  able  to  maintain 
itself  in  the  condition  of  vapor,  would  be  precipitated  as  a 
visible  cloud  along  the  track  of  the  beam. 

In  the  anterior  portions  of  the  tube  a  powerful  sifting  of 


76  FRAGMENTS  OF  SCIENCE. 

the  beam  by  the  vapor  occurs,  which  diminishes  the  chem- 
ical action  in  the  posterior  portions.  In  some  experiments 
the  precipitated  cloud  only  extended  halfway  down  the 
tube.  When,  under  these  circumstances,  the  lamp  was 
shifted  so  as  to  send  the  beam  through  the  other  end  of  the 
tube,  copious  precipitation  occurred  there  also. 

Solar  light  also  effects  the  decomposition  of  the  nitrite- 
of-amyl  vapor.  On  October  10,  1868, 1  partially  darkened  a 
small  room  in  the  Royal  Institution,  into  which  the  sun 
shone,  permitting  the  light  to  enter  through  an  open  portion 
of  the  window-shutter.  In  the  track  of  the  beam  was 
placed  a  large  plano-convex  lens,  which  formed  a  fine  con- 
vergent cone  in  the  dust  of  the  room  behind  it.  The  ex- 
perimental tube  was  filled  in  the  laboratory,  covered  with  a 
black  cloth,  and  carried  into  the  partially  darkened  room. 
On  thrusting  one  end  of  the  tube  into  the  cone  of  rays  be- 
hind the  lens,  precipitation  within  the  cone  was  copious 
and  immediate.  The  vapor  at  the  distant  end  of  the  tube 
was  in  part  shielded  by  that  in  front,  and  was  also  more 
feebly  acted  on  through  the  divergence  of  the  rays.  On 
reversing  the  tube,  a  second  and  similar  cone  was  precipi- 
tated. 

Physical  Considerations. 

I  sought  to  determine  the  particular  portion  of  the  light 
which  produced  the  foregoing  effects.  When,  previous  to 
entering  the  experimental  tube,  the  beam  was  caused  to 
pass  through  a  red  glass,  the  effect  was  greatly  weakened, 
but  not  extinguished.  This  was  also  the  case  with  various 
samples  of  yellow  glass.  A  blue  glass  being  introduced 
before  the  removal  of  the  yellow  or  the  red,  on  taking  the 
latter  away  prompt  precipitation  occurred  along  the  track 
of  the  blue  beam.  Hence,  in  this  case,  the  more  refrangible 
rays  are  the  most  chemically  active.  The  color  of  the 
liquid  nitrite  of  amyl  indicates  that  this  must  be  the  case; 
it  is  a  feeble  but  distinct  yellow:  in  other  words,  the  yellow 
portion  of  the  beam  is  most  freely  transmitted.  It  is  not, 
however,  the  transmitted  portion  of  any  beam  which 
produces  chemical  action,  but  the  absorbed  portion.  Blue, 
as  the  complementary  color  to  yellow,  is  here  absorbed,  and 
hence  the  more  energetic  action  of  the  blue  rays. 

This  reasoning,  however,  assumes  that  the  same  rays  are 
absorbed  by  the  liquid  and  its  vapor.  The  assumption  is 


NEW  CHEMICAL  REACTIONS.  7? 

worth  testing.  A  solution  of  the  yellow  chromate  of  potash, 
the  color  of  which  may  be  made  almost,  if  not  altogether, 
identical  with  that  of  the  liquid  nitrite  of  arnyl,  was  found 
far  more  effective  in  stopping  the  chemical  rays  than 
either  the  red  or  the  yellow  glass.  But  of  all  substances 
the  liquid  nitrite  itself  is  most  potent  in  arresting  the  rays 
which  act  upon  its  vapor.  A  layer  one-eighth  of  an  inch 
in  thickness,  which  scarcely  perceptibly  affected  the  lu- 
minous intensity,  absorbed  the  entire  chemical  energy  of 
the  concentrated  beam  of  the  electric  light. 

The  close  relation  subsisting  between  a  liquid  and  its 
vapor,  as  regards  their  action  upon  radiant  heat,  has  been 
already  amply  demonstrated.*  As  regards  the  nitrite  of 
amyl,  this  relation  is  more  specific  than  in  the  cases  hith- 
erto adduced;  for  here  the  special  constituent  of  the  beam, 
which  provokes  the  decomposition  of  the  vapor,  is  shown 
to  be  arrested  by  the  liquid. 

A  question  of  extreme  importance  in  molecular  physics 
here  arises:  What  is  the  real  mechanism  of  this  absorption, 
and  where  is  its  seat?f  I  figure,  as  others  do,  a  molecule 
as  a  group  of  atoms,  held  together  by  their  mutual  forces, 
but  still  capable  of  motion  among  themselves.  The  va- 
por of  the  nitrite  of  amyl  is  to  be  regarded  as  an  assem- 
blage of  such  molecules.  The  question  now  before  us  is 
this:  In  the  act  of  absorption,  is  it  the  molecules  that  are 
effective,  or  is  it  their  constituent  atoms?  Is  the  vis  viva 
of  the  intercepted  light-waves  transferred  to  the  molecule 
as  a  whole,  or  to  its  constituent  parts? 

The  molecule,  as  a  whole,  can  only  vibrate  in  virtue  of 
the  forces  exerted  between  it  and  its  neighbor  molecules. 
The  intensity  of  these  forces,  and  consequently  the  rate  of 
vibration,  would,  in  this  case,  be  a  function  of  the  distance 
between  the  molecules.  Now  the  identical  absorption  of  the 
liquid  and  of  the  vaporous  nitrite  of  amyl  indicates  an 
identical  vibrating  period  on  the  part  of  liquid  and  vapor, 
and  this,  to  my  mind,  amounts  to  an  experimental  proof 
that  the  absorption  occurs  in  the  main  within  the  molecule. 
For  it  can  hardly  be  supposed,  if  the  absorption  were  the 

*  "  Phil.  Trans."  1864  ;  "Heat,  a  Mode  of  Motion,"  cLap.  xii.;  and 
p.  45  of  this  volume. 

f  My  attention  was  very  forcibly  directed  to  this  subject  some  years 
ago  by  a  conversation,  with  my  excellent  friend  Professor,  Cla,usiua, 


78  FRAGMENTS  OF  SCIENCE. 

act  of  the  molecule  as  a  whole,  that  it  could  continue  to 
affect  waves  of  the  same  period  after  the  substance  had 
passed  from  the  vaporous  to  the  liquid  state. 

In  point  of  fact,  the  decomposition  of  the  nitrite  of  amyl 
is  itself  to  some  extent  an  illustration  of  this  internal 
molecular  absorption;  for  were  the  absorption  the  act  of 
the  molecule  as  a  whole,  the  relative  motions  of  its  con- 
stituent atoms  would  remain  unchanged,  and  there  would 
be  no  mechanical  cause  for  their  separation.  It  is  probably 
the  synchronism  of  the  vibrations  of  one  portion  of  the 
molecule  with  the  incident  waves,  that  enables  the  ampli- 
tude of  those  vibrations  to  augment,  until  the  chain 
which  binds  the  parts  of  the  molecule  together  is  snapped 
asunder. 

I  anticipate  wide,  if  not  entire,  generality  for  the  fact 
that  a  liquid  and  its  vapor  absorb  the  same  rays.  A  cell 
of  liquid  chlorine  would,  I  imagine,  deprive  light  more  ef- 
fectually of  its  power  of  causing  chlorine  and  hydrogen  to 
combine  than  any  other  filter  of  the  luminous  rays.  The 
rays  which  give  chlorine  its  color  have  nothing  to  do  with 
this  combination,  those  that  are  absorbed  by  the  chlorine 
being  the  really  effective  rays.  A  highly  sensitive  bulb, 
containing  chlorine  and  hydrogen,  in  the  exact  proportions 
necessary  for  the  formation  of  hydrochloric  acid,  was 
placed  at  one  end  of  an  experimental  tube,  the  beam  of  the 
electric  lamp  being  sent  through  it  from  the  other.  The 
bulb  did  not  explode  when  the  tube  was  filled  with  chlorine, 
while  the  explosion  was  violent  and  immediate  when  the 
tube  was  filled  with  air.  I  anticipate  for  the  liquid  chlo- 
rine an  action  similar  to,  but  still  more  energetic  than  that 
exhibited  by  the  gas.  If  this  should  prove  to  be  the  case, 
it  will  favor  the  view  that  chlorine  itself  is  molecular,  and 
not  monatomic. 

Production  of  Sky-blue  by  the  Decomposition  of  Nitrite 
of  Amyl. 

"When  the  quantity  of  nitrite  vapor  is  considerable,  and 
the  light  intense,  the  chemical  action  is  exceedingly  rapid, 
the  particles  precipitated  being  so  large  as  to  whiten  the  lu- 
minous beam.  Not  so,  however,  when  a  well-mixed  and 
highly  attenuated  vapor  fills  the  experimental  tube.  The 
effect  now  to  be  described  was  first  obtained  when  the 


NEW  CHEMICAL  REACTIONS.  79 

vapor  of  the  nitrite  was  derived  from  a  portion  of  its  liquid 
which  had  been  accidentally  introduced  into  the  passage 
through  which  the  dry  air  flowed  into  the  experimental  tube. 

In  this  case,  the  electric  beam  traversed  the  tube  for 
several  seconds  before  any  action  was  visible.  Decomposi- 
tion then  visibly  commenced,  and  advanced  slowly.  When 
the  light  was  very  strong,  the  cloud  appeared  of  a  milky 
blue.  When,  on  the  contrary,  the  intensity  was  moderate, 
the  blue  was  pure  and  deep.  In  Briicke's  important  ex- 
periments on  the  blue  of  the  sky  and  the  morning  and 
evening  red,  pure  mastic  is  dissolved  in  alcohol,  and  then 
dropped  into  water  well  stirred.  When  the  proportion  of 
mastic  to  alcohol  is  correct,  the  resin  is  precipitated  so 
finely  as  to  elude  the  highest  microscopic  power.  By  re- 
flected light,  such  a  medium  appears  bluish,  by  transmitted 
light  yellowish,  which  latter  color,  by  augmenting  the 
quantity  of  the  precipitate,  can  be  caused  to  pass  into 
orange  or  red. 

But  the  development  of  color  in  the  attenuated  nitrite- 
of-amyl  vapor  is  doubtless  more  similar  to  what  takes  place 
in  our  atmosphere.  The  blue,  moreover,  is  far  purer  and 
more  sky-like  than  that  obtained  from  Briicke's  turbid 
medium.  Never,  even  in  the  skies  of  the  Alps,  have  I 
seen  a  richer  or  a  purer  blue  than  that  attainable  by  a  suit- 
able disposition  of  the  light  falling  upon  the  precipitated 
vapor. 

Iodide  of  Allyl. — Among  the  liquids  hitherto  subjected 
to  the  concentrated  electric  light,  iodide  of  allyl,  in  point 
of  rapidity  and  intensity  of  action,  comes  next  to  the 
nitrite  of  arnyl.  With  the  iodide  I  have  employed  both 
oxygen  and  hydrogen,  as  well  as  air,  as  a  vehicle,  and  found 
the  effect  in  all  cases  substantially  the  same.  The  cloud- 
column  here  was  exquisitely  beautiful.  It  revolved  round 
the  axis  of  the  decomposing  beam;  it  was  nipped  at  certain 
places  like  an  hour-glass,  and  round  the  two  bells  of  the 
glass  delicate  cloud-filaments  twisted  themselves  in  spirals. 
It  also  folded  itself  into  convolutions  resembling  those  of 
shells.  In  certain  conditions  of  the  atmosphere  in  the  Alps 
I  have  often  observed  clouds  of  a  special  pearly  luster, 
when  hydrogen  was  made  the  vehicle  of  the  iodide-of-allyl 
vapor  a  similar  luster  was  most  exquisitely  shown.  With 
a  suitable  disposition  of  the  light,  the  purple  hue  of  iodine- 
vapor  came  out  very  strongly  in  the  tube, 


gO  FRAGMENTS  OF  SCIENCE. 

The  remark  already  made,  as  to  the  bearing  of  the 
decomposition  of  nitrite  of  amyl  by  light  on  the  question 
of  molecular  absorption,  applies  here  also;  for  were  the 
absorption  the  work  of  the  molecule  as  a  whole,  the  iodine 
would  not  be  dislodged  from  the  allyl  with  which  it  is 
combined.  The  non-synchronism  of  iodine  with  the 
waves  of  obscure  heat  is  illustrated  by  its  marvelous  trans- 
parency to  such  heat.  May  not  its  synchronism  with  the 
waves  of  light  in  the  present  instance  be  the  cause  of  its 
divorce  from  the  allyl? 

Iodide  of  Isopropyl. — The  action  of  light  upon  the  vapor 
of  this  liquid  is,  at  first,  more  languid  than  upon  iodide  of 
allyl;  indeed  many  beautiful  reactions  may  be  overlooked, 
in  consequence  of  this  languor  at  the  commencement. 
After  some  minutes'  exposure,  however,  clouds  begin  to 
form,  which  grow  in  density  and  in  beauty  as  the  light 
continues  to  act.  In  every  experiment  hitherto  made 
with  this  substance  the  column  of  cloud  filling  the  experi- 
mental tube  was  divided  into  two  distinct  parts  near  the 
middle  of  the  tube.  In  one  experiment  a  globe  of  cloud 
formed  at  the  center,  from  which,  right  and  left,  issued 
an  axis  uniting  the  globe  with  two  adjacent  cylinders. 
Both  globe  and  cylinders  were  animated  by  a  common 
motion  of  rotation.  As  the  action  continued,  paroxysms 
of  motion  were  manifested;  the  various  parts  of  the  cloud 
would  rush  through  each  other  with  sudden  violence. 
During  these  motions  beautiful  and  grotesque  cloud-forms 
were  developed.  At  some  places  the  nebulous  mass  would 
become  ribbed  so  as  to  resemble  the  graining  of  wood;  a 
longitudinal  motion  would  at  times  generate  in  it  a  series 
of  curved  transverse  bands,  the  retarding  influence  of  the 
sides  of  the  tube  causing  an  appearance  resembling,  on  a 
small  scale,  the  dirt-bands  of  the  Mer  de  Glace.  In  the 
anterior  portion  of  the  tube  those  sudden  commotions 
were  most  intense;  here  buds  of  cloud  would  sprout  forth, 
and  grow  in  a  few  seconds  into  perfect  flower-like  forms. 
The  cloud  of  iodide  of  isopropyl  had  a  character  of  its  own, 
and  differed  materially  from  all  others  that  I  had  seen.  A 
gorgeous  mauve  color  was  observed  in  the  last  twelve  inches 
of  the  tube;  the  vapor  of  iodine  was  present  and  it  may 
have  been  the  sky-blue  scattered  by  the  precipitated  par- 
ticles which,  mingling  with  the  purple  of  the  iodine,  pro- 
duced the  mauve.  As  in  all  other  Quses  here  adduced,  the 


NEW  CHEMICAL  ftE ACTIONS.  81 

effects  were  proved  to  be  due  to  the  light;  they  never 
occurred  in  darkness. 

The  forms  assumed  by  some  of  those  actinic  clouds,  as  I 
propose  to  call  them,  in  consequence  of  rotations  and  other 
motions,  due  to  differences  of  temperature,  are  perfectly 
astounding.  I  content  myself  here  with  a  meager  de- 
scription of  one  more  of  them. 

The  tube  being  filled  with  the  sensitive  mixture,  the 
beam  was  sent  through  it,  the  lens  at  the  same  time  being 
so  placed  as  to  produce  a  cone  of  very  intense  light.  Two 
minutes  elapsed  before  anything  was  visible;  but  at  the  end 
of  this  time  a  faint  bluish  cloud  appeared  to  hang  itself  on 
the  most  concentrated  portion  of  the  beam. 

Soon  afterward  a  second  cloud  was  formed  five  inches 
farther  down  the  experimental  tube.  Both  clouds  were 
united  by  a  slender  cord  of  the  same  bluish  tint  as  them- 
selves. 

As  the  action  of  the  light  continued,  the  first  cloud 
gradually  resolved  itself  into  a  series  of  parallel  disks  of 
exquisite  delicacy,  which  rotated  round  an  axis  perpen- 
dicular to  their  surfaces,  and  finally  blended  to  a  screw 
surface  with  an  inclined  generatrix.  This  gradually 
changed  into  a  filmy  funnel,  from  the  narrow  end  of 
which  the  'cord"  extended  to  the  cloud  in  advance.  The 
latter  also  underwent  slow  but  incessant  modification.  It 
first  resolved  itself  into  a  series  of  strata  resembling  those 
of  the  electric  discharge.  After  a  little  time,  and  through 
changes  which  it  was  difficult  to  follow,  both  clouds  pre- 
sented the  appearance  of  a  series  of  concentric  funnels  set 
one  within  the  other,  the  interior  ones  being  seen  through 
the  outer  ones.  Those  of  the  distant  cloud  resembled 
claret-glasses  in  shape.  As  many  as  six  funnels  were  thus 
concentrically  set  together,  the  two  series  being  united  by 
the  delicate  cord  of  cloud  already  referred  to.  Other  cords 
and  slender  tubes  were  afterward  formed,  which  coiled 
themselves  in  delicate  spirals  around  the  funnels. 

Kendering  the  light  along  the  connecting-cord  more 
intense,  it  diminished  in  thickness  and  became  whiter; 
this  was  a  consequence  of  the  enlargement  of  its  particles. 
The  cord  finally  disappeared,  while  the  funnels  melted 
into  two  ghost-like  films,  shaped  like  parasols.  They 
were  barely  visible,  being  of  an  exceedingly  delicate  blue 
tint.  They  seemed  woven  of  blue  air.  To  compare  them 


a*  FRAGMENTS  OF  SCIENCE. 

C/v 

with  cobweb  or  with  gauze  would  be  to  liken  them  ta 
something  infinitely  grosser  than  themselves. 

In  all  cases  a  distant  candle-flame,  when  looked  at 
through  the  cloud,  was  sensibly  undimmed. 

2.  OK   THE   BLUE   COLOR   OF   THE   SKY,    AND  THE    POLAR- 
IZATION  OF   SKYLIGHT.* 
1869. 

After  the  communication  to  the  Royal  Society  of  the 
foregoing  brief  account  of  a  new  Series  of  Chemical 
Reactions  produced  by  Light,  the  experiments  upon  this 
subject  were  continued,  the  number  of  substances  thus 
acted  on  being  considerably  increased. 

I  now,  however,  beg  to  direct  attention  to  two  questions 
glanced  at  incidentally  in  the  preceding  pages— the  blue 
color  of  the  sky,  and  the  polarization  of  skylight.  Reserv- 
ing the  historic  treatment  of  the  subject  fora  more  fitting 
occasion,  I  would  merely  mention  now  that  these  questions 
constitute,  in  the  opinion  of  our  most  eminent  authorities, 
the  two  great  standing  enigmas  of  meteorology.  Indeed  it 
was  the  interest  manifested  in  them  by  Sir  John  Herschel, 
in  a  letter  of  singular  speculative  power,  addressed  to  my- 
self, that  caused  me  to  enter  upon  the  consideration  of 
these  questions  so  soon. 

The  apparatus  with  which  I  work  consists,  as  already 
stated,  of  a  glass  tube  about  a  yard  in  length,  and  from 
%$  to  3  inches  internal  diameter.  The  vapor  to  be  ex- 
amined is  introduced  into  this  tube  in  the  manner  already 
described,  and  upon  it  the  condensed  beam  of  the  electric 
lamp  is  permitted  to  act,  until  the  neutrality  or  the  activity 
of  the  substance  has  been  declared. 

It  has  hitherto  been  my  aim  to  render  the  chemical 
action  of  light  upon  vapors  visible.  For  this  purpose  sub- 
stances have  been  chosen,  one  at  least  of  whose  products  of 
decomposition  under  light  shall  have  a  boiling  point  so 
high,  that  as  soon  as  the  substance  is  formed  it  shall  be 
precipitated.  By  graduating  the  quantity  of  the  vapor, 
this  precipitation  may  be  rendered  of  any  degree  of  fine- 

*  In  my  "  Lectures  on  Light"  (Longmans),  the  polarization  of  light 
will  be  found  briefly,  but,  1  trust,  clearly  explained. 


NEW  CHEMICAL  REACTIONS.  S3 

ness,  forming  particles  distinguishable  by  the  naked  eye, 
or  far  beyond  the  reach  of  our  highest  microscopic  powers. 
I  have  no  reason  to  doubt  that  particles  may  be  thus 
obtained,  whose  diameters  constitute  but  a  small  fraction 
of  the  length  of  a  wave  of  violet  light. 

In  all  cases  when  the  vapors  of  the  liquids  employed  are 
sufficiently  attenuated,  no  matter  what  the  liquid  may  be, 
the  visible  action  commences  with  the  formation  of  a"  blue 
cloud.  But  here  I  must  guard  myself  against  all  miscon- 
ception as  to  the  use  of  this  term.  The  "  cloud  "  here 
referred  to  is  totally  invisible  in  ordinary  daylight.  To 
be  seen,  it  requires  to  be  surrounded  by  darkness,  it  only 
being  illuminated  by  a  powerful  beam  of  light.  This  blue 
cloud  differs  in  many  important  particulars  from  the  finest 
ordinary  clouds,  and  might  justly  have  assigned  to  it  an 
intermediate  position  between  such  clouds  and  true  vapor. 
With  this  explanation,  the  term  "cloud,"  or  "incipient 
cloud/' or  "actinic cloud,"  as  I  propose  to  employ  it,  can- 
not, I  think,  be  misunderstood. 

I  had  been  endeavoring  to  decompose  carbonic  acid  gas 
by  light.  A  faint  bluish  cloud,  due  it  may  be,  or  it  may 
not  be,  to  the  residue  of  some  vapor  previously  employed, 
was  formed  in  the  experimental  tube.  On  looking  across 
this  cloud  through  a  NicoFs  prism,  the  line  of  vision  being 
horizontal,  it  was  found  that  when  the  short  diagonal  of 
the  prism  was  vertical,  the  quantity  of  light  reaching  the 
eye  was  greater  than  when  the  long  diagonal  was  vertical. 
When  a  plate  of  tourmaline  was  held  between  the  eye  and 
the  bluish  cloud,  the  quantity  of  light  reaching  the  eye 
when  the  axis  of  the  prism  was  perpendicular  to  the  axis 
of  the  illuminating  beam,  was  greater  than  when  the 
axis  of  the  crystal  and  of  the  beam  were  parallel  to  each 
other. 

This  was  the  result  all  round  the  experimental  tube. 
Causing  the  crystal  of  .tourmaline  to  revolve  round  the  tube, 
with  its  axis  perpendicular  to  the  illuminating  beam,  the 
quantity  of  light  that  reached  the  eye  was  in  all  its  positions 
a  maximum.  AVheu  the  crystallographic  axis  was  parallel 
to  the  axis  of  the  beam,  the  quantity  of  light  transmitted 
by  the  crystal  was  a  minimum.  From  the  illuminated 
bluish  cloud,  therefore,  polarized  light  was  discharged,  the 
direction  of  maximum  polarization  being  at  right  angles  to 


84  FRAGMENTS  oP  SCIENCE. 

the  illuminating  beam;  the  plane  of  vibration  of  the 
polarized  light  was  perpendicular  to  the  beam.* 

Thin  plates  of  selenite  or  of  quartz,  placed  between  the 
Nicol  and  the  actinic  cloud,  displayed  the  colors  of  polar- 
ized light,  these  colors  being  most  vivid  when  the  line  of 
vision  was  at  right  angles  to  the  experimental  tube.  The 
plate  of  selenite  usually  employed  was  a  circle,  thinnest  at 
the  center,  and  augmenting  uniformly  in  thickness  from 
the  center  outward.  When  placed  in  its  proper  position 
between  the  Nicol  and  the  cloud,  it  exhibited  a  system  of 
splendidly  colored  rings. 

The  cloud  here  referred  to  was  the  first  operated  upon  in 
the  manner  described.  It  may,  however,  be  greatly  im- 
proved upon  by  the  choice  of  proper  substances,  and  by  the 
application,  in  proper  quantities,  of  the  substances  chosen. 
Benzol,  bisulphide  of  carbon,  nitrite  of  amyl,  nitrite  of 
butyl,  iodide  of  allyl,  iodide  of  isopropyl,  and  many  other 
substances  may  be  employed.  I  will  take  the  nitrite  of 
butyl  as  illustrative  of  the  means  adopted  to  secure  the 
best  result,  with  reference  to  the  present  question. 

And  here  it  may  be  mentioned  that  a  vapor,  which  when 
alone,  or  mixed  with  air  in  the  experimental  tube,  re- 
sists the  action  of  light,  or  shows  but  a  feeble  result  of  this 
action,  may,  when  placed  in  proximity  with  another  gas  or 
vapor,  exhibit  vigorous,  if  not  violent  action.  The  case  is 
similar  to  that  of  carbonic  acid  gas,  which,  diffused  in  the 
atmosphere,  resists  the  decomposing  action  of  solar  light, 
but  when  placed  in  contiguity  with  chlorophyll  in  the 
leaves  of  plants,  has  its  molecules  shaken  asunder. 

Dry  air  was  permitted  to  bubble  through  the  liquid  nitrite 
of  butyl,  until  the  experimental  tube,  which  had  been 
previously  exhausted,  was  filled  with  the  mixed  air  and 
vapor.  The  visible  action  of  light  upon  the  mixture  after 
fifteen  minutes'  exposure  was  slight.  The  tube  was  after- 
ward filled  with  half  an  atmosphere  of  the  mixed  air  and 
vapor,  and  a  second  half-atmosphere  of  air  which  had  been 
permitted  to  bubble  through  fresh  commercial  hydrochloric 
acid.  On  sending  the  beam  through  this  mixture,  the  tube, 

*  This  is  still  an  undecided  point;  but  tlie  probabilities  are  so  much 
in  its  favor,  and  it  is  in  my  opinion  so  much  preferable  to  have  a 
physical  image  on  which  the  mind  can  rest,  that  I  do  not  hesitate  to 
employ  the  phraseology  in  the  text. 


NEW  CHEMICAL  REACTIONS.  85 

for  a  moment,  was  optically  empty.  But  the  pause 
amounted  only  to  a  small  fraction  of  a  second,  a  dense 
cloud  being  immediately  precipitated  upon  the  beam. 

This  cloud  began  blue,  but  the  advance  to  whiteness 
was  so  rapid  as  almost  to  justify  the  application  of  the  term 
instantaneous.  The  dense  cloud,  looked  at  perpendicularly 
to  its  axis,  showed  scarcely  any  signs  of  polarization. 
Looked  at  obliquely  the  polarization  was  strong. 

The  experimental  tube  being  again  cleansed  and  ex- 
hausted, the  mixed  air  and  uitrite-of-butyl  vapor  was  per- 
mitted to  enter  it  until  the  associated  mercury  column  was 
depressed  one-tenth  of  an  inch.  In  other  words,  the  air 
and  vapor,  united,  exercised  a  pressure  not  exceeding  one 
three  hundredth  of  an  atmosphere.  Air,  passed  through  a 
solution  of  hydrochloric  acid,  was  then  added,  till  the 
mercury  column  was  depressed  three  inches.  The  con- 
densed beam  of  the  electric  light  was  passed  for  some  time 
through  this  mixture  without  revealing  anything  within 
the  tube  competent  to  scatter  the  light.  Soon,  however, 
a  superbly  blue  cloud  was  formed  along  the  track  of  the 
beam,  and  it  continued  blue  sufficiently  long  to  permit  of 
its  thorough  examination.  The  light  discharged  from  the 
cloud,  at  right  angles  to  its  own  length,  was  at  first  per- 
fectly polarized.  It  could  be  totally  quenched  by  the 
Nicol.  By  degrees  the  cloud  became  of  whitish  blue,  and 
for  a  time  the  selenite  colors,  obtained  by  looking  at  it 
normally,  were  exceedingly  brilliant.  The  direction  of 
maximum  polarization  was  distinctly  at  right  angles  to  the 
illuminating  beam.  This  continued  to  be  the  case  as  long 
as  the  cloud  maintained  a  decided  blue  color,  and  even  for 
some  time  after  the  blue  had  changed  to  whitish  blue. 
But,  as  the  light  continued  to  act,  the  cloud  became  coarser 
and  whiter,  particularly  at  its  center,  where  it  at  length 
ceased  to  discharge  polarized  light  in  the  direction  of  the 
perpendicular,  while  it  continued  to  do  so  at  both  ends. 

But  the  cloud  which  had  thus  ceased  to  polarize  the 
light  emitted  normally,  showed  vivid  selenite  colors  when 
looked  at  obliquely,  proving  that  the  direction  of  maximum 
polarization  changed  with  the  texture  of  the  cloud.  This 
point  shall  receive  further  illustration  subsequently. 

A  blue,  equally  rich  and  more  durable,  was  obtained  by 
employing  the  nitrite-of-butyl  vapor  in  a  still  more  atten- 
uated condition,  £he  instance  here  cited  is  representative, 


86  FRAGMENTS  OF  SCIENCE. 

In  all  cases,  and  with  all  substances,  the  cloud  formed  at 
the  commencement,  when  the  precipitated  particles  are 
sufficiently  fine,  is  Hue,  and  it  can  be  made  to  display  a 
color  rivaling  that  of  the  purest  Italian  sky.  In  all  cases, 
moreover,  this  fine  blue  cloud  polarizes  perfectly  the  beam 
which  illuminates  it,  the  direction  of  polarization  enclosing 
an  angle  of  90  degrees  with  the  axis  of  the  illuminating 
beam. 

It  is  exceedingly  interesting  to  observe  both  the  perfection 
and  the  decay  of  this  polarization.  For  ten  or  fifteen 
minutes  afte/its  first  appearance  the  light  from  a  vividly 
illuminated  actinic  cloud,  looked  at  perpendicularly,  is 
absolutely  quenched  by  a  Nicolas  prism  with  its  longer 
diagonal  vertical.  But  as  the  sky-blue  is  gradually 
rendered  impure  by  the  growth  of  the  particles — in  other 
words,  as  real  clouds  begin  to  be  formed — the  polarization 
begins  to  decay,  a  portion  of  the  light  passing  through  the 
prism  in  all  its  positions.  It  is  worthy  of  note,  that  for 
some  time  after  the  cessation  of  perfect  polarization,  the 
residual  light  which  passes,  when  the  Nicol  is  in  its  position 
of  minimum  transmission,  is  of  a  gorgeous  blue,  the  whiter 
light  of  the  cloud  being  extinguished.*  When  the  cloud 
texture  has  become  sufficiently  coarse  to  approximate  to 
that  of  ordinary  clouds,  the  rotation  of  the  Nicol  ceases  to 
have  any  sensible  effect  on  the  quantity  of  light  discharged 
normally. 

The  perfection  of  the  polarization,  in  a  direction  per- 
pendicular to  the  illuminating  beam,  is  also  illustrated  by 
the  following  experiment:  A  Nicol's  prism,  large  enough 
to  embrace  the  entire  beam  of  the  electric  lamp,  was 
placed  between  the  lamp  and  the  experimental  tube.  A 
few  bubbles  of  air,  carried  through  the  liquid  nitrite  of 
butyl  were  introduced  into  the  tube  and  they  were  followed 
by  about  three  inches  (measured  by  the  mercurial  gauge) 
of  air  which  had  passed  through  aqueous  hydrochloric 
acid.  Sending  the  polarized  beam  through  the  tube,  I 
placed  myself  in  front  of  it,  my  eye  being  on  a  level  with 
its  axis,  my  assistant  occupying  a  similar  position  behind 
the  tube.  The  short  diagonal  of  the  large  Nicol  was  in 
the  first  instance  vertical,  the  plane  of  vibration  of  the 

*  This  shows  that  particles  too  large  to  polarize  the  blue,  polarize 
perfectly  light  of  lower  refrangibilit}-. 


NEW  CHEMICAL  REACTIONS.  87 

emergent  beam  being  therefore  also  vertical.  As  the  light 
continued  to  act,  a  superb  blue  cloud,  visible  to  both  my 
assistant  and  myself,  was  slowly  formed.  But  this  cloud, 
so  deep  and  rich  when  looked  at  from  the  positions  men- 
tioned, utterly  disappeared  when  looked  at  vertically  down- 
ward or  vertically  upward.  Reflection  from  the  cloud 
was  not  possible  in  these  directions.  When  the  large 
Nicol  was  slowly  turned  round  its  axis,  the  eye  of  the 
observer  being  on  the  level  of  the  beam,  and  the  line  of 
vision  perpendicular  to  it,  entire  extinction  of  the  light 
emitted  horizontally  occurred  when  the  longer  diagonal  of 
the  large  Nicol  was  vertical.  But  now  a  vivid  blue  cloud 
was  seen  when  looked  at  downward  or  upward.  This 
truly  fine  experiment,  which  I  contemplated  making  on  my 
own  account,  was  first  definitely  suggested  by  a  remark  in 
a  letter  addressed  to  me  by  Professor  Stokes. 

As  regards  the  polarization  of  skylight,  the  greatest 
stumbling-block  has  hitherto  been,  that,  in  accordance 
with  the  law  of  Brewster,  which  makes  the  index  of 
refraction  the  tangent  of  the  polarizing  angle,  the  reflec- 
tion which  produces  perfect  polarization  would  require  to 
be  made  in  air  upon  air;  and  indeed  this  led  many  of  our 
most  eminent  men,  Brewster  himself  among  the  number, 
to  entertain  the  idea  of  aerial  molecular  reflection.*  I 
have,  however,  operated  upon  substances  of  widely  differ- 

*"  The  cause  of  the  polarization  is  evidently  a  reflection  of  the 
sun's  light  upon  something.  The  question  is  on  what?  Were  the 
angle  of  maximum  polarization  76°,  we  should  look  to  water  or  ice 
as  the  reflecting  body,  however  inconceivable  the  existence  in  a 
cloudless  atmosphere  and  a  hot  summer's  day  of  unevaporated  mole- 
cules (particles?)  of  water.  But  though  we  were  once  of  this  opinion, 
careful  observation  has  satisfied  us  that  90°,  or  thereabouts,  is  the 
correct  angle,  and  that  therefore  whatever  be  the  body  on  which  the 
light  has  been  reflected,  if  polarized  by  a  single  reflection,  the  polar- 
izing angle  must  be  45°,  and  the  index  of  refraction,  which  is  the 
tangent  of  that  angle,  unity;  in  other  words,  the  reflection  would  re- 
quire to  be  made  in  air  upon  air!"  (Sir  John  Herschel,  "  Meteorologv, " 
par.  233.) 

Any  particles,  if  small  enough,  will  produce  both  the  color  and  the 
polarization  of  the  sky.  But  is  the  existence  of  small  water-particles 
on  a  hot  summer's  day  in  the  higher  regions  of  our  atmosphere  incon- 
ceivable? It  is  to  be  remembered  that  the  oxygen  and  nitrogen  of 
the  air  behave  as  a  vacuum  to  radiant  heat,  the  exceedingly  attenuated 
vapor  of  the  higher  atmosphere  being  therefore  in  practical  contact 
with  the  cold  of  space. 


88  FRAGMENTS  OF  SCIENCE. 

ent  refractive  indices,  and  therefore  of  very  different  polar- 
izing angles  as  ordinarily  denned,  but  the  polarization  of 
the  beam,  by  the  incipient  cloud,  has  thus  far  proved  itself 
to  be  absolutely  independent  of  the  polarizing  angle.  The 
law  of  Brewster  does  not  apply  to  matter  in  this  condition, 
and  it  rests  with  the  undulatory  theory  to  explain  why. 
Whenever  the  precipitated  particles  are  sufficiently  fine, 
no  matter  what  the  substance  forming  the  particles  may 
be,  the  direction  of  maximum  polarization  is  at  right 
angles  to  the  illuminating  beam,  the  polarizing  angle  for 
matter  in  this  condition  being  invariably  45  degrees. 

Suppose  our  atmosphere  surrounded  by  an  envelope 
impervious  to  light,  but  with  an  aperture  on  the  sunward 
side  through  which  a  parallel  beam  of  solar  light  could  enter 
and  traverse  the  atmosphere.  Surrounded  by  air  not  directly 
illuminated,  the  track  of  such  a  beam  would  resemble  that 
of  the  parallel  beam  of  the  electric  lamp  through  an  incipient 
cloud.  The  sunbeam  would  be  blue,  and  it  would  dis- 
charge laterally  light  in  precisely  the  same  condition  as 
that  discharged  by  the  incipient  cloud.  In  fact,  azure 
revealed  by  such  a  beam  would  be  "to  all  intents  and 
purposes "  that  which  I  have  called  a  "blue  cloud."  Con- 
versely our  "  blue  cloud"  is,  to  all  intents  and  purposes,  an 
artificial  sky.* 

But,  as  regards  the  polarization  of  the  sky,  we  know 
that  not  only  is  the  direction  of  maximum  polarization  at 
right  angles  to  the  track  of  the  solar  beams,  but  that  at  cer- 
tain angular  distances,  probably  variable  ones,  from  the 
sun,  "  neutral  points/' or  points  of  no  polarization,  exist,  on 
both  sides  of  which  the  planes  of  atmospheric  polarization 
are  at  right  angles  to  each  other.  I  have  made  various 
observations  upon  this  subject  which  are  reserved  for  the 
present;  but,  pending  the  more  complete  examination  of 

*  The  opinion  of  Sir  John  Herschel  connecting  the  polarizations 
and  the  blue  color  of  the  sky,  is  verified  by  the  foregoing  results. 
"  The  more  the  subject  [the  polarization  of  skylight]  is  considered," 
writes  this  eminent  philosopher,  "  the  more  it  will  be  found  beset 
with  difficulties,  and  its  explanation  when  arrived  at  will  probably  be 
found  to  carry  with  it  that  of  the  blue  color  of  the  sky  itself,  and  of 
the  great  quantity  of  light  it  actually  does  send  down  to  us."  "  We 
may  observe,  too,"  he  adds,  "  that  it  is  only  where  the  purity  of  the 
sky  is  most  absolute  that  the  polarization  is  developed  in  its  highest 
degree,  and  that  where  there  is  the  slightest  perceptible  tendency  to 
cirrus  it  is  materially  impaired,"  TU»8  applies  word,  for  word  to 'our 
"incipient  clouds," 


NEW  CHEMICAL  REACTIONS.  89 

the  question,  the  following  facts  bearing  upon  it  may  be 
submitted. 

The  parallel  beam  employed  in  these  experiments 
tracked  its  way  through  the  laboratory  air,  exactly  as  sun- 
beams are  seen  to  do  in  the  dusty  air  of  London.  I  have 
reason  to  believe  that  a  great  portion  of  the  matter  thus 
floating  in  the  laboratory  air  consists  of  organic  particles, 
which  are  capable  of  imparting  a  perceptibly  bluish  tint  to 
the  air.  These  also  showed,  though  far  less  vividly,  all 
the  effects  of  polarization  obtained  with  the  incipient  clouds. 
The  light  discharged  laterally  from  the  track  of  the  illu- 
minating beam  polarized,  though  not  perfectly,  the  direction 
of  maximum  polarization  being  at  right  angles  to  the  beam. 
At  all  points  of  the  beam,  moreover,  throughout  its  entire 
length,  the  light  emitted  normally  was  in  the  same  state  of 
polarization.  Keeping  the  positions  of  the  Nicol  and  the 
selenite  constant,  the  same  colors  were  observed  through- 
out the  entire  beam,  when  the  line  of  vision  was  perpendic- 
ular to  its  length. 

The  horizontal  column  of  air,  thus  illuminated,  was  18 
feet  long,  and  could  therefore  be  looked  at  very  obliquely. 
I  placed  myself  near  the  end  of  the  beam,  as  it  issued  from 
the  electric  lamp,  and,  looking  through  the  Nicol  and 
selenite  more  and  more  obliquely  at  the  beam,  observed 
the  colors  fading  until  they  disappeared.  Augmenting 
the  obliquity  the  colors  appeared  once  more,  but  they  were 
now  complementary  to  the  former  ones. 

Hence  this  beam,  like  the  sky,  exhibited  a  neutral  point, 
on  opposiue  sides  of  which  the  light  was  polarized  in 
planes  at  right  angles  to  each  other. 

Thinking  that  the  action  observed  in  the  laboratory 
might  be  caused,  in  some  way,  by  the  vaporous  fumes 
diffused  in  its  air,  I  had  the  light  removed  to  a  room  at  the 
top  of  the  Royal  Institution.  The  track  of  the  beam  was 
seen  very  finely  in  the  air  of  this  room,  a  length  of  14  or  15 
foet  being  attainable.  This  beam  exhibited  all  the  effects 
observed  with  the  beam  in  the  laboratory.  Even  the  un- 
condensed  electric  light  falling  on  the  floating  matter 
showed,  though  faintly,  the  effects  of  polarization. 

When  the  air  was  so  sifted  as  to  entirely  remove  the  visible 
floating  matter,  it  no  longer  exerted  any  sensible  action  upon 
the  light,  but  behaved  like  a  vacuum.  The  light  is  scattered 
and  polarized  by  particles,  not  by  molecules  or  atoms* 


90  FRAGMENTS  OF  SCIENCE. 

By  operating  upon  the  fumes  of  chloride  of  ammonium, 
the  smoke  of  bro\vu  paper,  and  tobacco-smoke,  I  had  va- 
ried and  confirmed  in  many  ways  those  experiments  on 
neutral  points,  when  my  attention  was  drawn  by  Sir 
Charles  Wheatstoue  to  an  important  observation  communi- 
cated to  the  Paris  Academy  in  1860  by  Professor  Govi,  of 
Turin.*  M.  Govi  had  been  led  to  examine  a  beam  of  light 
sent  through  a  room  in  which  were  successively  diffused 
the  smoke  of  incense,  and  tobacco-smoke.  His  first  brief 
communication  stated  the  fact  of  polarization  by  such 
smoke.;  but  in  his  second  communication  he  announced 
the  discovery  of  a  neutral  point  in  the  beam,  at  the  op- 
posite sides  of  which  the  light  was  polarized  in  planes  at 
right  angles  to  each  other. 

But  unlike  my  observations  on  the  laboratory  air,  and 
unlike  the  action  of  the  sky,  the  direction  of  maximum  polar- 
ization in  M.  Govi's  experiment  enclosed  a  very  small 
angle  with  the  axis  of  the  illuminating  beam.  The  ques- 
tion was  left  in  this  condition,  and  I  am  not  aware  that  M. 
Govi  or  any  other  investigator  has  pursued  it  further. 

I  had  noticed,  as  before  stated,  that  as  the  clouds  formed 
in  the  experimental  tube  became  denser,  the  polarization 
of  the  light  discharged  at  right  angles  to  the  beam  became 
weaker,  the  direction  of  maximum  polarization  becoming 
oblique  to  the  beam.  Experiments  on  the  fumes  of  chlo- 
ride of  ammonium  gave  me  also  reason  to  suspect  that  the 
position  of  the  neutral  point  was  tiot  constant,  but  that  it 
varied  with  the  density  of  the  illuminated  fumes. 

The  examination  of  these  questions  led  to  the  following 
new  and  remarkable  results:  The  laboratory  being  well 
filled  with  the  fumes  of  incense,  and  sufficient  time  being 
allowed  for  their  uniform  diffusion,  the  electric  beam  was  sent 
through  the  smoke.  From  the  track  of  the  beam  polarized 
light  was  discharged;  but  the  direction  of  maximum  polar- 
ization, instead  of  being  perpendicular,  now  enclosed  an 
angle  of  only  12  degrees  or  13  degrees  with  the  axis  of  the 
beam. 

A  neutral  point,  with  complementary  effects  at  opposite 
sides  of  it,  was  also  exhibited  by  the  beam.  The  angle  en- 
closed by  the  axis  of  the  beam,  and  a  line  drawn  from  the 


*  "  Ctomptes  Rend  us,"  tome  li.  pp.  360  and  669, 


NEW  CHEMICAL  REACTIONS.  91 

neutral  point  to  the  observer's  eye  measured  in  the  first 
instance  66  degrees. 

The  windows  of  the  laboratory  were  now  opened  for 
some  minutes,  a  portion  of  the  incense-smoke  being  per- 
mitted to  escape.  On  again  darkening  the  room  and  turn- 
ing on  the  light,  the  line  of  vision  to  the  neutral  point  was 
found  to  enclose,  with  the  axis  of  the  beam,  an  angle  of  63 
degrees. 

The  windows  were  again  opened  for  a  few  minutes,  more 
of  the  smoke  being  permitted  to  escape.  Measured  as  be- 
fore, the  angle  referred  to  was  found  to  be  54  degrees. 

This  process  was  repeated  three  additional  times;  the 
neutral  point  was  found  to  recede  lower  and  lower  down 
the  beam,  the  angle  between  a  line  drawn  from  the  eye  to 
the  neutral  point  and  the  axis  of  the  beam  falling  succes- 
sively from  54  degrees  to  49  degreees,  43  degrees  and  33 
degrees. 

The  distances,roughly  measured,  of  the  neutral  point  from 
the  lamp,  corresponding  to  the  foregoing  series  of  observa- 
tions, were  these: 


1st  observation 

2d 

3d 

4th 

5th 

6th 


2  feet  2  inches. 


At  the  end  of  this  series  of  experiments  the  direction  of 
maximum  polarization  had  again  become  normal  to  the 
beam. 

The  laboratory  was  next  filled  with  the  fumes  of  gun- 
powder. In  five  successive  experiments,  corresponding  to 
five  different  densities  of  the  gunpowder-smoke,  the  angles 
enclosed  between  the  line  of  vision  to  the  neutral  point  and 
the  axis  of  the  beam,  were  63  degrees,  50  degrees,  47  de- 
grees, 42  degrees,  and  38  degrees  respectively. 

After  the  clouds  of  gunpowder  had  cleared  away,  the 
laboratory  was  filled  with  the  fumes  of  common  resin,  ren- 
dered so  dense  as  to  be  very  irritating  to  the  lungs.  The 
direction  of  maximum  polarization  enclosed,  in  this  case, 
an  angle  of  12  degrees,  or  thereabouts,  with  the  axis  of  the 
beam.  Looked  at,  as  in  the  former  instances,  from  a 


92  FRAGMENTS  OF  SCIENCE. 

position  near  the  electric  lamp,  no  neutral  point  was  ob- 
served throughout  the  entire  extent  of  the  beam. 

When,  this  beam  was  looked  at  normally  through  tha 
selenite  and  Nicol,  the  ring-system,  though  not  brilliant,, 
was  distinct.  Keeping  the  eye  upon  the  plate  of  selenite,, 
and  the  line  of  vision  perpendicular,  the  windows  were 
opened,  the  blinds  remaining  undrawn.  The  resinous 
fumes  slowly  diminished,  and  as  they  did  so  the  ring- 
system  became  paler.  It  finally  disappeared.  Continuing 
to  look  in  the  same  direction,  the  rings  revived,  but  now 
the  colors  were  complementary  to  the  former  ones.  Tlie 
neutral  point  had  passed  me  in  its  motion  down  the  beam,, 
consequent  upon  the  attenuation  of  the  fumes  of  resin. 

With  the  fumes  of  chloride  of  ammonium  substantially 
the  same  results  were  obtained.  Sufficient,  however,  has 
been  here  stated  to  illustrate  the  variability  of  the  position 
of  the  neutral  point.* 

By  a  puff  of  tobacco-smoke,  or  of  condensed  steam,  blown 
into  the  illuminated  beam,  the  brilliancy  of  the  selenite 
colors  may  be  greatly  enhanced.  But  with  different  clouds; 
two  different  effects  are  produced.  Let  the  ring-system  ob- 
served in  the  common  air  be  brought  to  its  maximum 
strength,  and  then  let  an  attenuated  cloud  of  chloride  of 
ammonium  be  thrown  into  the  beam  at  the  point  looked  at; 
the  ring  system  flashes  out  with  augmented  brilliancy,  but 
the  character  of  the  polarization  remains  unchanged. 
This  is  also  the  case  when  phosphorus  or  sulphur  is  burned 
underneath  the  beam,  so  as  to  cause  the  fine  particles  of  phos- 
phorus or  of  sulphur  to  rise  into  the  light.  With  the 
sulphur-fumes  the  brilliancy  of  the  colors  is  exceedingly 
intensified;  but  in  none  of  these  cases  is  there  any  change 
in  the  character  of  the  polarization. 

But  when  a  puff  of  the  fumes  of  hydrochloric  acid, 
hydriodic  acid,  or  nitric  acid  is  thrown  into  the  beam, 
there  is  a  complete  reversal  of  the  selenite  tints.  Each  of 
these  clouds  twists  the  plane  of  polarization  90  degrees, 
causing  the  center  of  the  ring-system  to  change  from  black 

*  Brewster  has  proved  the  variability  of  the  position  of  the  neutral 
point  for  skylight  with  the  sun's  altitude,  a  result  pbviQttglv  connoted, 
with  |Ue  foregoing  experiments, 


XEW  CHEMICAL  nEACTIONS.  93 

to  white,  and  the  rings  themselves  to  emit  their  comple- 
mentary colors.* 

Almost  all  liquids  have  motes  in  them  sufficiently 
numerous  to  polarize  sensibly  the  light,  and  very  beautiful 
effects  may  be  obtained  by  simple  artificial  devices.  When, 
for  example,  a  cell  of  distilled  water  is  placed  in  front  of 
the  electric  lamp,  and  a  thin  slice  of  the  beam  is  permitted 
to  pass  through  it,  scarcely  any  polarized  light  is  discharged, 
and  scarcely  any  color  produced  with  a  plate  of  selenite. 
But  if  a  bit  of  soap  be  agitated  in  the  water  above  the  beam, 
the  moment  the  infinitesimal  particles  reach  the  light  the 
liquid  sends  forth  laterally  almost  perfectly  polarized  light; 
and  if  the  selenite  be  employed,  vivid  colors  flash  into  ex- 
istence. A  still  more  brilliant  result  is  obtained  with 
mastic  dissolved  in  a  great  excess  of  alcohol. 

The  selenite  rings,  in  fact,  constitute  an  extremely 
delicate  test  as  to  the  collective  quantity  of  individually  in- 
visible particles  in  a  liquid.  Commencing  with  distilled 
water,  for  example,  a  thick  slice  of  light  is  necessary  to 
make  the  polarization  of  its  suspended  particles  sensible. 
A  much  thinner1  slice  suffices  for  common  water;  while, 
with  Brucke's  precipitated  mastic,  a  slice  too  thin  to 
produce  any  sensible  effect  with  most  other  liquids,  suffices 
to  bring  out  vividly  the  selenite  colors. 

3.    THE   SKY   OF    THE   ALPS. 

The  vision  of  an  object  always  implies  a  differential 
action  on  the  retina  of  the  observer.  The  object  is  dis- 
tinguished from  surrounding  space  by  its  excess  or  defect 
of  light  in  relation  to  that  space.  By  altering  the  illumi- 
nation, either  of  the  object  itself  or  of  its  environment,  we 
alter  the  appearance  of  the  object.  Take  the  case  of  clouds 
floating  in  the  atmosphere  with  patches  of  blue  between 
them.  Anything  that  changes  the  illumination  of  either 
alters  the  appearance  of  both,  that  appearance  depending, 
as  stated,  upon  differential  action.  Now  the  light  of  the 
sky,  being  polarized,  may,  as  the  reader  of  the  foregoing 

*  Sir  John  Herschel  suggested  to  ine  that  this  change  of  the  polar- 
ization from  positive  to  negative  may  indicate  a  change  from  polar- 
ization by  reflection  to  polarization  by  refraction.  This  thought  re- 
peatedly occurred  to  me  while  looking  at  the  effects;  but  it  will 
require  much  following  up  before  it  emerges  into  clearness. 


94  FRAGMENTS  OF  SCIENCE. 

pages  knows,  be  in  great  part  quenched  by  a  Nicol's  prism, 
while  the  light  of  a  common  cloud,  being  unpolarized, 
cannot  be  thus  extinguished.  Hence  the  possibility  of 
very  remarkable  variations,  not  only  in  the  aspect  of  the 
firmament,  which  is  really  changed,  but  also  in  the  aspect 
of  the  clouds,  which  have  that  firmament  as  a  background. 
It  is  possible,  for  example,  to  choose  clouds  of  such  a  depth 
of  shade  that  when  the  Nicol  quenches  the  light  behind 
them,  they  shall  vanish,  being  undistingtiishable  from  the 
residual  dull  tint  which  outlives  the  extinction  of  the 
brilliancy  of  the  sky.  A  cloud  less  deeply  shaded,  but 
still  deep  enough,  when  viewed  with  the  naked  eye,  to 
appear  dark  on  a  bright  ground,  is  suddenly  changed  to  a 
white  cloud  on  a  dark  ground  by  the  quenching  'of  the 
light  behind  it.  When  a  reddish  cloud  at  sunset  chances 
to  float  in  the  region  of  maximum  polarization,  the  quench- 
ing of  the  surrounding  light  causes  it  to  flash  with  a 
brighter  crimson.  Last  Easter  eve  the  Dartmoor  sky, 
which  had  just  been  cleansed  by  a  snow-storm,  wore  a  very 
wild  appearance.  Round  the  horizon  it  was  of  steely 
brilliancy,  while  reddish  cumuli  and  cirri  floated  south- 
ward. When  the  sky  was  quenched  behind  them  these 
floating  masses  seemed  like  dull  embers  suddenly  blown 
upon;  they  brightened  like  a  fire. 

In  the  Alps  we  have  the  most  magnificent  examples  of 
crimson  clouds  and  snows,  so  that  the  effects  just  referred 
to  may  be  here  studied  under  the  best  possible  conditions. 
On  August  23,  1869,  the  evening  Alpenglow  was  very 
fine,  though  it  did  not  reach  its  maximum  depth  and 
splendor.  The  side  of  the  Weisshorn  seen  from  the  Bel 
Alp,  being  turned  from  the  sun,  was  tinted  mauve;  but  I 
wished  to  observe  one  of  the  rose-colored  buttresses  of  the 
mountain.  Such  a  one  was  visible  from  a  point  a  few 
hundred  feet  above  the  hotel.  The  MaUerhorn  also, 
though  for  the  most  part  in  shade,  had  a  crimson  projec- 
tion, while  a  deep  ruddy  red  lingered  along  its  western 
shoulder.  Four  distant  peaks  and  buttresses  of  the  Dom, 
in  addition  to  its  dominant  head — all  covered  with  pure 
snow— were  reddened  by  the  light  of  sunset.  The  shoulder 
of  the  Alphubel  was  similarly  colored,  while  the  great  mass 
of  the  Fletschorn  was  all  aglow,  and  so  was  the  snowy 
spine  of  the  Monte  Leone. 

Looking  at  the  Weisshorn  through  the  Nicol,  the  glow 


NEW  CHEMICAL  REACTIONS.  95 

of  its  protuberance  was  strong  or  weak  according  to  the 
position  of  the  prism.  The  summit  also  underwent 
striking  changes.  In  one  position  of  the  prism  it  exhibited 
a  pale  white  against  a  dark  background;  in  the  rectangular 
position  it  was  a  dark  mauve  against  a  light  background. 
The  red  of  the  Matterhorn  changed  iu  a  similar  manner; 
but  the  whole  mountain  also  passed  through  wonderful 
changes  of  definition.  The  air  at  the  time  was  filled  with 
a  silvery  haze,  in  which  the  Matterhorn  almost  disappeared. 
This  could  be  wholly  quenched  by  the  Nicol,  and  then  the 
mountain  sprang  forth  with  astonishing  solidity  and 
detachment  from  the  surrounding  air.  The  changes  of 
the  Dom  were  still  more  wonderful.  A  vast  amount  of 
light  could  be  removed  from  the  sky  behind  it,  for  it 
occupied  the  position  of  maximum  polarization.  By  a 
little  practice  with  the  Nicol  it  was  easy  to  render  the  ex- 
tinction of  the  light,  or  its  restoration,  almost  instan- 
taneous. When  the  sky  was  quenched,  the  four  minor 
peaks  and  buttresses,  and  the  summit  of  the  Dom,  to- 
gether with  the  shoulder  of  the  Alphubel,  glowed  as  if  set 
suddenly  on  fire.  This  was  immediately  dimmed  by  turn- 
ing the  Nicol  through  an  angle  of  90  degrees.  It  was  not 
the  stoppage  of  the  light  of  the  sky  behind  the  mountains 
alone  which  produced  this  startling  effect;  the  air  between 
them  and  me  was  highly  opalescent,  and  the  quenching  of 
this  intermediate  glare  augmented  remarkably  the  dis- 
tinctness of  the  mountains. 

On  the  morning  of  August  24  similar  effects  were  finely 
shown.  At  10  A.M.  all  three  mountains,  the  Dom,  the 
Matterhorn,  and  the  Weisshorn,were  powerfully  affected 
by  the  Nicol.  But  in  this  instance  also,  the  line  drawn  to 
the  Dorn  being  very  nearly  perpendicular  to  the  solar  beams, 
the  effects  on  this  mountain  were  most  striking.  The 
gray  summit  of  the  Matterhorn,  at  the  same  time,  could 
scarcely  be  distinguished  from  the  opalescent  haze  around 
it;  but  when  the  Nicol  Quenched  the  haze,  the  summit 
became  instantly  isolated,  and  stood  out  in  bold  definition. 
It  is  to  be  remembered  that  in  the  production  of  these 
effects  the  only  things  changed  are  the  sky  behind,  and  the 
luminous  haze  in  front  of  the  mountains;  that  these  are 
changed  because  the  light  emitted  from  the  sky  and  from 
the  haze  is  plane  polarized  light,  and  that  the  light  from 
the  snows  and  from  the  mountains,  being  sensibly  unpolar- 


96  FRAGMENTS  OP  SCtENCtt. 

ized,  is  not  directly  affected  by  the  Nicol.  It  will  also  be 
understood  that  it  is  not  the  interposition  of  the  haze  as  an 
opaque  body  that  renders  the  mountains  indistinct,  but 
that  it  is  the  light  of  the  haze  which  dims  and  bewilders 
the  eye,  and  thus  weakens  the  definition  of  objects  seen 
through  it. 

The  results  have  a  direct  bearing  upon  what  artists  call 
"aerial  perspective/'  As  we  look:  from  the  summit  of  Mont 
Blanc,  or  from  the  lower  elevation,  at  the  serried  crowd  of 
peaks,especially  if  the  mountains  be  darkly  colored — cov- 
ered with  pines,  for  example — every  peak  and  ridge  is 
separated  from  the  mountains  behind  it  by  a  thin  blue  haze 
which  renders  the  relations  of  the  mountains  as  to  distance 
unmistakable.  When  this  haze  is  regarded  through  the 
Nicol  perpendicular  to  the  sun's  rays,  it  is  in  many  cases 
wholly  quenched,  because  the  light  which  it  emits  in  this 
direction  is  wholly  polarized.  When  this  happens,  aerial 
perspective  is  abolished,  and  mountains  very  differently 
distant  appear  to  rise  in  the  same  vertical  plane.  Close  to 
the  Bel  Alp,  for  instance,  is  the  gorge  of  the  Massa,  and 
beyond  the  gorge  is  a  high  ridge  darkened  by  pines.  This 
ridge  may  be  projected  upon  the  dark  slopes  at  the  oppo- 
site side  of  the  Ehone  valley,  and  between  both  we  have 
the  blue  haze  referred  to,  throwing  the  distant  mountains 
far  away.  But  at  certain  hours  of  the  day  the  haze  may  be 
quenched,  and  then  the  Massa  ridge  and  the  mountains  be- 
yond the  Ehone  seem  almost  equally  distant  from  the  eye. 
The  one  appears,  as  it  were,  a  vertical  continuation  of  the 
other.  The  haze  varies  with  the  temperature  and  humidity 
of  the  atmosphere.  At  certain  times  and  places  it  is  almost 
as  blue  as  the  sky  itself;  but  to  see  its  color,  the  attention 
must  be  withdrawn  from  the  mountains  and  from  the  trees 
which  cover  them.  In  point  of  fact,  the  haze  is  a  piece  of 
more  or  less  perfect  sky;  it  is  produced  in  the  same  man- 
ner, and  is  subject  to  the  same  laws,  as  the  firmament 
itself.  We  live  in  the  sky,  not  under  it. 

These  points  were  further  elucidated  by  the  deportment 
of  the  selenite  plate,  with  which  the  readers  of  the  forego- 
ing pages  are  so  well  acquainted.  On  some  of  the  sunny 
days  of  August  the  haze  in  the  valley  of  the  Ehone,  as 
looked  at  from  the  Bel  Alp,  was  very  remarkable.  Toward 
evening  the  sky  above  the  mountains  opposite  to  my  place 
of  observation  yielded  a  series  of  the  most  splendidly  col- 


NEW  CHEMICAL  REACTIONS.  97 

ored  iris-rings;  but  on  lowering  the  selenite  until  it  had 
the  darkness  of  the  pines  at  the  opposite  side  of  the  Rhone 
valley,  instead  of  the  darkness  of  space,  as  a  background, 
the  colors  were  not  much  diminished  in  brilliancy.  I 
should  estimate  the  distance  across  the  valley,  as  the  crow 
flies,  to  the  opposite  mountain,  at  nine  miles;  so  that  a 
body  of  air  of  this  thickness 'can,  under  favorable  circum- 
stances, produce  chromatic  effects  of  polarization  almost  as 
vivid  as  those  produced  by  the  sky  itself. 

Again:  the  light  of  a  .landscape,  as  of  most  other  things, 
consists  of  two  parts;  the  one,  coming  purely  from  superfi- 
cial reflection,  is  always  of  the  same  color  as  the  light  which 
falls  upon  the  landscape;  the  other  part  reaches  us  from  a 
certain  depth  within  the  objects  which  compose  the  land- 
scape, and  it  is  this  portion  of  the  total  light  which  gives 
these  objects  their  distinctive  colors.  The  white  light  of 
the  sun  enters  all  substances  to  a  certain  depth,  and  is 
partly  ejected  by  internal  reflection;  each  distinct  substance 
absorbing  and  reflecting  the  light,  in  accordance  with  the 
laws  of  its  own  molecular  constitution.  Thus  the  solar 
light  is  sifted  by  the  landscape,  which  appears  in  such 
colors  and  variations  of  color  as,  after  the  sifting  process, 
reach  the  observer's  eye.  Thus  the  bright  green  of  grass, 
or  the  darker  color  of  the  pine,  never  comes  to  us  alone, 
but  is  always  mingled  with  an  amount  of  light  derived 
from  superficial  reflection.  A  certain  hard  briliancy  is 
conferred  upon  the  woods  and  meadows  by  this  superfi- 
cially reflected  light.  Under  certain  circumstances,  it  may 
be  quenched  by  a  NicoFs  prism,  and  we  then  obtain  the  true 
color  of  the  grass  and  foliage.  Trees  and  meadows,  thus 
regarded,  exhibit  a  richness  and  softness  of  tint  which  they 
never  show  as  long  as  the  superficial  light  is  permitted  to 
mingle  with  the  true  interior  emission.  The  needles  of 
the  pines  show  this  effect  very  well,  large-leaved  trees  still 
better;  while  a  glimmering  field  of  maize  exhibits  the  most 
extraordinary  variations  when  looked  at  through  the  rotat- 
ing Nicol. 

Thoughts  and  questions  like  those  here  referred  to  took 
me,  in  August,  1869,  to  the  top  of  the  Aletschhorn.  The 
effects  described  in  the  foregoing  paragraphs  were  for  the 
most  part  reproduced  on  the  summit  of  the  mountain.  I 
scanned  the  whole  of  the  sky  with  rny  Nicol.  Both  alone, 
and  in  conjunction  with  the  selenite,  it  pronounced  the 


98  FRAGMENTS  OF  SCIENCE. 

perpendicular  to  the  solar  beams  to  be  the  direction  of 
maximum  polarization.  But  at  no  portion  of  the  firma- 
ment was  the  polarization  complete.  The  artificial  sky 
produced  in  the  experiments  recorded  in  the  preceding 
pages  could,  in  this  respect,  be  rendered  far  more  perfect 
than  the  natural  one;  while  the  gorgeous  "residual  blue" 
which  makes  its  appearance  when  the  polarization  of  the 
artificial  sky  ceases  to  be  perfect,  was  strongly  contrasted 
with  the  lack-luster  hue  which,  in  the  case  of  the  firma- 
ment, outlived  the  extinction  of  the  brilliancy.  With 
certain  substances,  however,  artificially  treated,  this  dull 
residue  may  also  be  obtained. 

All  along  the  arc  from  the  Matterhorn  to  Mont  Blanc 
the  light  of  the  sky  immediately  above  the  mountains  was 
powerfully  acted  upon  by  the  Nicol.  In  some  cases  the 
variations  of  intensity  were  astonishing.  1  have  already 
said  that  a  little  practice  enables  the  observer  to  shift  the 
Nicol  from  one  position  to  another  so  rapidly  as  to  render 
the  alternative  extinction  and  restoration  of  the  light  im- 
mediate. When  this  was  done  along  the  arc  to  which  I 
have  referred,  the  alternations  of  light  and  darkness 
resembled  the  play  of  sheet  lightning  behind  the  moun- 
tains. There  was  an  element  of  awe  connected  with  the 
suddenness  with  which  the  mighty  masses,  ranged  along 
the  line  referred  to,  changed  their  aspect  and  definition 
under  the  operation  of  the  prism. 


[In  the  last  edition  of  the  "  Fragments  of  Science"  an  essay  on 
"  Dust  and  Disease"  followed  here;  but  as  almost  all  my  writings  on 
the  "  Germ  Theory"  are  now  collected  in  a  single  volume  entitled 
"Essays  on  the  Floating  Matter  of  the  Air,"  "  Dust  and  Disease"  no 
longer  appears  in  the  "  Fragments."  In  its  place  I  venture  to  intro- 
duce a  short  article  written  early  last  year  for  an  important  American 
magazine.] 

CHAPTER  V. 

THE   SKY.* 

INVITED  to  write  for  the  Forum  an  article  that 
would  have  brought  me  face  to  face  with  "problems  of 
life  and  mind"  for  which  I  was  at  the  moment  unprepared, 
and  unwilling  to  decline  a  request  so  courteously  made,  I 

*From  1?i6  Forum,  February,  1&J8, 


THE  SKY.  99 

offered,  if  the  editor  cared  to  accept  it,  to  send  him  a  con- 
tribution on  the  subject  here  presented. 

1  mentioned  this  subject,  thinking  that,  in  addition  to 
its  interest  as  a  fragment  of  "  natural  knowledge/'  it 
might  permit  of  a  glance  at  the  workings  of  the  scientific 
mind  when  engaged  on  the  deeper  problems  which  come 
before  it.  In  the  house  of  Science  are  many  mansions, 
occupied  by  tenants  of  diverse  kinds.  Some  of  them 
execute  with  painstaking  fidelity  the  useful  work  of  obser- 
vation, recording  from  day  to  day  the  aspects  of  ^Nature, 
or  the  indications  of  instruments  devised  to  reveal  her 
ways.  Others  there  are  who  add  to  this  capacity  for  obser- 
vation a  power  over  the  language  of  experiment,  by  means 
of  which  they  put  questions  to  Nature,  and  receive  from 
her  intelligible  replies.  There  is,  again,  a  third  class  of 
minds,  that  cannot  rest  content  with  observation  and  ex- 
periment, whose  love  of  causal  unity  tempts  them  perpet- 
ually to  break  through  the  limitations  of  the  senses,  and 
to  seek  beyond  them  the  roots  and  reasons  of  the  phenom- 
ena which  the  observer  and  experimenter  record.  To 
such  spirits — adventurous  and  firm — we  are  indebted  for 
our  deeper  knowledge  of  the  methods  by  which  the  physical 
universe  is  ordered  and  ruled. 

In  his  efforts  to  cross  the  common  bourne  of -the  known 
and  the  unknown,  the  effective  force  of  the  man  of  science 
must  depend,  to  a  great  extent,  upon  his  acquired  knowl- 
edge. But  knowledge  alone  will  not  do;  a  stored  memory 
will  not  suffice;  inspiration  must  lend  its  aid.  Scientific 
inspiration,  however,  is  usually,  if  not  always,  the  fruit  of 
long  reflection — of  patiently  "intending  the  mind,"  as 
Newton  phrased  it;  and  as  Copernicus,  Newton,  and 
Darwin  practiced  it;  until  outer  darkness  yields  a  glimmer, 
which  in  due  time  opens  out  into  perfect  intellectual  day. 
From  some  of  his  expressions  it  might  be  inferred  that 
Newton  scorned  hypotheses;  but  he  allowed  them,  never- 
theless, an  open  avenue  to  his  own  mind.  He  propounded 
the  famous  corpuscular  theory  of  light,  illustrating  it  and 
defending  it  with  a  skill,  power,  and  fascination  which 
subsequently  won  for  it  ardent  supporters  among  the  best 
intellects  of  the  world.  This  theory,  moreover,  was 
weighted  with  a  supplementary  hypothesis,  which  ascribed 
to  the  luminiferous  molecules  "  fits  of  easy  reflection  and 
transmission/'  iu  virtue  of  which  they  were  sometimes 


100  FRAGMENTS  OF  SCIENCE. 

repelled  from  the  surfaces  of  bodies  and  sometimes  per- 
mitted to  pass  through.  Newton  may  have  scorned  the 
levity  with  which  hypotheses  are  sometimes  framed;  but  he 
lived  in  an  atmosphere  of  theory,  which  he,  like  all  pro- 
found scientific  thinkers,  found  to  be  the  very  breath  of 
his  intellectual  life. 

The  theorist  takes  his  conceptions  from  the  world  of 
fact,  and  refines  and  alters  them  to  suit  his  needs.  The 
sensation  of  sound  was  known  to  be  produced  by  aerial 
waves  impinging  on  the  auditory  nerve.  Air  being  a 
thing  that  could  be  felt,  and  its  vibrations,  by  suitable 
treatment,  made  manifest  to  the  eye,  there  was  here  a 
physical  basis  for  the  "scientific  imagination "  to  build 
upon.  Both  Hooke  and  Huyghens  built  upon  it  with 
effect.  By  the  illustrious  astronomer  last  named  the  con- 
ception of  waves  was  definitely  transplanted  from  its  ter- 
restrial birthplace  to  a  universal  medium  whose  undulations 
could  only  be  intellectually  discerned.  Huyghens  did  not 
establish  the  undulatory  theory,  but  he  took  the  first  firm 
step  toward  establishing  it.  Laying  this  theory  at  the  root 
of  the  phenomena  of  light,  he  went  a  good  way  toward 
showing  that  these  phenomena  are  the  necessary  out- 
growth of  the  conception. 

By  analysis  and  synthesis  Newton  proved  the  white  light 
of  the  sun  to  be  a  skein  of  many  colors.  The  cause  of 
color  was  a  question  which  immediately  occupied  his 
thoughts;  and  here,  as  in  other  cases,  he  freely  resorted  to 
hypothesis.  He  saw,  with  his  mind's  eye,  hisluminiferous 
corpuscles  crossing  the  bodily  eye,  and  imparting  successive 
shocks  to  the  retina  behind.  To  differences  of  "bigness" 
in  the  light-awakening  molecules  Newton  ascribed  the 
different  color-sensations.  In  the  undulatory  theory  we 
are  also  confronted  with  the  question  of  color;  and  here 
again,  to  inform  and  guide  us,  we  have  the  analogy  of 
sound.  Aerial  waves  of  different  lengths,  or  periods, 
produce  notes  of  different  pitch;  and  to  differences  of 
wave-length  in  that  mysterious  medium,  the  all-pervading 
ether,  differences  of  color  are  ascribed.  Hooke  had  already 
discoursed  of  "  a  very  quick  motion  that  causes  light,  as 
well  as  a  more  robust  that  causes  heat."  Newton  had 
ascribed  the  sensation  of  red  to  the  shock  of  his  grossest, 
and  that  of  violet  to  the  shock  of  his  finest  luminiferous 
projectiles,  Defining  the  one,  and  displacing  the  other  of 


THE  SKY.  101 

these  notions,  the  wave-theory  affirms  red  to  be  produced 
by  the  largest,  and  violet  by  the  smallest  waves  of  the 
visible  spectrum.  The  theory  of  undulation  had  to 
encounter  that  fierce  struggle  for  existence  which  all  great 
changes  of  doctrine,  scientific  or  otherwise,  have  had  to 
endure.  Mighty  intellects,  following  the  mightiest  of  them 
all,  were  arrayed  against  it.  But  the  more  it  was  discussed 
the  more  it  grew  in  strength  and  fa,vor,  until  it  finally 
supplanted  its  formidable  rival.  No  competent  scientific 
man  at  the  present  day  accepts  the  theory  of  emission,  or 
refuses  to  accept  the  theory  of  undulation. 

Boyle  and  Hooke  had  been  fruitful  experimenters  on 
those  beautiful  iridescences  known  as  the  "colors  of  thin 
plates."  The  rich  hues  of  the  thin-blown  soap-bubble,  of  oil 
floating  on  water,  and  of  the  thin  layer  of  oxide  on  molten 
lead,  are  familiar  illustrations  of  these  iris  colors.  Hooke 
showed  that  all  transparent  films,  if  only  thin  enough,  dis- 
played such  colors;  and  he  proved  that  the  particular  color 
displayed  depended  upon  the  thickness  of  the  film.  Pass- 
ing from  solid  and  liquid  films  to  films  of  air,  he  says: 
"Take  two  small  pieces  of  ground  and  polished  looking- 
glass  plate,  each  about  the  bigness  of  a  shilling;  take 
these  two  dry,  and  with  your  forefingers  and  thumbs  press 
them  very  hard  and  close  together,  and  you  shall  find  that 
when  they  approach  each  other  very  near,  there  will  appear 
several  irises  or  colored  lines."  Newton,  bent  on  knowing 
the  exact  relation  between  the  thickness  of  the  film  and  the 
color  it  produced,  varied  Hooke's  experiment.  Taking  two 
pieces  of  glass,  the  one  plane  and  the  other  very  slightly 
curved,  and  pressing  both  together,  he  obtained  a  film  of 
air  of  gradually  increasing  thickness  from  the  place  of  con- 
tact outward.  "  As  he  expected,  he  found  the  place  of  con- 
tact surrounded  by  a  series  of  colored  circles,  still  known 
all  over  the  world  as  "  Newton's  rings."  The  colors  of  his 
first  circle,  which  immediately  surrounded  a  black  central 
spot,  Newton  called  "colors  of  the  first  order;"  the  colors 
of  the  second  circle,  "  colors  of  the  second  order,"  and  so 
on.  With  unrivaled  penetration  and  apparent  success,  he 
applied  his  theory  of  "fits"  to  the  explanation  of  the 
"  rings."  Here,  however,  the  only  immortal  parts  of  his 
labors  are  his  facts  and  measurements;  his  theory  has  dis- 
appeared. It  was  reserved  for  the  illustrious  Thomas 
Young,  a  man  of  intellectual  caliber  resembling  that  of 


]  02  FRA  GMENTS  OF  SCIENCE. 

Newton  himself,  to  prove  that  the  rings  were  produced  by 
the  mutual  action — in  technical  phrase,  '•'  interference" — 
of  the  light  waves  reflected  at  the  two  surfaces  of  the  film 
of  air  inclosed  between  the  plane  and  convex  glasses.  The 
colors  of  thin  plates  were  "residual  colors" — survivals  of 
the  white  light  after  the  ravages  of  interference.  Young 
soon  translated  the  theory  of  "  fits  "  into  that  of  "  waves; " 
the  measurements  pertaining  to  the  former  being  so  accurate 
as  to  render  them  immediately  available  for  the  purposes 
of  the  latter. 

It  is  here  that  Newton's  researches  and  opinions  touch 
the  subject  of  this  article.  The  color  nearest  to  the  black 
spot,  in  the  experiment  above  described,  was  a  faint  blue — 
"blue  of  the  first  order" — corresponding  to  the  film  of  air 
when  thinnest.  If  a  solid  or  liquid  film,  of  the  thickness 
requisite  to  produce  this  color,  were  broken  into  bits  and 
scattered  in  the  air,  Newton  inferred  that  the  tiny  frag- 
ments would  display  the  blue  color.  Tantamount  to  this, 
he  considered,  was  the  action  of  minute  water-particles  in 
the  incipient  stage  of  their  condensation  from  aqueous 
vapor.  Such  particles  suspended  in  our  atmosphere  ought, 
he  supposed,  to  generate  the  serenest  skies.  Newton  does 
not  appear  to  have  bestowed  much  thought  upon  this  sub- 
ject; for  to  produce  the  particular  blue  which  he  regarded 
as  sky-blue,  thin  plates  with  parallel  surfaces  would  be  re- 
quired. The  notion  that  cloud-particles  are  hollow  spheres, 
or  vesicles,  is  prevalent  on  the  Continent,  but  it  never 
made  any  way  among  the  scientific  men  of  England.  De 
Saussure  thought  that  he  had  actually  seen  the  cloud-ves- 
icles, and  Faraday,  as  I  learned  from  himself,  believed  that 
he  had  once  confirmed  the  observation  of  the  illustrious 
Alpine  traveler.  During  my  long  acquaintance  with  the 
atmosphere  of  the  Alps  I  have  "often  sought  for  these 
aqueous  bladders,  but  have  never  been  able  to  find  them. 
Clausius  once  published  a  profound  essay  on  the  colors  of 
the  sky.  The  assumption  of  small  water"drops,  he  proved, 
would  lead  to  optical  consequences  entirely  at  variance 
with  facts.  For  a  time,  therefore,  he  closed  with  the  idea 
of  vesicles,  and  endeavored  to  deduce  from  them  the  blue 
of  the  firmament  and  the  morning  and  evening  red. 

It  is  not,  however,  necessary  to  invoke  the  blue  of  the 
first  order  to  explain  the  color  of  the  sky;  nor  is  it  neces- 
sary to  impose  upon  condensing  vapor  the  difficult,  if  .not 


THK  8KT.  103 

impossible,  task  of  forming  bladders,  when  it  passes  into 
the  liquid  condition.  Let  us  examine  the  subject.  Eau- 
de-Cologne  is  prepared  by  dissolving  aromatic  gums  or  resins 
in  alcohol.  Dropped  into  water,  the  scented  liquid  imme- 
diately produces  a  white  cloudiness,  due  to  the  precipitation 
of  the  substances  previously  held  in  solution.  The  solid 
particles  are,  however,  comparatively  gross;  but  by  dimin- 
ishing the  quantity  of  the  dissolved  gum,  the  precipitate 
may  be  made  to  consist  of  extremely  minute  particles. 
Briicke,  for  example,  dissolved  gum-mastic,  in  certain 
proportions,  in  alcohol,  and  carefully  dropping  his  solution 
into  a  beaker  of  water,  kept  briskly  stirred,  he  was  able  to 
reduce  the  precipitate  to  an  extremely  fine  state  of  division. 
The  particles  of  mastic  can  by  no  means  be  imagined  as 
forming  bladders.  Still,  against  a  dark  ground — black  vel- 
vet, for  example — the  water  that  contains  them  shows  a 
distinctly  blue  color.  The  bluish  color  of  many  liquids  is 
produced  in  a  similar  manner.  Thin  milk  is  an  example. 
Blue  eyes  are  also  said  to  be  simply  turbid  media.  The 
rocks  over  which  glaciers  pass  are  finely  ground  and  pul- 
verized by  the  ice,  or  the  stony  emery  imbedded  in  it;  and 
the  river  which  issues  from  the  snout  of  every  glacier  is 
laden  with  suspended  matter.  When  such  glacier  water  is 
placed  in  a  tall  glass  jar,  and  the  heavier  particles  are  per- 
mitted to  subside,  the  liquid  column,  when  viewed  against  a 
dark  background,  has  a  decidedly  bluish  tinge.  The  excep- 
tional blueness  of  the  lake  of  Geneva,  which  is  fed  with 
glacier  water,  may  be  due,  in  part,  to  particles  small  enough 
to  remain  suspended  long  after  their  larger  and  heavier 
companions  have  sunk  to  the  bottom  of  the  lake. 

We  need  not,  however,  resort  to  water  for  the  production 
of  the  color.  We  can  liberate,  in  air,  particles  of  a  size 
capable  of  producing  a  blue  as  deep  and  pure  as  the  azure 
of  the  firmament.  In  fact,  artificial  skies  may  be  thus 
generated,  which  prove  their  brotherhood  with  the  natural 
sky  by  exhibiting  all  its  phenomena.  There  are  certain 
chemical  compounds — aggregates  of  molecules — the  con- 
stituent atoms  of  which  are  readily  shaken  asunder  by  the 
impact  of  special  waves  of  light.  Probably,  if  not  certainly, 
the  atoms  and  the  waves  are  so  related  to  each  other,  as 
regards  vibrating  period,  that  the  wave-motion  can  accumu- 
late until  it  becomes  disruptive.  A  great  number  of  sub- 
stances might  be  mentioned  whose  vapors,  when  mixed^with 


104  mA&MWy®  OF  SCIENCE. 

air  and  subjected  to  the  action  of  a  solar  or  an  electric  beam, 
are  thus  decomposed,  the  products  of  decomposition  hang- 
ing as  liquid  or  solid  particles  in  the  beam  which  generates 
them.  And  here  I  must  appeal  to  the  inner  vision  already 
spoken  of.  Kemembering  the  different  sizes  of  the  waves 
of  light,  it  is  not  difficult  to  see  that  our  minute  particles 
are  larger  with  respect  to  some  waves  than  to  others.  In 
the  case  of  water,  for  example,  a  pebble  will  intercept  and 
reflect  a  larger  fractional  part  of  a  ripple  than  of  a  larger 
wave.  We  have  now  to  imagine  light-undulations  of  dif- 
ferent dimensions,  but  all  exceedingly  minute,  passing 
through  air  laden  with  extremely  small  particles.  It  is 
plain  that  such  particles,  though  scattering  portions  of  all 
the  waves,  will  exert  their  most  conspicuous  action  upon 
the  smallest  ones;  and  that  the  color-sensation  answering 
to  the  smallest  waves — in  other  words,  the  color  blue — 
will  be  predominant  in  the  scattered  light.  This  harmon- 
izes perfectly  with  what  we  observe  in  the  firmament.  The 
sky  is  blue,  but  the  blue  is  not  pure.  On  looking  at  the 
sky  through  a  spectroscope,  we  observe  all  the  colors  of  the 
spectrum;  blue  is  merely  the  predominant  color.  By  means 
of  our  artificial  skies  we  can  take,  as  it  were,  the  firmament 
in  our  hands  and  examine  it  at  our  leisure.  Like  the  nat- 
ural sky,  the  artificial  one  shows  all  the  colors  of  the  spec- 
trum, but  blue  in  excess.  Mixing  very  small  quantities  of 
vapor  with  air,  and  bringing  the  decomposingluminous  beam 
into  action,  we  produce  particles  too  small  to  shed  any  sen- 
sible light,  but  which  may,  and  doubtless  do,  exert  an 
action  on  the  ultra-violet  waves  of  the  spectrum.  We  can 
watch  these  particles,  or  rather  the  space  they  occupy,  till 
they  grow  to  a  size  able  to  yield  the  firmamental  azure. 
As  the  particles  grow  larger  under  the  continued  action  of 
the  light,  the  azure  becomes  less  deep:  while  later  on  a 
milkiness,  such  as  we  often  observe  in  nature,  takes  the 
place  of  the  purer  blue.  Finally  the  particles  become 
large  enough  to  reflect  all  the  light-waves,  and  then  the 
suspended  "actinic  cloud"  diffuses  white  light. 

It  must  occur  to  the  reader  that  even  in  the  absence  of 
definite  clouds  there  are  considerable  variations  in  the  hue 
of  the  firmament.  Everybody  knows,  moreover,  that  as 
the  sky  bends  toward  the  horizon,  the  purer  blue  is  im- 
paired. To  measure  the  intensity  of  the  color  De  Saussure 
invented  a  cyanometer,  and  Humboldt  has  given  us  a 


TKE  SET.  105 

mathematical  formula  to  express  the  diminution  of  the 
blue,  in  arcs  drawn  east  and  west  from  the  zenith  down- 
ward. This  diminution  is  a  natural  consequence  of  the 
predominance  of  coarser  particles  in  the  lower  regions  of 
the  atmosphere.  Were  the  particles  which  produce  the 
purer  celestial  vault  all  swept  away,  we  should,  unless 
helped  by  what  has  been  called  "cosmic  dust,"  look  into 
the  blackness  of  celestial  space.  And  were  the  whole 
atmosphere  abolished  along  with  its  suspended  matter,  we 
should  have  the  "  blackness  "spangled  with  steady  stars;  for 
the  twinkling  of  the  stars  is  caused  by  our  atmosphere. 
Now,  the  higher  we  ascend,  the  more  do  we  leave  behind 
us  the  particles  which  scatter  the  light;  the  nearer,  in  fact, 
do  we  approach  to  that  vision  of  celestial  space  mentioned 
a  moment  ago.  Viewed,  therefore,  from  the  loftiest 
Alpine  summits,  the  firmamental  blue  is  darker  than  it  is 
ever  observed  to  be  from  the  plains. 

It  is  thus  shown  that  by  the  scattering  action  of  minute 
particles  the  blue  of  the  sky  can  be  produced;  but  there 
is  yet  more  to  be  said  upon  the  subject.  Let  the  natural 
sky  be  looked  at  on  a  fine  day  through  a  piece  of  trans- 
parent Iceland  spar  cut  into  the  form  known  as  a  Nicol 
prism.  It  may  be  well  to  begin  by  looking  through  the 
prism  at  a  snow  slope,  or  a  white  wall.  Turning  the  prism 
round  its  axis,  the  light  coming  from  these  objects  does 
not  undergo  any  sensible  change.  But  when  the  prism  is 
directed  toward  the  sky  the  great  probability  is  that,  on 
turning  it,  variations  in  the  amount  of  light  reaching  the 
eye  will  be  observed.  Testing  various  portions  of  the  sky 
with  due  diligence,  we  at  length  discover  one  particular 
direction  where  the  difference  of  illumination  becomes  a 
maximum.  Here  the  Nicol,  in  one  position,  seems  to 
offer  no  impediment  to  the  passage  of  the  skylight,  while, 
when  turned  through  an  arc  of  ninetv  degrees  from  this 
position,  the  light  is  almost  •  entirely  quenched.  We  soon 
discern  that  the  particular  line  of  vision  in  which  this 
maximum  difference  is  observed  is  perpendicular  to  the 
direction  of  the  solar  rays.  The  Nicol  acts  thus  upon  sky- 
light because  that  light  is  polarized,  while  the  light  from 
the  white  wall  or  the  white  snow,  being  unpolarized,  is  not 
affected  by  the  rotation  of  the  prism. 

In  the  case  of  our  manufactured  sky  not  only  is  the 
azure  of  the  firmament  reproduced,  but  these  phenomena 


1 06  PR  A  GMENTS  Of  SCIENCE. 

of  polarization  are  observed  even  more  perfectly  than  in 
the  natural  sky.  When  the  air-space  from  which  our  best 
artificial  azure  is  emitted  is  examined  with  the  Nicol  prism, 
the  blue  light  is  found  to  be  completely  polarized  at  right 
angles  to  the  illuminating  beam.  The  artificial  sky  may, 
in  fact,  be  employed  as  a  second  Nicol,  between  which  and 
a  prism  held  in  the  hand  many  of  the  beautiful  chromatic 
phenomena  observed  in  an  ordinary  polariscope  may  be 
reproduced. 

Let  us  now  complete  our  thesis  by  following  the  larger 
light-waves,  which  have  been  able  to  pass  among  the  aerial 
particles  with  comparatively  little  fractional  loss.  With- 
out going  beyond  inferential  considerations,  we  can  state 
what  must  occur.  The  action  of  the  particles  upon  the 
solar  light  increases  with  the  atmospheric  distances  traversed 
by  the  sun's  rays.  The  lower  the  sun,  therefore,  the 
greater  the  action.  The  shorter  waves  of  the  spectrum 
being  more  and  more  withdrawn,  the  tendency  is  to  give 
the  longer  waves  an  enhanced  predominance  in  the  trans- 
mitted light.  The  tendency,  in  other  words,  of  this  light, 
as  the  rays  traverse  ever-increasing  distances,  is  more  and 
more  toward  red.  This,  I  say,  might  be  stated  as  an  infer- 
ence, but  it  is  borne  out  in  the  most  impressive  manner  by 
facts.  When  the  Alpine  sun  is  setting,  or,  better  still,  some 
time  after  he  has  set,  leaving  the  limbs  and  shoulders  of  the 
mountains  in  shadow,  while  their  snowy  crests  are  bathed 
by  the  retreating  light,  the  snow  glows  with  a  beauty  and 
solemnity  hardly  equaled  by  any  other  natural  phenomenon. 
So,  also,  when  first  illumined  by  the  rays  of  the  unrisen 
sun,  the  mountain  heads,  under  favorable  atmospheric  con- 
ditions, shine  like  rubies.  And  all  this  splendor  is  evoked 
by  the  simple  mechanism  of  minute  particles,  themselves 
without  color,  suspended  in  the  air.  Those  who  referred 
the  extraordinary  succession  of  atmospheric  glows,  wit- 
nessed some  years  ago,  to  a  vast  and  violent  discharge  of 
volcanic  ashes,  were  dealing  with  "a  true  cause/'  The 
fine  floating  residue  of  such  ashes  would,  undoubtedly,  be 
able  to  produce  the  effects  ascribed  to  it.  Still,  the  mechan- 
ism necessary  to  produce  the  morning  and  the  evening  red, 
though  of  variable  efficiency,  is  always  present  in  the  atmos- 
phere. I  have  seen  displays,  equal  in  magnificence  to  the 
finest  of  those  above  referred  to,  when  there  was  no  special 
volcanic  outburst  to  which  they  could  be  referred,  it  was 


VOYAGE  TO  ALGERIA.  107 

the  long-continued  repetition  of  the  glows  which  rendered 
the  volcanic  theory  highly  probable. 


CHAPTER  VI. 

VOYAGE  TO  ALGERIA  TO   OBSERVE  THE  ECLIPSE. 
1870. 

THE  OPENING  of  the  Eclipse  Expedition  was  not  pro- 
pitious. Portsmouth,  on  Monday,  December  5,  1870,  was 
swathed  by  fog,  which  was  intensified  by  smoke,  and  trav- 
ersed by  a  drizzle  of  fine  rain.  At  six  P.M.  I  was  on  board 
the  Urgent.  On  Tuesday  morning  the  weather  was  too 
thick  to  permit  of  the  ship  being  swung  and  her  com- 
passes calibrated.  The  admiral  of  the  port,  a  man  of  very 
noble  presence,  came  on  board.  Under  his  stimulus  the 
energy  which  the  weather  had  damped  appeared  to  become 
more  active,  and  soon  after  his  departure  we  steamed  down 
to  Spithead.  Here  the  fog  had  so  far  lightened  as  to  en- 
able the  officers  to  swing  the  ship. 

At  three  P.M.  on  Tuesday,  December  6,  we  got  away, 
gliding  successively  past  Whitecliff  Bay,  Bembridge,  San- 
down,  Shanklin,  Ventuor,  and  St.  Catherine's  Lighthouse. 
On  Wednesday  morning  we  sighted  the  Isle  of  Ushant,  on 
the  French  side  of  the  Channel.  The  northern  end  of  the 
island  has  been  fretted  by  the  waves  into  detached  tower- 
like  masses  of  rock  of  very  remarkable  appearance.  In  the 
Channel  the  sea  was  green,  and  opposite  Ushant  it  was  a 
brighter  green.  On  Wednesday  evening  we  committed 
ourselves  to  the  bay  of  Biscay.  The  roll  of  the  Atlantic 
was  full,  but  not  violent.  There  had  been  scarcely  a  gleam 
of  sunshine  throughout  the  day,  but  the  cloud-forms  were 
fine,  and  their  apparent  solidity  impressive.  On  Thursday 
morning  the  green  of  the  sea  was  displaced  by  a  deep  in- 
digo blue.  The  whole  of  Thursday  we  steamed  across  the 
bay.  We  had  little  blue  sky,  but  the  clouds  were  again  grand 
and  varied — cimis,  stratus,  cumulus,  and  nimbus,  we  had 
them  all.  Dusty  hair~like  trails  were  sometimes  dropped 
from  the  distant  clouds  to  the  sea.  These  were  falling 
showers,  and  they  sometimes  occupied  the  whole  horizon, 


lOg  mAGMKXTS  OF  SCIENCE. 

while  we  steamed  across  the  rainless  circle  which  was  thus 
surrounded.  Sometimes  we  plunged  into  the  rain,  and  once 
or  twice,  by  slightly  changing  our  course,  avoided  a  heavy 
shower.  From  time  to  time  perfect  rainbows  spanned  the 
heavens  from  side  to  side.  At  times  a  bow  would  appear 

i  •  in  fragments,  showing  the  keystone  of  the  arch  midway  in 
air,  and  its  two  buttresses  on  the  horizon.  In  all  cases  the 
light  of  the  bow  could  be  quenched  by  a  Nicol's  prism,  with 
its  long  diagonal  tangent  to  the  arc.  Sometimes  gleaming 
patches  of  the  firmament  were  seen  amid  the  clouds.  AVhen 
viewed  in  the  proper  direction,  the  gleam  could  be 
quenched  by  a  Nicol's  prism,  a  dark  aperture  being  thus 
opened  into  stellar  space. 

At  sunset  on  Thursday  the  denser  clouds  were  fiercely 
fringed,  while  through  the  lighter  ones  seemed  to  issue  the 
glow  of  a  conflagration.  On  Friday  morning  we  sighted 

*  Cape  Finisterre — the  extreme  end  of  the  arc  which  sweeps 
from  Ushant  round  the  bay  of  Biscay.  Calm  spaces  of 
blue,  in  which  floated  quietly  scraps  of  cumuli,  were  behind 
us,  but  in  front  of  us  was  a  horizon  of  portentous  darkness. 
It  continued  thus  threatening  throughout  the  day.  Toward 
evening  the  wind  strengthened  to  a  gale,  and  at  dinner  it 
was  difficult  to  preserve  the  plates  and  dishes  from  destruc- 
tion. Our  thinned  company  hinted  that  the  rolling  had 
other  consequences.  It  was  very  wild  when  AVC  went  to 
bed.  I  slumbered  and  slept,  but  after  some  time  was  ren- 
dered anxiously  conscious  that  my  body  had  become  a  kind 
of  projectile,  with  the  ship's  side  for  a  target.  I  gripped 
the  edge  of  my  berth  to  save  myself  from  being  thrown 
out.  Outside,  I  could  hear  somebody  say  that  he  had  been 
thrown  from  his  berth,  and  sent  spinning  to  the  other  side 
of  the  saloon.  The  screw  labored  violently  amid  the 
lurching;  it  incessantly  quitted  the  water,  and,  twirling  in 
the  air,  rattled  against  its  bearings,  causing  the  ship  to 
shudder  from  stem  to  stern.  At  times  the  waves  struck 
us,  not  with  the  soft  impact  which  might  be  expected 
from  a  liquid,  but  with  the  sudden  solid  shock  of  batter- 
ing-rams.  "  No  man  knows  the  force  of  water,"  said  one 
of  the  officers,  "  until  he  has  experienced  a  storm  at  sea." 
These  blows  followed  each  other  at  quicker  intervals,  the 
screw  rattling  after  each  of  them,  until,  finally,  the  delivery 
of  a  heavier  stroke  than  ordinary  seemed  to  reduce  the 
saloon  to  chaos.  Furniture  crashed,  glasses  rang,  and 


VOYAGE   TO  ALGERIA.  109 

alarmed  inquiries  immediately  followed.     Amid  the  noises^) 
I    heard   one   note  of   forced   laughter;   it   sounded   very 
ghastly.      Men    tramped    through    the   saloon,    and  busy 
voices  were  heard  aft,  as  if  something  there  had  gone  wrong. 

I  rose,  and  not  without  difficulty  got  into  my  clothes. 
In  the  after-cabin,  under  the  superintendence  of  the  able 
and  energetic  navigating  lieutenant,  Mr.  Brown,  a  group 
of  blue-jackets  were  working-  at  the  tiller-ropes.  These 
had  become  loose,  and  the  helm  refused  to  answer  the 
wheel.  High  moral  lessons  might  be  gained  on  shipboard, 
by  observing  what  steadfast  adherence  to  an  object  can 
accomplish,  and  what  large  effects  are  heaped  up  by  the 
addition  of  infinitesimals.  The  tiller-rope,  as  the  blue- 
jackets strained  in  concert,  seemed  hardly  to  move;  still  it 
did  move  a  little,  until  finally,  by  timing  the  pull  to  the 
lurching  of  the  ship,  the  mastery  of  the  rudder  was  ob- 
tained. I  had  previously  gone  on  deck.  Round  the 
saloon-door  were  a  few  members  of  the  eclipse  party,  who 
seemed  in  no  mood  for  scientific  observation.  Nor  did  I; 
but  I  wished  to  see  the  storm.  I  climbed  the  steps  to 
the  poop,  exchanged  a  word  with  Captain  Toynbee,  the 
only  member  of  the  party  to  be  seen  on  the  poop,  and  by 
his  direction  made  toward  a  cleat  not  far  from  the  wheel.* 
Round  it  I  coiled  my  arms.  With  the  exception  of 
the  men  at  the  wheel,  who  stood  as  silent  as  corpses,  I 
was  alone. 

I  had  seen  grandeur  elsewhere,  but  this  was  a  new  form 
of  grandeur  to  me.  The  Urgent  is  long  and  narrow, 
and  during  our  expedition  she  lacked  the  steadying 
influence  of  sufficient  ballast.  She  was  for  a  time  practi- 
cally rudderless,  and  lay  in  the  trough  of  the  sea.  I  could 
see  the  long  ridges,  with  some  hundreds  of  feet  between 
their  crests,  rolling  upon  the  ship  perfectly  parallel  to  her 
sides.  As  they  approached,  they  so  grew  upon  the  eye  as 
to  render  the  expression  "  mountains  high "  intelligible. 
At  all  events,  there  was  no  mistaking  their  mechanical 
might,  as  they  took  the  ship  upon  their  shoulders,  and  ,/ 
swung  her  like  a  pendulum.  The  deck  sloped  sometimes 
at  an  angle  which  I  estimated  at  over  forty-five  degrees; 
wanting  my  previous  Alpine  practice,  I  should  have  felt 
less  confidence  in  my  grip  of  the  cleat.  Here  and  there 

*  The  cleat  is  a  T-shaped  n^88  of  metal  employed  for  the  fasten- 
ing of  ropes. 


1 10  FSA  GMENTS  OF  SCIENCE. 

the  long  rollers  were  tossed  by  interference  into  heaps  of 
greater  height.  The  wind  caught  their  crests,  and  scat- 
tered them  over  the  sea,  the  whole  surface  of  which  was 
seething  white.  The  aspect  of  the  clouds  was  a  fit  accom- 
paniment to  the  fury  of  the  ocean.  The  moon  was  almost 
full — at  times  concealed,  at  times  revealed,  as  the  scud  flew 
wildly  over  it.  These  things  appealed  to  the  eye,  while  the 
ear  was  filled  by  the  groaning  of  the  screw  and  the  whistle 
and  boom  of  the  storm. 

Nor  was  the  outward  agitation  the  only  object  of  interest 
to  me.  I  was  at  once  subject  and  object  to  myself,  and 
watched  with  intense  interest  the  workings  of  my  own 
mind.  The  Urgent  is  an  elderly  ship.  She  had  been 
built,  I  was  told,  by  a  contracting  firm  fo  some  foreign 
government,  and  had  been  diverted  from  her  first  purpose 
when  converted  into  a  troop-ship.  She  had  been  for  some 
time  out  of  work,  and  I  had  heard  that  one  of  her  boilers, 
at  least,  needed  repair.  Our  scanty  but  excellent  crew, 
moreover,  did  not  belong  to  the  Urgent,  but  had  been 
gathered  from  other  ships.  Our  three  lieutenants  were 
also  volunteers.  All  this  passed  swiftly  through  my  mind 
as  the  steamer  shook  under  the  blows  of  the  waves,  and  I 
thought  that  probably  no  one  on  board  could  say  how 
much  of  this  thumping  and  straining  the  Urgent  would 
be  able  to  bear.  This  uncertainty  caused  me  to  look 
steadily  at  the  worst,  and  I  tried  to  strengthen  myself  in 
the  face  of  it. 

But  at  length  the  helm  laid  hold  of  the  water,  and  the 
ship  was  got  gradually  round  to  face  the  waves.  The 
rolling  diminished,  a  certain  amount  of  pitching  taking  its 
place.  Our  speed  had  fallen  from  eleven  knots  to  two.  I 
went  again  to  bed.  After  a  space  of  calm,  when  we  seemed 
crossing  the  vortex  of  a  storm,  heavy  tossing  recommenced. 
I  was  afraid  to  allow  myself  to  fall  asleep;  as  my  berth  was 
high,  and  to  be  pitched  out  of  it  might  be  attended  with 
bruises,  if  not  with  fractures.  From  Friday  at  noon  to 
Saturday  at  noon  we  accomplished  sixty-six  miles,  or  an 
average  of  less  than  three  miles  an  hour.  I  overheard  the 
sailors  talking  about  this  storm.  The  Urgent,  according 
to  those  that  knew  her,  had  never  previously  experienced 
anything  like  it.  * 

*  There  is,  it  will  be  seen,  a  fair  agreement  between- these  im- 
pressions and  those  so  vigorously  described  by  a  scientific  corre- 
spondent of  the 


VOYAGE   TO  ALGERIA.  HI 

All  through  Saturday  the  wind,  though  somewhat  sobered, 
blew  dead  against  us.  The  atmospheric  effects  were  ex- 
ceedingly fine.  The  cumuli  resembled  mountains  in  shape,  t 
and  their  peaked  summits  shone  as  white  as  Alpine  snows.  \ 
At  one  place  this  resemblance  was  greatly  strengthened  by 
a  vast  area  of  cloud,  uniformly  illuminated,  and  lying  like 
a  neve  below  the  peaks.  From  it  fell  a  kind  of  cloud-river 
strikingly  like  a  glacier.  The  horizon  at  sunset  was 
remarkable — spaces  of  brilliant  green  between  clouds  of 
fiery  red.  Rainbows  had  been  frequent  throughout  the 
day,  and  at  night  a  perfectly  continuous  lunar  bow  spanned 
the  heavens  from  side  to  side.  Its  colors  were  feeble;  but, 
contrasted  with  the  black  ground  against  which  it  rested, 
its  luminousness  was  extraordinary. 

Sunday  morning  found  us  opposite  to  Lisbon,  and  at " 
midnight  we  rounded  Cape  St.  Vincent,  where  the  lurching 
seemed  disposed  to  recommence.  Through  the  kindness 
of  Lieutenant  Walton,  a  cot  had  been  slung  for  me.  It 
hung  between  a  tiller-wheel  and  a  flue,  and  at  one  A.M.  I 
was  roused  by  the  banging  of  the  cot  against  its  boundaries. 
But  the  wind  was  now  behind  us,  and  we  went  along  at  a 
speed  of  eleven  knots.  We  felt  certain  of  reaching  Cadiz 
by  three.  But  a  new  lighthouse  came  in  sight,  which  some 
affirmed  to  be  Cadiz  Lighthouse,  while  the  surrounding 
houses  were  declared  to  be  those  of  Cadiz  itself.  Out  of 
deference  to  these  statements,  the  navigating  lieutenant 
changed  his  course,  and  steered  for  the  place.  A  pilot 
came  on  board,  and  he  informed  us  that  we  were  before 
the  mouth  of  the  Guadalquivir,  and  that  the  lighthouse 
was  that  of  Cipidna.  Cadiz  was  still  some  eighteen  miles 
distant. 

We  steered  toward  the  city,  hoping  to  get  into  the 
harbor  before  dark.  But  the  pilot  who  would  have  guided 
us  had  been  snapped  up  by  another  vessel,  and  we  did  not 
get  in.  We  beat  about  during  the  night,  and  in  the  morn- 
ing found  ourselves  about  fifteen  miles  from  Cadiz.  The 
sun  rose  behind  the  city,  and  we  steered  straight  into  the 
light.  The  three-towered  cathedral  stood  in  the  midst, 
round  which  swarmed  apparently  a  multitude  of  chimney- 
stacks.  A  nearer  approach  showed  the  chimneys  to  be 
small  turrets.  A  pilot  was  taken  on  board;  for  there  is  a 
dangerous  shoal  in  the  harbor.  The  appearance  of  the 
town,  as  the  sun  shone  upon  its  white  and  lofty  walls,  was 


H2  FRAGMENTS  OF  SCIENCE. 

singularly  beautiful.  We  cast  anchor;  some  officials 
arrived  and  demanded  a  clean  bill  of  health.  We  had 
none.  They  would  have  nothing  to  do  with  us;  so  the 
yellow  quarantine  flag  was  hoisted,  and  we  waited  for  per- 
mission to  land  the  Cadiz  party.  After  some  hours'  delay 
the  English  consul  and  vice-consul  came  on  board,  and 
with  them  a  Spanish  officer  ablaze  with  gold  lace  and 
decorations.  Under  slight  pressure  the  requisite  permis- 
sion had  been  granted.  We  landed  our  party,  and  in  the 
afternoon  weighed  anchor.  Thanks  to  the  kindness  of  our 
excellent  paymaster,  I  was  here  transferred  to  a  more 
roorny  berth. 

Cadiz  soon  sank  beneath  the  sea,  and  we  sighted  in  suc- 
cession Cape  Trafalgar,  Tarifa,  and  the  revolving  light  of 
Ceuta.  The  water  was  very  calm,  and  the  moon  rose  in  a 
.quiet  heaven.  She  swung  with  her  convex  surface  down- 
ward, the  common  boundary  between  light  and  shadow 
being  almost  horizontal.  A  pillar  of  reflected  light  shim- 
mered up  to  us  from  the  slightly  rippled  sea.  I  had  pre- 
viously noticed  the  phosphorescence  of  the  water,  but  to- 
night it  was  stronger  than  usual,  especially  among  the  foam 
at  the  bows.  A  bucket  let  down  into  the  sea  brought  up 
a  number  of  the  little  sparkling  organisms  which  caused 
the  phosphorescence.  I  caught  some  of  them  in  my  hand. 
And  here  an  appearance  was  observed  which  was  new  to 
most  of  us,  and  strikingly  beautiful  to  all.  Standing  at 
the  bow  and  looking  forward,  at  a  distance  of  forty  or  fifty 
yards  from  the  ship,  a  number  of  luminous  streamers  were 
seen  rushing  toward  us.  On  nearing  the  vessel  they 
rapidly  turned,  like  a  comet  round  its  perihelion,  placed 
themselves  side  by  side,  and,  in  parallel  trails  of  light,  kept 
up  with  the  ship.  One  of  them  placed  itself  right  in  front 
of  the  bow  as  a  pioneer.  These  comets  of  the  sea  were 
joined  at  intervals  by  others.  Sometimes  as  many  as  six 
at  a  time  would  rush  at  us,  bend  with  extraordinary  rapidity 
round  a  sharp  curve,  and  afterward  keep  us  company.  I 
leaned  over  the  bow,  and  scanned  the  streamers  closely. 
The  frontal  portion  of  each  of  them  revealed  the  outline 
of  a  porpoise.  The  rush  of  the  creatures  through  the 
water  had  started  the  phosphorescence,  every  spark  of 
which  was  converted  by  the  motion  of  the  retina  into  a 
line  of  light.  Each  porpoise  was  thus  wrapped  in  a 
luminous  sheath.  The  phosphorescence  did  not  cease  a,t 


VOYAGE  TO  ALGERIA.  113 

the  creature's  tail,  but  was  carried  many  porpoise-lengths 
behind  it. 

To  our  right  we  had  the  "African  hills,  illuminated  by 
the  moon.  Gibraltar  Rock  at  length  became  visible,  but 
the  town  remained  long  hidden  by  a  belt  of  haze,  through 
which  at  length  the  brighter  lamps  struggled.  It  was 
like  the  gradual  resolution  of  a  nebula  into  stars.  As  the 
intervening  depth  became  gradually  less,  the  mist  vanished 
more  and  more,  and  finally  all  the  lamps  shone  through  it. 
They  formed  a  bright  foil  to  the  somber  mass  of  rock  above 
them.  The  sea  was  so  calm  and  the  scene  so  lovely  that 
Mr.  Huggins  and  myself  stayed  on  deck  till  near  midnight, 
when  the  ship  was  moored.  During  our  walking  to  and  i 
fro  a  striking  enlargement  of  the  disk  of  Jupiter  was 
observed,  whenever  the  heated  air  of  the  funnel  came  be- 
tween us  and  the  planet.  On  passing  away  from  the 
heated  air,  the  flat  dim  disk  would  immediately  shrink  to 
a  luminous  point.  The  effect  was  one  of  visual  persistence. 
The  retinal  image  of  the  planet  was  set  quivering  in  all 
azimuths  by  the  streams  of  heated  air,  describing  in  quick 
succession  minute  lines  of  light,  which  summed  themselves 
to  a  disk  of  sensible  area. 

At  six  o'clock  next,  morning,  the  gun  at  the  signal 
station  on  the  summit  of  the  rock,  boomed.  At  eight  the 
band  on  board  the  Trafalgar  training-ship,  which  was  in 
the  harbor,  struck  up  the  national  anthem;  and  immediately 
afterward  a  crowd  of  mite-like  cadets  swarmed  up  the 
rigging.  After  the  removal  of  the  apparatus  belonging  to 
the  Gibraltar  party  we  went  on  shore.  Winter  was  in 
England  when  we  left,  but  here  we  had  the  warmth  of 
summer.  The  vegetation  was  luxuriant — palm  trees,  cac- 
tuses, and  aloes,  all  ablaze  with  scarlet  flowers.  A  visit  to 
the  governor  was  proposed,  as  an  act  of  necessary  courtesy, 
and  I  accompanied  Admiral  Ommaney  and  Mr.  Huggins  to 
"  the  Convent,"  or  Government  House.  We  sent  in  our 
cards,  waited  for  a  time,  and  were  then  conducted  by  an 
orderly  to  his  excellency.  He  is  a  fine  old  man,  over  six 
feet  high,  and  of  frank  military  bearing.  He  received  us 
and  conversed  with  us  in  a  very  genial  manner.  He  took 
us  to  see  his  garden,  his  palms,  his  shaded  promenades, 
and  his  orange-trees  loaded  with  fruit,  in  all  of  which  he 
took  manifest  delight.  Evidently  "the  hero  of  Kars *^_ 
had  fallen  upon  quarters  after  his  own  heart.  He  appeared 


114  FRAGMENTS  OF  SCIENCE. 

full  of  good  nature,  and  engaged  us  on  the  spot  to  dine 
with  him  that  day. 

We  sought  the  town-major  for  a  pass  to  visit  the  lines. 
While  awaiting  his  arrival  I  purchased  a  stock  of  white 
glass  bottles,  with  a  view  to  experiments  on  the  color  of 
the  sea.  Mr.  Huggins  and  myself,  who  wished  to  see  the 
rock,  were  taken  by  Captain  Salmond  to  the  library,  where 
a  model  of  Gibraltar  is  kept,  and  where  we  had  a  useful 
preliminary  lesson.  At  the  library  we  met  Colonel  Maberly, 
a  courteous  and  kindly  man,  who  gave  us  good  advice  re- 
garding our  excursion.  He  sent  an  orderly  with  us  to  the 
entrance  of  the  lines.  The  orderly  handed  us  over  to  an 
intelligent  Irishman,  who  was  directed  to  show  us  every- 
thing that  we  desired  to  see,  and  to  hide  nothing  from  us. 
We  took  the  "  upper  line,"  traversed  the  galleries  hewn 
through  the  limestone;  looked  through  the  embrasures, 
which  opened  like  doors  in  the  precipice,  toward  the  hills 
of  Spain;  reached  St.  George's  hall,  and  went  still  higher, 
emerging  on  the  summit  of  one  of  the  noblest  cliffs  I  have 
ever  seen. 

Beyond  were  the  Spanish  lines,  marked  by  a  line  of 
white  sentry-boxes;  nearer  were  the  English  lines,  less  con- 
spicuously indicated;  and  between  -both  was  the  neutral 
ground.  Behind  the  Spanish  lines  rose  the  conical  hill 
called  the  Queen  of  Spain's  Chair.  The  general  aspect  of 
the  mainland  from  the  rock  is  bold  and  rugged.  Dou- 
bling back  from  the  galleries,  we  struck  upward  toward 
the  crest,  reached  the  signal  station,  where  we  indulged 
in  "  shandy-gaff "  and  bread  and  cheese.  Thence  to 
O'Hara's  Tower,  the  highest  point  of  the  rock.  It  was 
built  by  a  former  governor,  who,  forgetful  of  the  laws  of 
terrestrial  curvature,  thought  he  might  look  from  the  tower 
into  the  port  of  Cadiz.  The  tower  is  riven,  and  it  may  be 
climbed  along  the  edges  of  the  crack.  We  got  to  the  top 
of  it;  thence  descended  the  curious  Mediterranean  Stair — a 
zigzag,  mostly  of  steps  down  a  steeply  falling  slope,  amid 
palmetto  brush,  aloes,  and  prickly  pear. 

Passing  over  the  Windmill  Hill,  we  were  joined  at  the 
"  Governor's  Cottage  "  by  a  car,  and  drove  afterward  to  the 
lighthouse  at  Europa  Point.  The  tower  was  built,  I  be- 
lieve, by  Queen  Adelaide,  and  it  contains  a  fine  dioptric  ap- 
paratus of  the  first  order,  constructed  by  Messrs.  Chance,  of 
Birmingham.  At  the  appointed  hour  we  were  at  the  Con- 


VOYAGE  TO  ALGERIA.  115 

vent.  During  dinner  the  same  genial  traits  which  appeared 
in  the  morning  were  still  more  conspicuous.  The  freshness 
of  the  governor's  nature  showed  itself  best  when  he  spoke 
of  his  old  antagonist  in  arms,  Mouravieif.  Chivalry  in 
war  is  consistent  with  its  stern  prosecution.  These  two 
men  were  chivalrous,  and  after  striking  the  last  blow  be- 
came friends  forever.  Our  kind  and  courteous  reception 
at  Gibraltar  is  a  thing  to  be  remembered  with  pleasure. 

On  December  15  we  committed  ourselves  to  the  Med- 
iterranean. The  views  of  Gibraltar  with  which  we  are 
most  acquainted  represent  it  as  a  huge  ridge;  but  its  aspect, 
end  on,  both  from  the  Spanish  lines  and  from  the  other 
side,  is  truly  noble.  There  is  a  sloping  bank  of  sand  at 
the  back  of  the  rock,  which  I  was  disposed  to  regard  sim- 
ply as  the  debris  of  the  limestone.  I  wished  to  leb  myself 
down  upon  it,  but  had  not  the  time.  My  friend  Mr.  Busk, 
however,  assures  me  that  it  is  silica,  and  that  the  same 
sand  constitutes  the  adjacent  neutral  ground.  There  are 
theories  afloat  as  to  its  having  been  blown  from  Sahara. 
The  Mediterranean  throughout  this  first  day,  and  indeed 
throughout  the  entire  voyage  to  Oran,  was  of  a  less  deep  blue 
than  the  Atlantic.  Possibly  the  quantity  of  organisms  may 
have  modified  the  color.  At  night  the  phosphorescence  was 
startling,  breaking  suddenly  out  along  the  crests  of  the 
waves  formed  by  the  port  and  starboard  bows.  Its  strength 
was  not  uniform.  Having  flashed  brilliantly  for  a  time,  it 
would  in  part  subside,  and  afterward  regain  its  vigor. 
Several  large  phosphorescent  masses  of  weird  appearance 
also  floated  past. 

On  the  morning  of  the  16th  we  sighted  the  fort  and 
lighthouse  of  Marsa  el  Kibir,  and  beyond  them  the  white 
walls  of  Oran  lying  in  the  bight  of  a  bay,  sheltered  by 
dominant  hills.  The  sun  was  shining  brightly;  during 
our  whole  voyage  we  had  not  had  so  fine  a  day.  The  wis- 
dom which  had  led  us  to  choose  Oran  as  our  place  of  obser- 
vation seemed  demonstrated.  A  rather  excitable  pilot 
came  on  board,  and  he  guided  us  in  behind  the  mole, 
which  had  suffered  much  damage  the  previous  year  from 
an  unexplained  outburst  of  waves  from  the  Mediterranean. 
Both  port  and  bow  anchors  were  cast  in  deep  water. 
With  three  huge  hawsers  the  ship's  stem  was  made  fast  to 
three  gun-pillars  fixed  in  the  mole;  and  here  for  a  time  the 
Urgent  rested  from  her  labors. 


116  FRAGMENTS  OF  SCIENCE. 

M.  Janssen,  who  had  rendered  his  name  celebrated  by 
his  observations  of  the  eclipse  in  India  in  1868,  when  he 
showed  the  solar  flames  to  be  eruptions  of  incandescent 
hydrogen,  was  already  encamped  in  the  open  country  about 
eight  miles  from  Oran.  On  December  2  he  had  quitted 
Paris  in  a  balloon,  with  a  strong  young  sailor  as  his  assist- 
ant, had  descended  near  the  mouth  of  the  Loire,  seen  M. 
Gambetta,  and  received  from  him  encouragement  and  aid. 
On  the  day  of  our  arrival  his  encampment  was  visited  by  Mr. 
Huggins,  and  the  kind  and  courteous  engineer  of  the  port 
drove  me  subsequently,  in  his  own  phaeton,  to  the  place. 
It  bore  the  best  repute  as  regards  freedom  from  haze  and 
fog,  and  commanded  an  open  outlook;  but  it  was  inconven- 
ient for  us  on  account  of  its  distance  from  the  ship.  The 
place  next  in  repute  was  the  railway  station,  between  two 
and  three  miles  distant  from  the  mole.  It  was  inspected, 
but,  being  enclosed,  was  abandoned  for  an  eminence  in  an 
adjacent  garden,  the  property  of  Mr.  Hinshelwood,  a 
Scotchman  who  had  settled  some  years  previously  as  an  es- 
parto merchant  in  Oran.*  He,  in  the  most  liberal  man- 
ner, placed  his  grounds  at  the  disposition  of  the  party. 
Here  the  tents  were  pitched,  on  the  Saturday,  by  Captain 
Salmond  and  his  intelligent  corps  of  s.aji£ers,  the  instru- 
ments being  erected  on  the  Monday  under  cover  of  the 
tents. 

Close  to  the  railway  station  runs  a  new  loopholed  wall  of 
defense,  through  which  the  highway  passes  into  the  open 
country.  Standing  on  the  highway,  and  looking  south- 
ward, about  twenty  yards  to  the  right  is  a  small  bastionet, 
intended  to  carry  a  gun  or  two.  Its  roof  I  thought  would 
form  an  admirable  basis  for  my  telescope,  while  the  view 
of  the  surrounding  country  was  unimpeded  in  all  direc- 
tions. The  authorities  kindly  allowed  me  the  use  of  this 
bastionet.  Two  men,  one  a  blue-jacket  named  Elliot,  and 
the  other  a  marine  named  Hill,  were  placed  at  my  dis- 
posal by  Lieutenant  Walton;  and,  thus  aided,  on  .Monday 
morning  I  mounted  my  telescope.  The  instrument  was 
new  to  me,  and  some  hours  of  discipline  were  spent  in 
mastering  all  the  details  of  its  manipulation. 

Mr.  Huggins  joined  me,  and  we  visited  together  the  Arab 
quarter  of  Oran.  The  flat-roofed  houses  appeared  very 

*  Esparto  is  a  kind  of  grass  now  much  used  in  the  manufacture  of 
of  paper. 


VOYAGE  TO  ALGERIA.  117 

clean  and  white.  The  street  was  filled  with  loiterers,  and 
the  thresholds  were  occupied  by  picturesque  groups.  Some 
of  the  men  were  very  fine.  We  saw  many  straight,  manly 
fellows  who  must  have  been  six  feet  four  in  height.  They 
passed  us  witli  perfect  indifference,  evincing  no  anger,  sus- 
picion, or  curiosity,  hardly  caring  in  fact  to  glance  at  us 
as  we  passed.  In  one  instance  only  during  my  stay  at  Oran 
was  I  spoken  to  by  an  Arab.  He  was  a  tall,  good-humored 
fellow,  who  came  smiling  up  to  me,  and  muttered  some- 
thing about  "  les  Anglais."  The  mixed  population  of 
Oran  is  picturesque  in  the  highest  degree;  the  Jews,  rich 
and  poor,  varying  in  their  costumes  as  their  wealth  varies; 
the  Arabs  more  picturesque  still,  and  of  all  shades  of  com- 
plexion— the  negroes,  the  Spaniards,  the  French,  all 
grouped  together,  each  race  preserving  its  own  individu- 
ality, formed  a  picture  intensely  interesting  to  me. 

On  Tuesday,  the  20th,  I  was  early  at  the  bastionet. 
The  night  had  been  very  squally.  The  sergeant  of  the 
sappers  had  .taken  charge  of  our  key,  and  on  Tuesday 
morning  Elliot  went  for  it.  He  brought  back  the  intelli- 
gence that  the  tents  had  been  blown  down,  and  the  instru- 
ments overturned.  Among  these  was  a  large  and  valuable 
equatorial  from  the  Royal  Observatory,  Greenwich.  It 
seemed  hardly  possible  that  this  instrument,  with  its 
wheels  and  verniers  and  delicate  adjustments,  could  have 
escaped  uninjured  from  such  a  fall.  This,  however,  was 
the  case;  and  during  the  day  all  the  overturned  instru- 
ments were  restored  to  their  places,  and  found  to  be  in 
practical  working  order.  This  and  the  following  day  were 
devoted  to  incessant  schooling.  I  had  come  out  as  a 
general  stargazer,  and  not  with  the  intention  of  devoting 
myself  to  the  observation  of  any  particular  phenomenon. 
I  wished  to  see  the  whole — the  first  contact,  the  advance 
of  the  moon,  the  successive  swallowing  up  of  the  solar 
spots,  the  breaking  of  the  last  line  of  orescent  by  the  lunar 
mountains  into  Bailey's  beads,  the  advance  of  the  shadow 
through  the  air,  the  appearance  of  the  corona  and  prom- 
inences at  the  moment  of  totality,  the  radiant  streamers 
of  the  corona,  the  internal  structure  of  the  flames,  a  glance 
through  a  polariscope,  a  sweep  round  the  landscape  with 
the  naked  eye,  the  reappearance  of  the  solar  limb  through 
Bailey's  beads,  and,  finally,  the  retreat  of  the  lunar  shadow 
through  the  air. 


118  FRAGMENTS  OF  SCIENCE. 

I  was  provided  with  a  telescope  of  admirable  definition, 
mounted,  adjusted,  packed,  and  most  liberally  placed  at 
my  disposal  by  Mr.  Warren  De  La  Rue.  The  telescope 
grasped  the  whole  of  the  sun,  and  a  considerable  portion 
of  the  space  surrounding  it.  But  it  would  not  take  in  the 
extreme  limits  of  the  corona.  For  this  I  had  lashed  on  to 
the  large  telescope  a  light  but  powerful  instrument,  con- 
structed by  Ross,  and  lent  to  me  by  Mr.  Huggins.  I  was 
also  furnished  with  an  excellent  binocular  by  Mr.  Dallmeyer. 
In  fact,  no  man  could  have  been  more  efficiently  supported. 
It  required  a  strict  parceling  out  of  the  interval  of  totality 
to  embrace  in  it  the  entire  series  of  observations.  These, 
while  the  sun  remained  visible,  were,  to  be  made  with  an 
unsilvered  diagonal  eye-piece,  which  reflected  but  a  small 
fraction  of  the  sun's  light,  this  fraction  being  still  further 
toned  down  by  a  dark  glass.  At  the  moment  of  totality 
the  dark  glass  was  to  be  removed,  and  a  silver  reflector 
pushed  in,  so  as  to  get  the  maximum  of  light  from  the 
corona  and  prominences.  The  time  of  totality  was  dis- 
tributed as  follows: 

1.  Observe  approach  of  shadow  through  the  air:  totality. 

2.  Telescope     ...  30  seconds. 


3.  Finder 

4.  Double  image  prism 

5.  Naked  eye  . 

6.  Finder  or  binocular 

7.  Telescope     . 

8.  Observe  retreat  of  shadow. 


30  seconds. 
15  seconds. 
10  seconds. 
20  seconds. 
20  seconds. 


In  our  rehearsals  Elliot  stood  beside  me,  watch  in  hand, 
and  furnished  with  a  lantern.  He  called  out  at  the  end  of 
each  interval,  while  I  moved  from  telescope  to  finder,  from 
finder  to  polariscope,  from  polariscope  to  naked  eye,  from 
naked  eye  back  to  finder,  from  finder  to  telescope,  aban- 
doning the  instrument  finally  to  observe  the  retreating 
shadow.  All  this  we  went  over  twenty  times,  while  look- 
ing at  the  actual  sun,  and  keeping  him  in  the  middle  of 
the  field.  It  was  my  object  to  render  the  repetition  of  the 
lesson  so  mechanical  as  to  leave  no  room  for  flurry,  forget- 
fulness,  or  excitement.  Volition  was  not  to  be  called  upon, 
nor  judgment  exercised,  but  a  well-beaten  path  of  routine 
was  to  be  followed.  Had  the  opportunity  occurred,  I 
think  the  programme  would  have  been  strictly  carried 
out. 


VOYAGE  TO  ALGERIA.  119 

But  the  opportunity  did  not  occur.  For  several  days 
the  weather  had  been  ill-natured.  We  had  wind  so  strong 
as  to  render  the  hawsers  at  the  stern  of  the  Urgent  as  rigid 
as  iron,  and  to  destroy  the  navigating  lieutenant's  sleep. 
We  had  clouds,  a  thunder-storm,  and  some  rain.  Still  the 
hope  was  held  out  that  the  atmosphere  would  cleanse  itself, 
and  if  it  did  we  were  promised  air  of  extraordinary  limpid- 
ity. Early  on  the  22d  we  were  all  at  our  posts.  Spaces 
of  blue  in  the  early  morning  gave  us  some  encouragement, 
but  all  depended  on  the  relation  of  these  spaces  to  the  sur- 
rounding clouds.  Which  of  them  were  to  grow  as  the  day 
advanced?  The  wind  was  high,  and  to  secure  the  steadiness 
of  my  instrument  I  was  forced  to  retreat  behind  a  projection 
of  the  bastionet,  place  stones  upon  its  stand,  and,  further, 
to  avail  myself  of  the  shelter  of  a  sail.  My  practiced  men 
fastened  the  sail  at  the  top,  and  loaded  it  with  boulders  at 
the  bottom.  It  was  tried  severely,  but  it  stood  firm. 

The  clouds  and  blue  spaces  fought  for  a  time  with  vary- 
ing  success.  The  sun  was  hidden  and  revealed  at  intervals, 
hope  oscillating  in  sync]rr_onism  with  the  changes  of  the  sky. 
At  the  moment  of  first  contact  a  dense  cloud  intervened; 
but  a  minute  or  two  afterward  the  cloud  had  passed,  and 
the  encroachment  of  the  black  body  of  the  moon  was 
evident  upon  the  solardisk.  The  moon  marched  onward, 
and  I  saw  it  at  frequent  intervals;  a  large  group  of  spots 
were  approached  and  swallowed  up.  Subsequently  I  caught 
sight  of  the  lunar  limb  as  it  cut  through  the  middle  of  a 
large  spot.  The  spot  was  not  to  be  distinguished  from  the 
moon,  but  rose  like  a  mountain  above  it.  The  clouds, 
when  thin,  could  be  seen  as  gray  scud  drifting  across  the 
black  surface  of  the  moon;  but  they  thickened  more  and 
more,  and  made  the  intervals  of  clearness  scantier.  Dur- 
ing these  moments  I  watched  with  an  interest  bordering 
upon  fascination  the  march  of  the  silver  sickle  of  the  sun 
across  the  field  of  the  telescope.  It  was  so  sharp  and 
so  beautiful.  No  trace  of  the  lunar  limb  could  be 
observed  beyond  the  sun's  boundary.  Here,  indeed,  it 
could  only  be  relieved  by  the  corona,  which  was  utterly 
cut  off  by  the  dark  glass.  The  blackness  of  the  moon  be- 
yond the  sun  was,  in  fact,  confounded  with  the  blackness 
of  space. 

Beside  me  was  Elliot  with  the  watch  and  lantern,  while 
Lieutenant  Archer,  of  the  Royal  Engineers,  had  the  kind- 


120  FRAGMENTS  OF  SCIENCE. 

ness  to  take  charge  of  my  notebook.  I  mentioned,  and  he 
wrote  rapidly  down,  such  things  as  seemed  worthy  of 
remembrance.  Thus  my  hands  and  mind  were  entirely 
free;  but  it  was  all  to  no  purpose.  A  patch  of  sunlight  fell 
and  rested  upon  the  landscape  some  miles  awav.  It  was 
the  only  illuminated  spot  within  view.  But  to  the  north- 
west there  was  still  a  space  of  blue  which  might  reach  us  in 
time.  Within  seven  minutes  of  totality  another  space 
toward  the  zenith  became  very  dark.  The  atmosphere  was, 
as  it  were,  on  the  brink  of  a  precipice,  being  charged  with 
humidity,  which  required  but  a  slight  chill  to  bring  it 
down  in  clouds.  This  was  furnished  by  the  withdrawal  of 
the  solar  beams:  the  clouds  did  come  down,  covering  up 
the  space  of  blue  on  which  our  hopes  had  so  long  rested.  I 
abandoned  the  telescope  and  walked  to  and  fro  in  despair. 
As  the  moment  of  totality  approached,  the  descent  toward 
darkness  was  as  obvious  as  a  falling  stone.  I  looked  toward 
a  distant  ridge,  where  the  darkness  would  first  appear.  At 
the  moment  a  fan  of  beams,  issuing  from  the  hidden  sun, 
was  spread  out  over  the  southern  heavens.  Those  beams  are 
bars  of  alternate  light  and  shade,  produced  in  illuminated 
haze  by  the  shadows  of  floating  cloudlets  of  varying  density. 
The  beams  are  practically  parallel,  but  by  an  effect  of  per- 
spective they  appear  divergent,  having  the  sun,  in  fact,  for 
their  point  of  convergence.  The  darkness  took  possession 
of  the  ridge  referred  to,  lowered  upon  M.  Janssen's  observ- 
atory, passed  over  the  southern  heavens,  blotting  out  the 
beams  as  if  a  sponge  had  been  drawn  across  them.  It  then 
took  successive  possession  of  three  spaces  of  blue  sky  in  the 
southeastern  atmosphere.  I  again  looked  toward  the  ridge. 
A  glimmer  as  of  day-dawn  was  behind  it,  and  immediately 
afterward  the  fan  of  beams,  which  had  been  for  more  than 
two  minutes  absent,  revived.  The  eclipse  of  1870  had 
ended,  and,  as  far  as  the  corona  and  flames  were  concerned, 
we  had  been  defeated. 

Even  in  the  heart  of  the  eclipse  the  darkness  was  by  no 
means  perfect.  Small  print  could  be  read.  In  fact,  the 
clouds  which  rendered  the  day  a  dark  one,  by  scattering 
light  into  the  shadow,  rendered  the  darkness  less  intense 
than  it  would  have  been  had  the  atmosphere  been  without 
cloud.  In  the  more  open  spaces  I  sought  for  stars,  but 
could  find  none.  There  was  a  lull  in  the  wind  before  and 
after  totality,  but  during  the  totality  the  wind  was  strong, 


VOYAGE  TO  ALGERIA.  121 

I  waited  for  some  time  on  the  bastionet,   hoping  to  get  a 
glimpse  of  the  moon  on  the  opposite   border  of  the  sun, 
but  in  vain.     The  clouds  continued,   and  some  rain  fell.       n 
The   day    brightened    somewhat    afterward,    and,    having 
packed  all  up,  in  the  sober  twilight  Mr.    Crookes  and  my- 
self  climbed    the    heights   abtrve   the  fort  of  Vera  Cruz.        j.  . 
From  this  eminence  we  had  a  very  noble  view  over  the   +&~ 
Mediterranean  and  the  flanking  African"~trills.     The  sunset 
was  remarkable,  and  the  whole  outlook  exceedingly  fine. 

The" able  and  well-instructed  medicat"officer  of  the 
Urgent,  Mr.  Goodman,  observed  the  following  temper- 
atures during  the  progress  of  the  eclipse: 

Hour  Deg.  Hour  Deg. 

11.45  56  12.43        .  51 


11.55 
12.10 
12.37 
12.39 


55  1.5 

54  1.27 

53  1.44 

52  2.10 


The  minimum  temperature  occurred  some  minutes  after 
totality,  when  a  slight  rain  fell. 

The  wind  was  so  strong  on  the  23d  that  Captain 
Henderson  would  not  venture  out.  Guided  by  Mr.  Good- 
man, I  visited  a  cave  in  a  remarkable  stratum  of  shell- 
breccia,  and,  thanks  to  my  guide,  secured  specimens. 
Mr.  Busk  informs  me  that  a  precisely  similar  breccia  is 
found  at  Gibraltar,  at  approximately  the  same  level. 
During  the  afternoon,  Admiral  Ommaney  and  myself 
drove  to  the  fort  of  Marsa  el  Kibir.  The  fortification  is 
of  ancient  origin,  the  Moorish  arches  being  still  there  in 
decay,  but  the  fort  is  now  very  strong.  About  four  or  five 
hundred  fine-looking  dragoons  were  looking  after  their 
horses,  waiting  for  a  lull  to  enable  them  to  embark  for 
France.  One  of  their  officers  was  wandering  in  a  very 
solitary  fashion  over  the  fort.  We  had  some  conversation 
with  him.  He  had  been  at  Sedan,  had  been  taken  prisoner, 
but  had  effected  his  escape.  He  shook  his  head  when  we 
spoke  of  the  termination  of  the  war,  and  predicted  its  long 
continuance.  There  was  bitterness  in  his  tone  as  he  spoke 
of  the  charges  of  treason  so  lightly  leveled  against  French 
commanders.  The  green  waves  raved  round  the  prom- 
ontory on  which  the  fort  stands,  smiting  the  rocks, 
breaking  into  foam,  and  jumping,  after  impact,  to  a 


122  FRAGMENTS  OF  SCIENCE. 

height  of  a  hundred  feet  and  more  into  the  air.  As 
we  returned  our  vehicle  broke  down  through  the  loss  of  a 
wheel.  The  admiral  went  on  board,  while  I  remained 
long  watching  the  agitated  sea.  The  little  horses  of  Oran 
well  merit  a  passing  word.  Their  speed  and  endurance, 
both  of  which  are  heavily  drawn  upon  by  their  drivers,  are 
extraordinary. 

The  wind  sinking,  we  lifted  anchor  on  the  24th.  For 
some  hours  we  went  pleasantly  along;  but  during  the  after- 
noon the  storm  revived,  and  it  blew  heavily  against  us  all 
the  night.  When  we  came  opposite  the  bay  of  Almeria, 
on  the  25th,  the  captain  turned  the  ship,  and  steered  into 
the  bay,  where,  under  the  shadow  of  the  Sierra  Nevada, 
we  passed  Christmas  night  in  peace.  Next  morning  "a 
rose  of  dawn"  rested  on  the  snows  of  the  adjacent  moun- 
tains, while  a  purple  haze  was  spread  over  the  lower  hills. 
I  had  no  notion  that  Spain  possessed  so  fine  a  range  of 
mountains  as  the  Sierra  Nevada.  The  height  is  consid- 
erable, but  the  form  also  is  such  as  to  get  the  maximum  of 
grandeur  out  of  the  height.  We  weighed  anchor  at  eight 
A.M.,  passing  for  a  time  through  shoal  water,  the  bottom 
having  been  evidently  stirred  up.  The  adjacent  land 
seemed  eroded  in  a  remarkable  manner.  It  has  its  floods, 
which  excavate  these  valleys  and  ravines,  and  leave  those 
singular  ridges  behind.  Toward  evening  I  climbed  the 
mainmast,  and,  standing  on  the  cross-trees,  saw  the  sun  set 
amid  a  blaze  of  tiery  clouds.  The  wind  was  strong  and 
bitterly  cold,  and  I  was  glad  to  slide  back  to  the  deck  along 
a  rope,  which  stretched  from  the  mast-head  to  the  ship's 
side.  That  night  we  cast  anchor  beside  the  mole  of  Gib- 
raltar. 

On  the  morning  of  the  27th,  in  company  with  two 
friends,  I  drove  to  the  Spanish  lines,  with  the  view  of 
seeing  the  rock  from  that  side.  It  is  an  exceedingly  noble 
mass.  The  Peninsular  and  Oriental  mail-boat  had  been 
signaled  and  had  come.  Heavy  duties  called  me  home- 
vvard,  and  by  transferring  myself  from  the  Urgent  to 
the  mail-steamer  I  should  gain  three  days.  I  hired  a  boat, 
rowed  to  the  steamer,  learned  that  she  was  to  start  at  one, 
and  returned  with  all  speed  to  the  Urgent.  Making 
known  to  Captain  Henderson  my  wish  to  get  away,  he  ex- 
pressed doubts  as  to  the  possibility  of  reaching  the  mail- 
steamer  in  time.  With  his  accustomed  kindness,  he  how- 


VOYAGE  TO  ALGERIA.  123 

ever  placed  a  boat  at  my  disposal.  Four  hardy  fellows 
and  one  of  the  ship's  officers  jumped  into  it;  my  luggage, 
hastily  thrown  together,  was  tumbled  in,  and  we  were  im- 
mediately on  our  way.  We  had  nearly  four  miles  to  row- 
in  about  twenty  minutes;  but  we  hoped  the  mail-boat 
might  not  be  punctual.  For  a  time  we  watched  her 
anxiously;  there  was  no  motion;  we  came  nearer,  but  the 
flags  were  not  yet  hauled  in.  The  men  put  forth  all 
their  strength,  animated  by  the  exhortations  of  the  officer 
at  the  helm.  The  roughness  of  the  sea  rendered  their 
efforts  to  some  extent  nugatory:  still  we  were  rapidly 
approaching  the  steamer.  At- length  she  moved,  punctual 
almost  to  the  minute,  at  first  slowly,  but  soon  with  quick- 
ened pace.  We  turned  to  the  left,  so  as  to  cut  across  her 
bows.  Five  minutes'  pull  would  have  brought  us  up  to 
her.  The  officer  waved  his  cap  and  I  my  hat.  "If  they 
could  only  see  us,  they  might  back  to  us  in  a  moment." 
But  they  did  not  see  us,  or  if  they  did,  they  paid  us  no  at- 
tention. I  returned  to  the  Urgent,  discomfited,  but 
grateful  to  the  fine  fellows  who  had  wrought  so  hard  to 
carry  out  my  wishes. 

Glad  of  the  quiet,  in  the  Sflher  afternoon  I  took  a  walk 
toward  Europa  Point.  The  sky  darkened  and  heavy  squalls 
passed  at  intervals.  Private  theatricals  were  at  the  Con- 
vent, and  the  kind  and  courteous  governor  had  sent  cards  to 
the  eclipse  party.  I  failed  in  my  duty  in  not  going.  St. 
Michael's  Cave  is  said  to  rival,  if  it  does  not  outrival,  the 
Mammoth  Cave  of  Kentucky.  On  the  28th  Mr.  Crookes,  Mr. 
Carpenter,  and  myself,  guided  by  a  military  policeman  who 
understood  his  work,  explored  the  cavern.  The  mouth  is 
about  1,100  feet  above  the  sea.  We  zigzagged  up  to  it, 
and  first  were  led  into  an  aperture  in  the  rock,  at  some 
height  above  the  true  entrance  of  the  cave.  In  this  upper 
cavern  we  saw  some  tall  and  beautiful  stalactite  pillars. 

The  water  drips  from  the  roof  charged  with  bicarbonate 
of  lime.  Exposed  to  the  air,  the  carbonic  acid  partially 
escapes,  and  the  simple  carbonate  of  lime,  which  is  hardly 
at  all  soluble  in  water,  deposits  itself  as  a  solid,  forming 
stalactites  and  stalagmites.  Even  the  exposure  of  chalk 
or  limestone  water  to  the  open  air  partially  softens  it.  A 
specimen  of  the  Redbourne  water  exposed  by  Professors 
Graham,  Miller,  and  Hofmann,  in  a  shallow  basin,  fell 
from  eighteen  degrees  to  nine  degrees  of  hardness.  The 


124  '  FRAGMENTS  OF  SCIENCE. 

softening  process  of  Clark  is  virtually  a  hastening  of  the 
natural  process.  Here,  however,  instead  of  being  permitted 
to  evaporate,  half  the  carbonic  acid  is  appropriated  by 
lime,  the  half  thus  taken  up,  as  well  as  the  remaining  half, 
being  precipitated.  The  solid  precipitate  is  permitted  to 
sink,  and  the  clear  supernatant  liquid  is  limpid  soft 
water. 

We  returned  to  the  real  mouth  of  St.  Michael's  Cave, 
which  is  entered  by  a  wicket.  The  floor  was  somewhat 
muddy,  and  the  roof  and  walls  were  wet.  We  soon  found 
ourselves  in  the  midst  of  a  natural  temple,  where  tall  col- 
umns sprang  complete  from  floor  to  roof ,  while  incipient 
columns  were  growing  to  meet  each  other,  upward  and 
downward.  The  water  which  trickles  from  the  stalactite, 
after  having  in  part  yielded  up  its  carbonate  of  lime,  falls 
upon  the  floor  vertically  underneath,  and  there  builds 
the  stalagmite.  Consequently,  the  pillars  grow  from 
above  and  below  simultaneously,  along  the  same  vertical. 
It  is  easy  to  distinguish  the  stalagmitic  from  the  stalac- 
titic  portion  of  the  pillars.  The  former  is  always  divided 
into  short  segments  by  protuberant  rings,  as  if  deposited 
periodically,  while  the  latter  presents  a  uniform  surface. 
In  some  cases  the  points  of  inverted  cones  of  stalactite 
rested  on  the  centers  of  pillars  of  stalagmite.  The  proc- 
ess of  solidification  and  the  consequent  architecture  were 
alike  beautiful. 

We  followed  our  guide  through  various  branches  and 
arms  of  the  cave,  climbed  and  descended  steps,  halted  at 
the  edges  of  dark  shafts  and  apertures,  and  squeezed  our- 
selves through  narrow  passages.  From  time  to  time  we 
halted,  while  Mr.  Crookes  illuminated  with  ignited  mag- 
nesium wire,  the  roof,  columns,  dependent  spears,  and 
graceful  drapery  of  the  stalactites.  Once,  coming  to  a 
magnificent  cluster  of  icicle-like  spears,  we  helped  ourselves 
to  specimens.  There  was  some  difficulty  in  detaching 
the  more  delicate  ones,  their  fragility  was  so  great.  A 
consciousness  of  vandalism,  which  smote  me  at  the  time, 
haunts  me  still;  for,  though  our  requisitions  were  moder- 
ate, this  beauty  ought  not  to  be  at  all  invaded.  Pendent 
from  the  roof,  in  their  natural  habitat,  nothing  can  exceed 
their  delicate  beauty;  they  live,  as  it  were,  surrounded  by 
organic  connections.  In  London  they  are  curious,  but 
not  beautiful.  Of  gathered  shells  Emerson  writes: 


VOYAGE  TO  ALGERIA.  125 

1  wiped  away  the  weeds  and  foam, 
And  brought  iny  sea-born  treasures  home  : 
But  the  poor,  unsightly,  noisome  things 
Had  left  their  beauty  on  the  shore, 
With  the  sun,  and  the  sand,  and  the  wild  uproar. 

The  promontory  of  Gibraltar  is  so  burrowed  with  caverns 
that  it  has  been  called  the  Hill  of  Caves.  They  are  appar- 
ently related  to  the  geologic  disturbances  which  the  rock 
has  undergone.  The  earliest  of  these  is  the  tilting  of  the 
once  horizontal  strata.  Suppose  a  force  of  torsion  to  act 
upon  the  promontory  at  its  southern  extremity  near 
Europa  Point,  and  suppose  the  rock  to  be  of  a  partially 
yielding  character;  such  a  force  would  twist  the  strata  into 
screw-surfaces,  the  greatest  amount  of  twisting  being 
endured  near  the  point  of  application  of  the  force.  Such 
a  twisting  the  rock  appears  to  have  suffered;  but  instead  of 
the  twist  fading  gradually  and  uniformly  off,  in  passing 
from  south  to  north,  the  want  of  uniformity  in  the  material 
has  produced  lines  of  dislocation  where  there  are  abrupt 
changes  in  the  amount  of  twist.  Thus,  at  the  northern 
end  of  the  rock  the  dip  to  the  west  is  nineteen  degrees;  in 
the  Middle  Hill,  it  is  thirty-eight  degrees;  in  the  center  of 
the  South  hill,  or  Sugar  Loaf,  it  is  fifty-seven  degrees.  At 
the  southern  extremity  of  the  Sugar  Loaf  the  strata  are 
vertical,  while  farther  to  the  south  they  actually  turn  over 
and  dip  to  the  east. 

The  rock  is  thus  divided  into  three  sections,  separated 
from  each  other  by  places  of  dislocation,  where  the  strata 
are  much  wrenched  and  broken.  These  are  called  the 
Northern  and  Southern  Quebrada,  from  the  Spanish 
"  Tierra  Quebrada,"  or  broken  ground.  It  is  at  these 
places  that  the  inland  caves  of  Gibraltar  are  almost  ex- 
clusively found.  Based  on  the  observations  of  Dr.  Falconer 
and  himself,  an  excellent  and  most  interesting  account  of 
these  caves,  and  of  the  human  remains  and  works  of  art 
which  they  contain,  was  communicated  by  Mr.  Busk  to 
the  meeting  of  the  Congress  of  Prehistoric  Archaeology  at 
Norwich,  and  afterward  printed  in  the  "  Transactions"  of 
the  Congress.*  Long  subsequent  to  the  operation  of  the 

*  In  this  essay  Mr.  Busk  refers  to  the  previous  labors  of  Mr.  Smith, 
of  Jordan  Hill,  to  whom  we  owe  most  of  our  knowledge  of  the  geology 
of  the  rock. 


12Q  FRAGMENTS  OF  SV1KNCE. 

twisting  force  just  referred  to,  the  promontory  under- 
went various  changes  of  level.  There  are  sea-terraces 
and  layers  of  shell-breccia  along  its  flanks,  and  numerous 
caves  which,  unlike  the  inland  ones,  are  the  product 
of  marine  erosion.  The  Ape's  Hill,  on  the  African  side 
of  the  strait,  Mr.  Busk  informs  me,  has  undergone  similar 
disturbances.* 

In  the  harbor  of  Gibraltar,  on  the  morning  of  our 
departure,  I  resumed  a  series  of  observations  on  the  color 
of  the  sea.  On  the  way  out  a  number  of  specimens  had 
been  collected,  with  a  view  to  subsequent  examination. 
But  the  bottles  were  claret  bottles,  of  doubtful  purity.  At 
Gibraltar,  therefore,  I  purchased  fifteen  white  glass  bottles, 
with  ground  glass  stoppers,  and  at  Cadiz,  thanks  to  the 
friendly  guidance  of  Mr.  Cameron,  I  secured  a  dozen  more. 
These  seven-aud-twenty  bottles  were  filled  with  water, 
taken  at  different  places  between  Oran  and  Spithead. 

And  here  let  rne  express  my  warmest  acknowledgments 
to  Captain  Henderson,  the  commander  of  H.M.S.  Urgent, 
who  aided  me  in  my  observations  in  every  possible  way. 
Indeed,  my  thanks  are  due  to  all  the  officers  for  their  un- 
failing courtesy  and  help.  The  captain  placed  at  my  dis- 
posal his  own  cockswain,  an  intelligent  fellow  named 
Thorogood,  who  skillfully  attached  a  cord  to  each  bottle, 
weighted  it  with  lead,  cast  it  into  the  sea,  and,  after  three 
successive  rinsings,  filled  it  under  my  eyes.  The  contact  of 
jugs,  buckets,  or  other  vessels  was  thus  avoided;  and  even 
the  necessity  of  pouring  out  the  water,  afterward,  through 
the  dirty  London  air. 

The  mode  of  examination  applied  to  these  bottles  has 
been  already  described.!  The  liquid  is  illuminated  by  a 
powerfully  condensed  beam,  its  condition  being  revealed 
through  the  light  scattered  by  its  suspended  particles. 
"  Care  is  taken  to  defend  the  eye  from  the  access  of  all 
other  light,  and,  thus  defended,  it  becomes  an  organ  of 
inconceivable  delicacy."  Were  water  of  uniform  density 
perfectly  free  from  suspended  matter,  it  would,  in  my 

*  No  one  can  rise  from  the  perusal  of  Mr.  Busk's  paper  without 
a  feeling  of  admiration  for  the  principal  discoverer  and  indefa- 
tigable explorer  of  the  Gibraltar  caves,  tlie  late  Captain  Frederick 
Brome. 

f  "  Floating  Matter  of  the  Air,"  Art.   "  Dust  and  Disease." 


VOYAGE  TO  ALGERIA.  127 

opinion,  scatter  no  light  at  all.  The  track  of  a  luminous 
beam  could  not  be  seen  in  such  water.  But  "an  amount 
of  impurity  so  infinitesimal  as  to  be  scarcely  expressible  in 
numbers,  and  the  individual  particles  of  which  are  so  small 
as  wholly  to  elude  the  microscope,  may,  when  examined  by 
the  method  alluded  to,  produce  not  only  sensible,  but  strik- 
ing effects  upon  the  eye." 

The  result  of  the  examination  of  nineteen  bottles  filled 
at  various  places  between  Gibraltar  and  Spithead,  are 
here  tabulated: 


1  Gibraltar  Harbor Green Thick  with  fine  particles 

a  Two  miles  from  Gibraltar ....  Clearer  green Thick  with  very  fine  particles 

3  Off  Cabreta  Point Bright  green Still  thick,  but  less  so 

4  Off  Cabreta  Point Black-indigo  Much  less  thick,  very  pure 

5  Off    Tarifa Undecided Thicker  than  No.  4 

6  Beyond  Tarifa Cobalt-blue Much  purer  than  No.  5 

7  Twelve  miles  from  Cadiz Yellow-green Very  thick 

8  Cadiz  Harbor Yellow-green Exceedingly  thick 

9  Fourteen  miles  from  Cadiz. .  .Yellow-green. .   .  .Thick,  but  less  so 

10  Fourteen  miles  from  Cadiz. .  Bright  green.. 

11  Between  Capes  St.  Mary  and 


Vincent Deep  indigo. . 

12    Off  the  Burlings Strong  green . 

"    Beyond  the  Burlings Indigo 


..Much  less  thick 

.  .Very  little  matter,  very  pure 
.  .Thick,  with  fine  matter 
.  .Very  little  matter,  pure 


pill' 

•  litt 


14  Off  Cape  Finisterre Undecided. . . . 

15  Bay  of  Biscay Black-indigo  . .   .  .Very  little  matter,  very  pure 

16  Bay  of  Biscay Indigo Very  fine  matter.    Iridescent 

17  Off  Ushant Dark  green A  good  deal  of  matter 

18  Off  St.  Catherine's Yellow-green Exceedingly  thick 

19  Spithead Green Exceedingly  thick 

Here  we  have  three  specimens  of  water,  described  as 
green,  a  clearer  green,  and  bright  green,  taken  in  Gibraltar 
harbor,  at  a  point  two  miles  from  the  harbor,  and  off 
Cabreta  Point.  The  home  examination  showed  the  first 
to  be  thick  with  suspended  matter,  the  second  less  thick, 
and  the  third  still  less  thick.  Thus  the  green  brightened 
as  the  suspended  matter  diminished  in  amount. 

Previous  to  the  fourth  observation  our  excellent  navigat- 
ing lieutenant,  Mr.  Brown,  steered  along  the  coast,  thus 
avoiding  the  adverse  current  which  sets  in,  through  the 
strait,  from  the  Atlantic  to  the  Mediterranean.  He  was  at 
length  forced  to  cross  the  boundary  of  the  Atlantic  current, 
which  was  defined  with  extraordinary  sharpness.  On  the 
one  side  of  it  the  water  was  a  vivid  green,  on  the  other  a 
deep  blue.  Standing  at  the  bow  of  the  ship,  a  bottle 'could 
be  filled  with  blue  water,  while  at  the  same  moment  a 
bottle  cast  from  the  stern  could  be  filled  with  green  water. 


128  FRAGMENTS  OF  SCIENCE. 

Two  bottles  were  secured,  one  on  each  side  of  this  remark- 
able boundary.  In  the  distance  the  Atlantic  had  the  hue 
called  ultra-marine;  but  looked  fairly  down  upon,  it  was 
of  almost  inky  blackness — black  qualified  by  a  trace  of 
indigo. 

What  change  does  the  home  examination  here  reveal? 
In  passing  to  indigo,  the  water  becomes  suddenly  augmented 
in  purity,  the  suspended  matter  becoming  suddenly  less. 
Off  Tarifa,  the  deep  indigo  disappears,  and  the  sea  is  un- 
decided in  color.  Accompanying  this  change,  we  have  a 
rise  in  the  quantity  of  suspended  matter.  Beyond  Tarifa, 
we  change  to  cobalt-blue,  the  suspended  matter  falling  at 


the  same  time  in  quantity.     This  water  is  distinctly  purer 

i.     We  approach 
from  the  city  get  into  yellow-green  water;  this  the  London 


than    the  green.     We  approach  Cadiz,  and  at  twelve  miles 


examination  shows  to  be  thick  with  suspended  matter. 
The  same  is  true  of  Cadiz  harbor,  and  also  of  a  point 
fourteen  miles  from  Cadiz  in  the  homeward  direction. 
Here  there  is  a  sudden  change  from  yellow-green  to  a 
bright  emerald-green,  and  accompanying  the  change 
a  sudden  fall  in  the  quantity  of  suspended  matter. 
Between  Cape  St.  Mary  and  Cape  St.  Vincent  the 
water  changes  to  the  deepest  indigo,  a  further  diminution 
of  the  suspended  matter  being  the  concomitant  phenom- 
enon. 

We  now  reach  the  remarkable  group  of  rocks  called  the 
Burlings,  and  find  the  water  between  the  shore  and  the 
rocks  a  strong  green;  the  home  examination  shows  it  to  be 
thick  with  fine  matter.  Fifteen  or  twenty  miles  beyond 
the  Burlings  we  come  again  into  indigo  water,  from  which 
the  suspended  matter  has  in  great  part  disappeared.  Off 
Cape  Finisterre,  about  the  place  where  the  Captain  went 
down,  the  water  becomes  green,  and  the  home  examination 
pronounces  it  to  be  thicker.  Then  we  enter  the  bay  of 
Biscay,  where  the  indigo  resumes  its  power,  and  where  the 
home  examination  shows  the  greatly  augmented  purity  of 
the  water.  A  second  specimen  of  water,  taken  from  the 
bay  of  Biscay,  held  in  suspension  fine  particles  of  a  peculiar 
kind;  the  size  of  them  was  such  as  to  render  the  water 
richly  iridescent.  It  showed  itself  green,  blue,  or  salmon- 
colored,  according  to  the  direction  of  the  line  of  vision. 
Finally,  we  come  to  our  last  two  bottles,  the  one  taken 
opposite  St.  Catherine's  lighthouse,  in  the  Isle  of  Wight, 


VOYAGE  TO  ALGERIA.  129 

the  other  at  Spithead.  The  sea  at  both  these  places  was 
green,  and  both  specimens,  as  might  be  expected,  were 
pronounced  by  the  home  examination  to  be  thick  with 
suspended  matter. 

Two  distinct  series  of  observations  are  here  referred  to — 
the  one  consisting  of  direct  observations  of  the  color  of 
the  sea,  conducted  during  the  voyage  from  Gibraltar  to 
Portsmouth:  the  other  carried  out  in  the  laboratory  of  the 
Royal  Institution.  And  here  it  is  to  be  noted  that  in  the 
home  examination  I  never  knew  what  water  was  placed  in 
my  hands.  The  labels,  with  the  names  of  the  localities 
written  upon  them,  had  been  tied  up,  all  information 
regarding  the  source  of  the  water  being  thus  held  back. 
The  bottles  were  simply  numbered,  and  not  till  all  of  them 
had  been  examined,  and  described,  were  the  labels  opened, 
and  the  locality  arid  sea-color  corresponding  to  the  various 
specimens  ascertained.  The  home  observations,  there- 
fore, must  have  been  perfectly  unbiased,  and  they  clearly 
establish  the  association  of  the  green  color  with  fine  sus- 
pended matter,  and  of  the  ultramarine  color,  and  more 
especially  of  the  black-indigo  hue  of  the  Atlantic,  with  the 
comparative  absence  of  such  matter. 

So  much  for  mere  observation;  but  what  is  the  cause  of 
the  dark  hue  of  the  deep  ocean?*  A  preliminary  remark 
or  two  will  clear  our  way  toward  an  explanation.  Color 
resides  in  white  light,  appearing  when  any  constituent  of 
the  white  light  is  withdrawn.  The  hue  of  a  purple  liquid, 
for  example,  is  immediately  accounted  for  by  its  action  on 
a  spectrum.  It  cuts  out  the  yellow  and  green,  and  allows 
the  red  and  blue  to  pass  through.  The  blending  of 
these  two  colors  produces  the  purple.  But  while  such 
a  liquid  attacks  with  special  energy  the  vellow  and  green, 
it  enfeebles  the  whole  spectrum.  By  increasing  the 
thickness  of  the  stratum  we  may  absorb  the  whole  of  the 
light.  The  color  of  a  blue  liquid  is  similarly  accounted 
for.  It  first  extinguished  the  red;  then,  as  the  thick- 

*  A  note,  written  to  me  on  October  22,  by  my  friend  Canon  Kings- 
ley,  contains  the  following  reference  to  this  point:  "  I  have  never 
seen  the  lake  of  Geneva,  but  I  thought  of  the  brilliant,  dazzling  dark 
blue  of  the  mid  Atlantic  under  the  sunlight,  and  its  black- blue  under 
cloud,  both  so  solid  that  one  might  leap  off  the  sponson  on  to  it  with- 
out fear;  this  was  to  me  the  most  wonderful  thing  which  I  saw  on, 
my  voyages  to  and  from  the  West  Indies." 


]  30  FRA  GMENTS  OF  SCIENCE. 

ness  augments,  it  attacks  the  orange,  yellow,  and  green 
in  succession;  the  blue  alone  finally  remaining.  But 
even  it  might  be  extinguished  by  a  sufficient  depth  of  the 
liquid. 

And  now  we  are  prepared  for  a  brief,  but  tolerably  com- 
plete, statement  of  that  action  of  sea-water  upon  light,  to 
which  it  owes  its  darkness.  The  spectrum  embraces  three 
classes  of  rays — the  thermal,  the  visual,  and  the  chemical. 
These  divisions  overlap  each  other;  the  thermal  rays  are  in 
part  visual,  the  visual  rays  in  part  chemical,  and  vice  versa. 
The  vast  body  of  thermal  rays  lie  beyond  the  red,  being 
invisible.  These  rays  are  attacked  with  exceeding-  energy 
by  water.  They  are  absorbed  close  to  the  surface  of  the 
sea,  and  are  the  great  agents  in  evaporation.  At  the  same 
time  the  whole  spectrum  suffers  enfeeblement;  water 
attacks  all  its  ravs,  but  with  different  degrees  of  energy. 
Of  the  visual  rays,  the  red  are  first  extinguished.  As  the 
solar  beam  plunges  deeper  into  the  sea,  orange  follows  red, 
yellows  follows  orange,  green  follows  yellow,  and  the 
various  shades  of  blue,  where  the  water  is  deep  enough, 
follow  green.  Absolute  extinction  of  the  solar  beam 
would  be  the  consequence  if  the  water  were  deep  and 
uniform.  If  it  contained  no  suspended  matter,  such 
water  would  be  as  black  as  ink.  A  reflected  glimmer  of 
ordinary  light  would  reach  us  from  its  surface,  as  it  would 
from  the  surface  of  actual  ink;  but  no  light,  hence  no 
color,  would  reach  us  from  the  body  of  the  water. 

In  very  clear  and  deep  sea-water  this  condition  is 
approximately  fulfilled,  and  hence  the  extraordinary  dark- 
ness of  such  water.  The  indigo,  already  referred  to,  is,  I 
believe,  to  be  ascribed  in  part  to  the  suspended  matter, 
which  is  never  absent,  even  in  the  purest  natural  water; 
and  in  part  to  the  slight  reflection  of  the  light  from  the 
limiting  surfaces  of  strata  of  different  densities.  A  modi- 
cum of  light  is  thus  thrown  back  to  the  eye,  before  the 
depth  necessary  to  absolute  extinction  has  been  attained. 
An  effect  precisely  similar  occurs  under  the  moraines  of 
glaciers.  The  ice  here  is  exceptionally  compact,  and, 
owing  to  the  absence  of  the  internal  scattering  common  in 
bubbled  ice,  the  light  plunges  into  the  mass,  where  it  is 
extinguished,  the  perfectly  clear  ice  presenting  an  appear- 
ance of  pitchy  blackness.* 

*  I  learn  from  a  correspondent  tbat  certain  Welsh  tarns,  which  are 
reputed  bottomless,  have  this  inky  hue. 


VOYAGE  TO  ALGERIA.  131 

The  green  color  of  the  sea  has  now  to  be  accounted  for; 
and  here,  again,  let  us  fall  back  upon  the  sure  basis  of  ex- 
periment. A  strong  white  dinner-plate  had  a  lead  weight 
securely  fastened  to  it.  Fifty  or  sixty  yards  of  strong 
hempen  line  were  attached  to  the  plate.  My  assistant, 
Thorogood,  occupied  a  boat,  fastened  as  usual  to  the  davits 
of  the  Urgent,  while  I  occupied  a  second  boat  nearer  the 
stern  of  the  ship.  He  cast  the  plate  as  a  mariner  heaves 
the  lead,  and  by  the  time  it  reached  me  it  had  sunk  a  con- 
siderable depth  in  the  water.  In  all  cases  the  hue  of  this 
plate  was  green.  Even  when  the  sea  was  of  the  darkest 
indigo,  the  green  was  vivid  and  pronounced.  I  could 
notice  the  gradual  deepening  of  the  color  as  the  plate  sank, 
but  at  its  greatest  depth,  even  in  indigo  water,  the  color  was 
still  a  blue-green.* 

Other  observations  confirmed  this  one.  The  Urgent  is  a 
screw  steamer,  and  right  over  the  blades  of  the  screw  was 
an  orifice  called  the  screw-well  through  which  one  could 
look  from  the  pjoop  down  upon  the  screw.  The  surface- 
glimmer,  which  so  pesters  the  eye,  was  here  in  a  great 
measure  removed.  Midway  down,  a  plank  crossed  the 
screw-well  from  side  to  side;  on  this  I  placed  myself  and 
observed  the  action  of  the  screw  underneath.  The  eye  was 
rendered  sensitive  by  the  moderation  of  the  light;  and,  to 
remove  still  furtherall  disturbing  causes,  Lieutenant  Walton 
had  a  sail  and  tarpaulin  thrown  over  the  mouth  of  the  well. 
Underneath  this  I  perched  myself  on  the  plank  and 
watched  the  screw.  In  an  indigo  sea  the  play  of  color  was 
indescribably  beautiful,  and  the  contrast  between  the 
water,  which  had  the  screw  blades,  and  that  which  had  the 
bottom  of  the  ocean,  as  a  background,  was  extraordinary. 
The  one  was  of  the  most  brilliant  green,  the  other  of  the 
deepest  ultramarine.  The  surface  of  the  water  above  the 
screw-blade  was  always  ruffled.  Liquid  lenses  were  thus 
formed,  by  which  the  colored  light  was  withdrawn  from 
some  places  and  concentrated  upon  others,  the  water  flash- 
ing with  metallic  luster.  The  screw-blades  in  this  case 
played  the  part  of  the  dinner-plate  in  the  former  case,  and 
there  were  other  instances  of  a  similar  kind.  The  white 
bellies  of  porpoises  showed  the  green  hue,  varying  in  inten- 

*  In  no  case,  of  course,  is  the  green  pure,  but  a  mixture  of  green 
and  blue. 


132  FRAGMENTS  OF  SCIENCE. 

sity  as  the  creatures  swung  to  and  fro  between  the  surface 
and  the  deeper  water.  Foam,  at  a  certain  depth  below 
the  surface,  was  also  green.  In  a  rough  sea  the  light 
which  penetrated  the  summit  of  a  wave  sometimes 
reached  the  eye,  a  beautiful  green  cap  being  thus  placed 
upon  the  wave,  even  in  indigo  water. 

But  how  is  this  color  to  be  connected  with  the  suspended 
particles?  Thus.  Take  the  dinner-plate  which  showed  so 
brilliant  a  green  when  thrown  into  indigo  water.  Suppose 
it  to  diminish  in  size,  until  it  reaches  an  almost  micro- 
scopic magnitude.  It  would  still  behave  substantially  as 
the  larger  plate,  sending  to  the  eye  its  modicum  of  green 
light.  If  the  plate,  instead  of  being  a  large  coherent  mass, 
were  ground  to  a  powder  sufficiently  fine,  and  in  this  con- 
dition diffused  through  the  clear  sea-water,  it  would  also 
send  green  light  to  the  eye.  In  fact,  the  suspended  par- 
ticles which  the  home  examination  reveals,  act  in  all 
essential  particulars  like  the  plate,  or  like  the  screw-blades, 
or  like  the  foam,  or  like  the  bellies  of  the  porpoises.  Thus 
I  think  the  greenness  of  the  sea  is  physically  connected 
with  the  matter  which  it  holds  in  suspension. 

We  reached  Portsmouth  on  January  5,  1871.  Then 
ended  a  voyage  which,  though  its  main  object  was  not 
realized,  has  left  behind  it  pleasant  memories,  both  of  the 
aspects  of  nature  and  the  kindliness  of  men. 


CHAPTER  VII. 

NIAGARA.* 

IT  is  one  of  the  disadvantages  of  reading  books  about 
natural  scenery  that  they  fill  the  mind  with  pictures,  often 
exaggerated,  often  distorted,  often  blurred,  and,  even 
when  well  drawn,  injurious  to  the  freshness  of  first  im- 
pressions. Such  has  been  the  fate  of  most  of  us  with  re- 
gard to  the  Falls  of  Niagara.  There  was  little  accuracy  in 
the  estimates  of  the  first  observers  of  the  cataract.  Startled 
by  an  exhibition  of  power  so  novel  and  so  grand,  emotion 

*  A  Discourse  delivered  at  the  Royal  Institution  of  Great  Britain, 
April  4,  1873. 


Sr 


NIAGARA.  13 

leaped  beyond  the  control  of  the  judgment,  and  gave  cur- 
rency to  notions  which  have  often  led  to  disappointment. 

A  record  of  a  voyage  in  1535  by  a  French  mariner  named 
Jacques  Cartier,  contains,  it  is  said,  the  first  printed  allu- 
sion to  Niagara.  In  1603  the  first  map  of  the  district 
was  constructed  by  a  Frenchman  named  Champlain.  In 
1648  the  Jesuit  Rageneau,  in  a  letter  to  his  superior  at 
Paris,mentions  Niagara  as  "  a  cataract  of  frightful  height/'* 
In  the  winter  of  1678  and  1679  the  cataract  was  visited  by 
Father  Hennepin,  and  described  in  a  book  dedicated  "  to 
the  king  of  Great  Britain."  He  gives  a  drawing  of  the 
waterfall,  which  shows  that  serious  changes  have  taken 
place  since  his  time.  He  describes  it  as  "  a  great  and  pro- 
digious cadence  of  water,  to  which  the  universe  does  not 
offer  a  parallel."  The  height  of  the  fall,  according  to 
Hennepin,  was  more  than  600  feet.  ]  "  The  waters,"  he 
says,  "  which  fall  from  this  great  precipice  do  foam  and 
boil  in  the  most  astonishing  manner,  making  a  noise  more 
terrible  than  that  of  thunder.  When  the  wind  blows  to 
the  south  its  frightful  roaring  may  be  heard  for  more  than 
fifteen  leagues."  The  Baron  la  Hontan,  who  visited  Niag- 
ara in  1687,  makes  the  height  £00  feet.  In  1721  Charle- 
vois,  in  a  letter  to  Madame  de  Maintenon,  after  referring 
to  the  exaggerations  of  his  predecessors,  thus  states  the 
result  of  his  own  observations:  "  For  my  part,  after  ex- 
amining it  on  all  sides,  I  am  inclined  to  think  that  we  can- 
not allow  it  less  than  140  or  150  feet"  —  a  remarkably 
close  estimate.  At  that  time,  viz.,  a  hundred  and  fifty 
years  ago,  it  had  the  shape  oj  a  horseshoe,  and  reasons  will 
subsequently  be  given  for  holding  that  this  has  been  always 
the  form  of  the  cataract,  from  its  origin  to  its  present 
site. 

As  regards  the  noise  of  the  fall,  Charlevois  declares  the 
accounts  of  his  predecessors,  which,  I  may  say,  are  repeated 
to  the  present  hour,  to  be  altogether  extravagant.  He  is 
perfectly  right.  The  thunders  of  Niagara  are  formidable 
enough  to  those  who  really  seek  them  at  the  base  of  the 
Horseshoe  Fall;  but  on  the  banks  of  the  river,  and  par- 
ticularly above  the  fall,  its  silence,  rather  than  its  noise, 

*  From  an  interesting  little  book  presented  to  me  at  Brooklyn  by 
its  author,  Mr.  Holly,  some  of  these  data  are  derived:  Hennepin, 
Kalm,  Bakewell,  Lyell,  Hall,  and  others  I  have  myself  consulted. 


134  FRAGMENTS  OF  SCIENCE. 

is  surprising.  This  arises,  in  part,  from  the  lack  of  reso- 
nance; the  surrounding  country  being  flat,  and  therefore 
furnishing  no  echoing  surfaces  to  reinforce  the  shock  of 
the  water.  The  resonance  from  the  surrounding  rocks 
causes  the  Swiss  Reuss  at  the  Devil's  Bridge,  when  full,  to 
thunder  more  loudly  than  the  Niagara. 

On  Friday,  November  1,  1872,  just  before  reaching  the 
village  of  Niagara  Falls,  I  caught,  from  the  railway  train, 
^_my  first  glimpse  of  the  smoke  of  the  cataract.  Immedi- 
ately after  my  arrival  I  went  with  a  friend  to  the  northern 
end  of  the  AmericanJlall.  It  may  be  that  my  mood  at  the 
time  toned  clown  the  impression  produced  by  the  first 
aspect  of  this  grand  cascade;  but  I  felt  nothing  like  disap- 
pointment, knowing,  from  old  experience,  that  time  and 
close  acquaintanceship,  the  gradual  interweaving  of  mind 
and  nature,  must  powerfully  influence  my  final  estimate  of 
the  scene.  After  dinner  we  crossed  to  Goat  Island,  and, 
turning  to  the  right,  reached  the  southern  end  of  the 
American  Fall.  The  river  is  here  studded  with  small 
islands.  Crossing  a  wooden  bridge  to  Luna  Island,  and 
clasping  a  tree  which  grows  near  its  edge,  I  looked  long  at 
the  cataract,  which  here  shoots  down  the  precipice  like  an 
avalanche  of  foam.  It  grew  in  power  and  beauty.  The  chan- 
nel spanned  by  the  wooden  bridge  was  deep,  and  the  river 
there  doubled  over  the  edge  of  the  precipice,  like  the  swell 
of  a  muscle,  unbroken.  The  ledge  here  overhangs,  the 
water  being  poured  out  far  beyond  the  base  of  the  precipice. 
A  space,  called  the  Cave  of  the  Winds,  is  thus  enclosed 
between  the  wall  of  rock  and  the  falling  water. 

Goat  Island  ends  in  a  sheer  dry  precipice,  which  con- 
nects the  American  and  Horseshoe  Falls.  Midway  between 
both  is  a  wooden  hut,  the  residence  of  the  guide  to  the 
Cave  of  the  Winds,  and  from  the  hut  a  winding  staircase, 
called  Biddle's  Stan-,  descends  to  the  base  of  the  precipice. 
On  the  evening  of  my  arrival  I  went  down  this  stair,  and 
wandered  along  the  bottom  of  the  cliff.  One  well-known 
factor  in  the  formation  and  retreat  of  the  cataract  was 
immediately  observed.  A  thick  layer  of  limestone  formed  the 
upper  portion  of  the  cliff.  This  rested  upon  a  bed  of  soft 
shale,  which  extended  round  the  base  of  the  cataract.  The 
violent  recoil  of  the  water  against  this  yielding  substance 
crumbles  it  away,  undermining  the  ledge  above,  which, 
unsupported,  eventually  breaks  off,  and  produces  the 
observed  recession. 


NIAGARA.  135 

At  the  southern  extremity  of  the  Horseshoe  is  a  promon- 
tory, formed  by  the  doubling  back  of  the  gorge  excavated 
by  the  cataract,  and  into  which  it  plunges.  On  the  prom- 
ontory stands  a  stone  building,  called  the  Terrapin 
Tower,  the  door  of  which  had  been  nailed  up  because  of 
the  decay  of  the  staircase  within  it.  Through  the  kindness 
of  Mr.  Townsend,  the  superintendent  of  Goat  Island,  the  , 
door  was  opened  for  me.  Frmii  ^thisjtower.at  all  hours  of  the 
dav,  and  at  some  hours  of  the  night,  1  watched  and  listened  - 
to  the  Horseshoe  Fall.  The  river  here  is  evidently  much 
deeper  than  the  American  branch;  and  instead  of  bursting 
into  foam  where  it  quits  the  ledge,  it  bends  solidly  over,  , 
and  falls  in  a  continuous  layer  of  the^~m<>st  vivid  green. ^  >)  3>D{ 
The  tint  is  not  uniform;  long  stripes  of  deeper  Tine  alter-/ 
Dating  with  bands  of  brighter  color.  Close  to  the  ledge 
over  which  the  water  rolls,  foam  is  generated,  the  light 
falling  upon  which,  and  flashing  back  from  it,  is  sifted 
in  its  passage  to  and  fro,  and  changed  from  white  tO'emer- 
ald-greeu.  Heaps  of  superficial  foam  are  also  formed  at 
intervals  along  the  ledge,  and  are  immediately  drawn  into 
long  white  striae.*  Lower  down,  the  surface,  shaken  by 
the  reaction  from  below,  incessantly  rustles  into  whiteness. 
The  descent  finally  resolves  itself  into  a  rhythm,  the  water 
reaching  the  bottom  of  the  fall  in  periodic  gushes.  ££or-is 
the  spray  uniformly  diffused  through  the  air,  but  is 
wafted  through  it  in  successive  veils  of  gauze-like  texture. 
From  all  this  it  is  evident  that  beauty  is  not  absent  from 
the  Horseshoe  Pall,  but  majesty  is  its  chief  attribute.  The 
plunge  of  the  water  is  not  wild,  but  deliberate,  vast  and 
fascinating.  From  the  Terrapin  Tower,  the  adjacent  arm 
of  the  Horseshoe  is  seen  projected  against  the  opposite  one, 
midway  down;  to  the  imagination,  therefore,  is  left  the 
picturing  of  the  gulf  into  which  the  cataract  plunges. 

The__JLelight  which  natural  scenery  produces  in  some 
minHs  is  difficult  to  explain,  and  the  conduct  which  it 
prompts  can  hardly  be  fairly  criticised  by  those  who  have 
never  experienced  it.  It  seems  to  me  a  deduction  from  the 
completeness  of  the  celebrated  Thomas  Young,  that  he 
was  unable  to  appreciate  natural  scenery.  "He  had 

*The  direction  of  the  wind  with  reference  to  the  course  of  a  ship 
may  be  inferred  with  accuracy  from  the  foam-streaks  oil  the  surface 
of  the  sea. 


136  FRAGMENTS  OF  SCIENCE. 

really,"  says  Dean  Peacock,  "no  taste  for  life  in  the  coun- 
try: "he  was  one  of  those  who  thought  that  no  one  who  was 
able  to  live  in  London  would  be  content  to  live  elsewhere." 
Well,  Dr.  Young,  like  Dr.  Johnson,  had  a  right  to  his  de- 
lights; but  I  can  understand  a  hesitation  to  accept  them, 
high  as  they  were,  to  the  exclusion  of 

That  o'erflowing  joy  which  Nature  yields 
To  her  true  lovers. 

To  all  who  are  of  this  mind,  the  strengthening  of  desire  on 
my  part  to  see  and  know  Niagara  Falls  as  far  as  it  is  pos- 
sible for  them  to  be  seen  and  known,  will  be  intelligible. 


On  the  first  evening  of  my  visit,  i  met,  at  the  head  of 
JLJuWteVSEati-,  the  guide  to  the  Cave  of  the  Winds.  He 
was  in  the  prime  of  manhood — large,  well  -built,  firm  and 
pleasant jn  mouth  and_eye.  lily  interest  in  the  scene 
stirred  up  his,  and  made  him  communicative.  Turning  to 
a  photograph,  he  described,  by  reference  to  it,  a  feat  which 
he  had  accomplished  some  time  previously,  and  which  had 
brought  him  almost  under  the  green  water  of  the  Horse- 
shoe Fall.  "Can  you  lead  me  there  to-morrow?"  I  asked. 
He  eyed  me  inquiringly,  weighing,  perhaps,  the  chances  of 
a  man  of  light  build,  and  with  gray  in  his  whiskers,  in  such 
an  undertaking.  "  I  wish,"  I  added,  "  to  see  as  much  of 
the  fall  as  can  be  seen,  and  where  you  lead  I  will  endeavor 
to  follow."  His  scrutiny  relaxed  into  a  smile,  and  he  said, 
"  Very  well;  I  shall  be  ready  for  you  to-morrow." 

On  the  morrow,  accordingly,  I  came.  In  the  hut  at  the 
head  of  Biddle's  Stair  I  stripped  wholly,  and  re  dressed 
according  to  instructions — drawing  on  two  pairs  of  woolen 
pantaloons,  three  woolen  jackets,  two  pairs  of  socks,  and  a 
pair  of  felt  shoes.  Even  if  wet,  my  guide  assured  me  that 
the  clothes  would  keep  me  from  being  chilled;  and  he  was 
right.  A  suit  and  hood  of  yellow  oilcloth  covered  all. 
Most  laudable  precautions  were  taken  by  the  young  assist- 
ant who  helped  to  dress  me  to  keep  the  water  out;  but 
his  devices  broke  down  immediately  when  severely  tested, 
i/  We  descended  the  stair;  the  handle  of  a  pitchfork  doing, 
in  my  case,  the  duty  of  an  alpenstock.  At  the  bottom,  the 
guide  inquired  whether  we  should  go  first  to  the  Cave  of 
the  Winds,  or  to  the  Horseshoe,  remarking  that  the  latter 
would  try  us  most.  I  decided  on  getting  the  roughest  done 


I  jN, 


NIAGARA.  13? 

first,  and  he  turned  to  the  left  over  the  stones.  They  were 
sharp  and  trying.  The  base  of  the  first  portion  of  the  cat- 
aract is  covered  with  huge  boulders,  obviously  the  ruins  of 
the  limestone  ledge  above.  The  water  does  not  distribute 
itself  uniformly  among  these,  but  seeks  out  channels 
through  which  it  pours  torrentially.  We  passed  some  of 
these  with  wetted  feet,  but  without  difficulty.  At  length 
we  came  to  the  side  of  a  more  formidable  current.  My 
guide  walked  along  its  edge  until  he  reached  its  least  turbu- 
lent portion.  Halting,  he  said,  "This  is  our  greatest  diffi- 
culty; if  we  can  cross  here,  we  shall  get  far  toward  the 
Horseshoe." 

He  waded  in.  It  evidently  required  all  his  strength  to 
steady  him.  The  water  rose  above  his  loins,  and  it 
foamed  still  higher.  He  had  to  search  for  footing,  amid 
unseen  boulders,  against  which  the  torrent  rose  violently. 
He  struggled  and  swayed,  but  he  struggled  successfully, 
and  finally  readied  the  shallower  water  at  the  other  side. 
Stretching  out  his  arm,  he  said  to  me,  "  Now  come  on." 
I  looked  down  the  torrent,  as  it  rushed  to  the  river  below, 
which  was  seething  with  the  tumult  of  the  cataract.  De 
Sanssure  recommended  the  inspection  of  Alpine  dangers, 
with  the  view  of  making  them  familiar  to  the  eye  before 
they  are  encountered;  and  it  is  a  wholesome  custom  in 
places  of  difficulty  to  put  the  possibility  of  an  accident 
clearly  before  the  mind,  and  to  decide  beforehand  what 
i  ought  to  be  done  should  the  accident  occur.  Thus  wound 
up  in  the  present  instance,  I  entered  the  water.  Even 
where  it  was  not  more  than  knee -deep,  its  power  was 
manifest.  As  it  rose  around  me,  I  sought  to  split  the 
torrent  by  presenting  a  side  to  it;  but  the  insecurity  of  the 
footing  enabled  it  to  grasp  my  loins,  twist  me  fairly  round, 
and  bring  its  impetus  to  bear  upon  my  back.  Further 
struggle  was  impossible;  and  feeling  my  balance  hopelessly 
gone,  I  turned,  flung  myself  toward  the  bank  just  quitted, 
and  was  instantly,  as  expected,  swept  into  shallower 
water. 

The  oilcloth  covering  was  a  great  incumbrance;  it  had 
been  made  for  a  much  stouter  man,  and,  standing  upright 
after  my  submersion,  my  legs  occupied  the  center  of  two  bags 
of  water.  My  guide  exhorted  me  to  try  again.  Prudence 
was  at  my  elbow,  whispering  dissuasion;  but,  taking  every- 
thing into  account,  it  appeared  more  immoral  to  retreat 


138  FRAGMENTS  OF  SCIENCE. 

than  to  proceed.  Instructed  by  the  first  misadventure,  I 
once  more  entered  the  stream.  Had  the  alpenstock  been 
of  iron  it  might  have  helped  me;  but,  as  it  was,  the  ten- 
dency of  the  water  to  sweep  it  out  of  my  hands  rendered 
it  worse  than  useless.  I,  however,  clung  to  it  by  habit. 
Again  the  torrent  rose  and  again  I  wavered;  but,  by  keep- 
ing the  left  hip  well  against  it,  I  remained  upright,  and  at 
length  grasped  the  hand  of  my  leader  at  the  other  sfde. 
He  laughed  pleasantly.  The  first  victory  was  gained,  and 
he  enjoyed  it.  "  No  traveler,"  he  said,  "  was  ever  here 
before."  Soon  afterward,  by  trusting  to  a  piece  of  drift- 
wood which  seemed  firm,  I  was  again  taken  off  my  feet, 
but  was  immediately  caught  by  a  protruding  rock. 

We  clambered  over  the  boulders  toward  the  thickest 
spray,  which  soon  became  so  weighty  as  to  cause  us  to 
stagger  under  its  shock.  For  the  most  part  nothing  could 
be  seen;  we  were  in  the  midst  of  bewildering  tumult,  lushed 
by  the  water,  which  sounded  at  times  like  the  cracking  of 
innumerable  whips.  Underneath  this  was  the  deep 
resonant  roar  of  the  cataract.  I  tried  to  shield  my  eyes 
with  my  hands,  and  look  upward;  but  the  defense  was  use- 
less. The  guide  continued  to  move  6n,  but  at  a  certain 
place  he  halted,  desiring  me  to  take  shelter  in  his  lee,  and 
observe  the  cataract.  The  spray  did  not  come  so  much 
from  the  upper  ledge,  as  from  the  rebound  of  the  shattered 
water  when  it  struck  the  bottom.  Hence  the  eyes  could 
be  protected  from  the  blinding  shock  of  the  spray,  while 
the  line  of  vision  to  the  upper  ledges  remained  to  some 
extent  clear.  On  looking  upward  over  the  guide's  shoulder 
I  could  see  the  water  bending  over  the  ledge,  while  the 
Terrapin  Tower  loomed  fitfully  through  the  intermittent 
spray-gusts.  We  w^ere  right  under  the  tower.  A  little 
farther  on  the  cataract;-alter-its  first  plunge,  hit  a  pro- 
tuberance some  way  down,  and  flew  from  it  in  a  prodigious 
burst  of  spray;  through  this  we  staggered.  We  rounded 
the  promontory  on  which  the  Terrapin  Tower  stands,  and 
moved,  amid  the  wildest  commotion,  along  the  arm  of  the 
Horseshoe,  until  the  boulders  failed  us,  and  the  cataract 
fell  into  the  profound  gorge  of  the  Niagara  river. 

Here  the  guide  sheltered  me  again,  and  desired  me  to 
look  up;  I  did  so,  and  could  see,  as  before,  the  green 
gleam  of  the  mighty  curve  sweeping  over  the  upper  ledge, 
and  the  fitful  plunge  of  the  water,  as  the  spray  between  us 


NIAGARA.  139 

and  it  alternately  gathered  and  disappeared.  An  eminent 
friend  of  mine  often  speaks  of  the  mistake  of  those  phy- 
sicians who  regard  man's  ailments  as  purely  chemical,  to 
be  met  by  chemical  remedies  only.  He  contends  for  the 
psychological  element  of  cure.  By  agreeable  emotions,  he 
says,  nervous  currents  are  liberated  which  stimulate  blood, 
brain,  and  viscera.  ,i  The  influence  rained  from  ladies'  eyes 
enables  my  friend  to  thrive  on  dishes  which  would  kill 
him  if  eaten  alone j/  A  sanative  effect  of  the  same  order  I 
experienced  amid '  the'spTay an3  thunder  of  Niagara.  Q  (^ 
Quickened  by  the  emotions  there  aroused,  the  blood  sped  ^t- 
exultingly  through  the  arteries,  abolishing  introspection, 
clearing  the  heart  of  all  bitterness,  and  enabling  one  to 
think  with  tolerance,  if  not  with  tenderness,  on  the  most 
relentless  and  unreasonable  foe.  Apart  from  its  scientitic 
value,  and  pinielyjis_-a._mx>ral-»gen4rtEe:plfty "was "worth  the/ 
candle.  My  companion  knew  no  more  of  me  than  that  I 
enjoyed  the  wildness  of  the  scene;  but  as  I  bent  in  the 
shelter  of  his  large  frame  he  said,  "I  should  like  to  sec 
you  attempting  to  describe  all  this."  He  rightly  thought 
it  indescribable.  The  name  of  this  gallant  fellow  was 
Thomas  Conroy. 

We~retiirned,  clambering  at  intervals  up  and  down,  so 
as  to  catch  glimpses  of  the  most  impressive  portions  of  the 
cataract.  We  passed  under  ledges  formed  by  tabular 
masses  of  limestone,  and  through  some  curious  openings 
formed  by  the  falling  together  of  the  summits  of  the  rocks. 
At  length  we  found  ourselves  beside  our  enemy  of  the 
morning.  Conroy  halted  for  a  minute  or  two,  scanning 
the  torrent  thoughtfully.  I  said  that,  as  a  guide,  he  ought 
to  have  a  rope  in  such  a  place;  but  he  retorted  that,  as  no 
traveler  had  ever  thought  of  coming  there,  he  did  not  see 
the  necessity  of  keeping  a  rope.  He  waded  in.  The 
struggle  to  keep  himself  erect  was  evident  enough;  he 
swayed,  but  recovered  himself  again  and  again.  At  length 
he  slipped,  gave  way,  did  as  I  had  done,  threw  himself 
toward  the  bank,  and  was  swept  into  the  shallows.  Stand- 
ing in  the  stream  near  its  edge,  he  stretched  his  arm 
toward  me.  I  retained  the  pitchfork  handle,  for  it  had 
been  useful  among  the  boulders.  By  wading  some  way  in, 
the  staff  could  be  made  to  reach  him,  and  I  proposed  his 
seizing  it.  "  If  you  are  sure,"  he  replied,  "  that,  in  case 
of  giving  way,  you  can  maintain  your  grasp,  then  I  will 


140  FRAGMENTS  Off  SCIENCE. 

certainly  hold  you."  Remarking  that  he  might  count  on 
this,  I  waded  in,  and  stretched  the  staff  to  rny  companion. 
It  was  firmly  grasped  by  both  of  us.  Thus  helped,  though 
its  onset  was  strong,  I  moved  safely  across  the  torrent. 
All  danger  ended  here.  We  afterward  roamed  sociably 
among  the  torrents  and  boulders  below  the  Gave  of  the 
Winds.  The  rocks  were  covered  with  organic  slime,  which 
could  not  have  been  walked  over  with  bare  feet,  but  the 
felt  shoes  effectually  prevented  slipping.  We  reached  the 
cave  and  entered  it,  first  by  a  wooden  way  carried  over  the 
boulders,  and  then  along  a  narrow  ledge,  to  the  point  eaten 
deepest  into  the  shale.  When  the  wind  is  from  the  south, 
the  falling  water,  I  am  told,  can  be  seen  tranquilly  from 
this  spot;  but  when  we  were  there,  a  blinding  hurricane 
of  spray  was  whirled  against  us.  On  the  evening  of  the 
same  day,  I  went  behind  the  water  on. the  Canada  side, 
which,  after  the  experiences  of  the  morning,  strucTTnle  as 
anim  posture. 

Still  even  this  latter  is  exciting  to  some  nerves.  Its 
effect  upon  himself  is  thus  vividly  described  by  Mr. 
Bakewell,  Jr.:  "On  turning  a  sharp  angle  of  the  rock, 
a  sudden  gust  of  wind  met  us,  coming  from  the  hollow  be- 
tween the  fall  and  the  rock,  which  drove  the  spray  directly 
in  our  faces,  with  such  force  that  in  an  instant  we  were 
wet  through.  When  in  the  midst  of  this  shower-bath  the 
shock  took  away  my  breath:  I  turned  back  and  scrambled 
over  the  loose  stones  to  escape  the  conflict.  The  guide 
soon  followed,  and  told  me  that  I  had  passed  the  worst 
part.  With  that  assurance  I  made  a  second  attempt;  but 
so  wild  and  disordered  was  my  imagination  that  when  I 
had  reached  halfway  I  could  bear  it  no  longer."* 

To  complete  my  knowledge  I  desired  to  see  the  fall  from 
the  river  below  it,  and  long  negotiations  were  necessary  to 
secure  the  means  of  doing  so.  The  only  boat  fit  for  the 
undertaking  had  been  laid  up  for  the  winter;  but  this 
difficulty,  through  the  kind  intervention  of  Mr.  Townsend, 
was  overcome.  The  main  one  was  to  secure  oarsmen 
sufficiently  strong  and  skillful  to  urge  the  boat  where  I 
wished  it  to  be  taken.  The  son  of  the  owner  of  the  boat, 
a  finely  built  young  fellow,  but  only  twenty,  and  therefore 
not  sufficiently  hardened,  was  willing  to  go;  and  up  the 

*  "Mag.  of  Nat.  Hist.,"  1830,  pp.  121,  122. 


NIAGARA.  Ul 

river,  it  was  stated,  there  lived  another  man  who  could  do 
anything  with  the  boat  which  strength  and  daring  could 
accomplish.  He  came.  His  figure  and  expression  of  face 
certainly  indicated  extraordinary  firmness  and  power.  On 
Tuesday,  November  5th,  we  started,  each  of  us  being  clad 
in  oilcloth.  The  elder  oarsman  at  once  assumed  a  tone  of 
authority  over  his  companion,  and  struck  immediately  in 
amid  the  breakers  below  the  American  Fall.  He  hugged 
the  cross  freshets  instead  of  striking  out  into  the  smoother 
water.  I  asked  him  why  he  did  so,  and  he  replied  that 
they  were  directed  outward,  not  downward.  The  struggle, 
however,  to  prevent  the  bow  of  the  boat  from  being  turned 
by  them,  was  often  very  severe. 

The  spray  was  in  general  blinding,  but  at  times  it  dis- 
appeared and  yielded  noble  views  of  the  fall.  The  edge  of 
the  cataract  is  crimped  by  indentations  which  exalt  its 
beauty.  Here  and  there,  a  little  below  the  highest  ledge, 
a  secondary  one  juts  out;  the  water  strikes  it  and  bursts 
from  it  in  huge  protuberant  masses  of  foam  and  spray. 
We  passed  Goat  Island,  came  to  the  Horseshoe,  and  worked 
for  a  time  along  its  base,  the  boulders  over  which  Conroy 
and  myself  had  scrambled  a  few  days  previously  lying  be- 
tween us  and  the  cataract.  A  rock  was  before  us,  concealed 
and  revealed  at  intervals,  as  the  waves  passed  over  it.  Our 
leader  tried  to  get  above  this  rock,  first  on  the  outside  of 
it.  The  water,  however,  was  here  in  violent  motion.  The 
men  struggled  fiercely,  the  older  one  ringing  out  an  inces- ' 
sant  peal  of  command  and  exhortation  to  the  younger.  As 
we  were  just  clearing  the  rock,  the  bow  came  obliquely  to 
the  surge;  the  boat  was  turned  suddenly  round  and  shot 
with  astonishing  rapidity  down  the  river.  The  men  re- 
turned to  the  charge,  now  trying  to  get  up  between  the 
half-concealed  rock  and  the  boulders  to  the  left.  But  the 
torrent  set  in  strongly  through  this  channel.  The  tugging 
was  quick  and  violent,  but  we  made  little  way.  At  length, 
seizing  a  rope,  the  principal  oarsman  made  a  desperate 
attempt  to  get  upon  one  of  the  boulders,  hoping  to  be  able 
to  drag  the  boat  through  the  channel;  but  it  bumped  so 
violently  against  the  rock,  that  the  man  flung  himself  back 
and  relinquished  the  attempt. 

We  returned  along  the  base  of  the  American  Fall,  run- 
ning in  and  out  among  the  currents  which  rushed  from  it 
laterally  into  the  river,  Seen  from  below  the  American 


142  FRAGMENTS  OF  SCIENCE. 

Fall  is  certainly  exquisitely  beautiful,  but  it  is  a  mere 
frill  of  adornment  to  its  nobler  neighbor  the  Horseshoe.  At 
times  we  took  to  the  river,  from  the  center  of  wbich  the 
Horseshoe  Fall  appeared  especially  magnificent.  A  streak 
of  cloud  across  the  neck  of  Mont  Blanc  can  double  its  ap- 
parent height,  so  here  the  green  summit  of  the  cataract 
shining  above  the  smoke  of  spray  appeared  lifted  to  an  ex- 
traordinary elevation.  Had  Hennepin  and  La  Hontan 
seen  the  fall  from  this  position,  their  estimates  of  the 
height  would  have  been  perfectly  excusable. 

From  a  point  a  little  way  below  the  American  Fall,  a 
ferry  crosses  the  river,  in  summer,  to  the  Canadian  side. 
Below  the  ferry  is  a  suspension  bridge  for  carriages  and 
foot-passengers,  and  a  mile  or  two  lower  down  is  the  rail- 
way suspension  bridge.  Between  ferry  and  bridge  the 
river  Niagara  flows  unruffled:  but  at  the  suspension  bridge 
the  bed  steepens  and  the  river  quickens  its  motion.  Lower 
down  the  gorge  narrows,  and  the  rapidity  and  turbulence 
increase.  At  the  place  called  the  "  Whirlpool  Rapids"  I 
estimated  the  width  of  the  river  at  300  feet,  an  estimate 
confirmed  by  the  dwellers  on  the  spot.  When  it  is  remem- 
bered that  the  drainage  of  nearly  half  a  continent  is  com- 
pressed into  this  space,  the  impetuosity  of  the  river's  rush 
may  be  imagined.  Had  it  not  been  for  Mr.  Bierstadt,  the 
distinguished  photographer  of  Niagara,  I  should  have 
quitted  the  place  without  seeing  these  rapids;  for  this,  and 
for  his  agreeable  company  to  the  spot,  I  have  to  thank  him. 
From  the  edge  of  the  cliff  above  the  rapids,  we  descended, 
a  little,  I  confess,  to  a  climber's  disgust,  in  an  "  elevator," 
because  the  effects  are  best  seen  from  the  water  level. 

Two  kinds  of  motion  are  here  obviously  active,  a  motion 
of  translation  and  a  motion  of  undulation — the  race  of  the 
river  through  its  gorge,  and  the  great  waves  generated  by 
its  collision  with,  and  rebound  from,  the  obstacles  in  its 
way.  In  the  middle  of  the  river  the  rush  and  tossing  are 
most  violent;  at  all  events,  the  impetuous  force  of  the 
individual  waves  is  here  most  strikingly  displayed.  Vast 
pyramidal  heaps  leap  incessantly  from  the  river,  some  of 
them  with  such  energy  as  to  jerk  their  summits  into  the 
air,  where  they  hang  momentarily  suspended  in  crowds  of 
liquid  spherules.  The  sun  shone  for  a  few  minutes.  At 
times  the  wind,  coming  up  the  river,  searched  and  sifted 


NIAGARA.  143 

the  spray,  carrying  away  the  lighter  drops,  and  leaving  the 
heavier  ones  behind.  Wafted  in  the  proper  direction, 
rainbows  appeared  and  disappeared  fitfully  in  the  lighter 
mist.  In  other  directions  the  common  gleam  of  the  sun- 
shine from  the  waves  and  their  shattered  crests  was  exqui- 
sitely beautiful.  The  complexity  of  the  action  was  still 
further  illustrated  by  the  fact,  that  in  some  cases,  as  if  by 
the  exercise  of  a  local  explosive  force,  the  drops  were  shot 
radially  from  a  particular  center,  forming  around  it  a  kind 
of  halo. 

The  first  impression,  and,  indeed,  the  current  explana- 
tion of  these  rapids  is,  that  the  central  bed  of  the  river  is 
cumbered  with  large  boulders,  and  that  the  jostling,  toss- 
ing, and  wild  leaping  of  the  water  there,  are  due  to  its 
impact  against  these  obstacles.  I  doubt  this  explanation. 
At  all  events,  there  is  another  sufficient  reason  to  be  taken 
into  account.  Boulders  derived  from  the  adjacent  cliffs 
visibly  cumber  the  sides  of  the  river.  Against  these  the 
water  rises  and  sinks  rhythmically  but  violently,  large  waves 
being  thus  produced.  On  the  generation  of  each  wave, 
there  is  an  immediate  compounding  of  the  wave-motion 
with  the  river-motion.  The  ridges  which  in  still  water 
would  proceed  in  circular  curves  round  the  center  of  dis- 
turbance, cross  the  river  obliquely,  and  the  result  is  that 
at  the  center  waves  commingle,  which  have  really  been 
generated  at  the  sides.  In  the  first  instance,  we  had  a 
composition  of  wave-motion  with  river-motion;  here  we 
have  the  coalescence  of  waves  with  waves.  Where  crest 
and  furrow  cross  each  other,  the  motion  is  annulled;  where 
furrow  and  furrow  cross,  the  river  is  plowed  to  a  greater 
depth;  and  where  crest  and  crest  aid  each  other,  we  have 
that  astonishing  leap  of  the  water  which  breaks  the  cohe- 
sion of  the  crests,  and  tosses  them  shattered  into  the  air. 
From  the  water  level  the  cause  of  the  action  is  not  so  easily 
seen,  but  from  the  summit  of  the  cliff  the  lateral  gener- 
ation of  the  waves,  and  their  propagation  to  the  center, 
are  perfectly  obvious.  If  this  explanation  be  correct,  the 
phenomena  observed  at  the  Whirlpool  Rapids  form  one  of 
the  grandest  illustrations  of  the  principle  of  interference. 
The  Nile  "cataract,"  Mr.  Huxley  informs  me,  offers 
more  moderate  examples  of  the  same  action. 

At  some  distance  below  the  Whirlpool  Rapids  we  have 
the  celebrated  whirlpool  itself.  Here  the  river  makes  a, 


144  FRAGMENTS  OF  SCIENCE. 

sudden  bend  to  the  northeast,  forming  nearly  a  right 
angle  with  its  previous  direction.  The  water  strikes  the 
concave  bank  with  great  force,  and  scoops  it  incessantly 
away.  A  vast  basin  has  been  thus  formed,  in  which  the 
sweep  of  the  river  prolongs  itself  in  gyratory  currents. 
Bodies  and  trees  which  have  come  over  the  falls,  are  stated 
to  circulate  here  for  days  without  finding  the  outlet.  From 
various  points  of  the  cliffs  above,  this  is  curiously  hidden. 
The  rush  of  the  river  into  the  whirlpool  is  obvious  enough; 
and  though  you  imagine  the  outlet  must  be  visible,  if  one 
existed,  you  cannot  find  it.  Turning,  however,  round  the 
bend  of  the  precipice  to  the  northeast,  the  outlet  comes 
into  view. 

The  Niagara  season  was_over;  the  chatter  of  sightseers 
had^ceaseHT" and  the  scene~~p resented  itself  as  one  of  holy 
seclusion  and  beauty.  I  went  down  to  the  river's  edge, 
wKere  the  weird  loneliness  seemed  to  increase.  The  basin 
is  enclosed  by  high  and  almost  precipitous  banks — covered, 
at  the  time,  with  russet  woods.  A  kind  of  mystery  attaches 
itself  to  gyrating  water,  due  perhaps  to  the  fact  that  we 
are  to  some  extent  ignorant  of  the  direction  of  its  force. 
It  is  said  that  at  certain  points  of  the  whirlpool,  pine  trees 
are  sucked  down,  to  be  ejected  mysteriously  elsewhere. 
The  water  is  of  the  brightest  emerald-green.  The  gorge 
through  which  it  escapes  is  narrow,  and  the  motion  of  the 
river  swift  though  silent.  The  surface  is  steeply  inclined, 
but  it  is  perfectly  unbroken.  There  are  no  lateral  waves, 
no  ripples  with  their  breaking  bubbles  to  raise  a  murmur; 
while  the  depth  is  here  too  great  to  allow  the  inequality  of 
the  bed  to  ruffle  the  surface.  Nothing  can  be  more  beauti- 
ful than  this  sloping  liquid  mirror  formed  by  the  Niagara, 
in  sliding  from  the  whirlpool. 

The  green  color  is,  I  think,  correctly  accounted  for  in 
the  last  Fragment. ,.  While  crossing  the  Atlantic  in  1872-73 
I  had  frequent  opportunities  of  testing  the  explanation 
there  given.  Looked  properly  down  upon,  there  are 
portions  of  the  ocean  to  which  we  should  hardly  ascribe  a 
trace  of  blue;  at  the  most,  a  mere  hint  of  indigo  reaches 
the  eye.  The  water,  indeed,  is  practically  black,  and  this 
is  an  indication  both  of  its  depth  and  of  its  freedom  from 
mechanically  suspended  matter.  In  small  thicknesses 
water  is  sensibly  transparent  to  all  kinds  of  light;  but,  as 
the  thickness  increases,  the  rays  of  low  refrangibility  are 


NIAGARA.  145 

first  absorbed,  and  after  them  the  other  rays.  Where,  there- 
fore, the  water  is  very  deep  and  very  pure,  all  the  colors 
are  absorbed,  and  such  water  ought  to  appear  black,  as  no 
light  is  sent  from  itsinterior  to  the  eye.  The  approximation 
of  the  Atlantic  ocean  to  this  condition  is  an  indication  of 
its  extreme  purity. 

Throw  a  white  pebble  into  such  water;  as  it  sinks  it 
becomes  greener  and  greener,  and,  before  it  disappears,  it 
reaches  a  vivid  blue-green;  Break  such  a  pebble  into 
fragments,  each  of  these  will  behave  like  the  unbroken 
mass;  grind  the  pebble  to  powder,  every  particle  will  yield 
its  modicum  of  green;  and  if  the  particles  be  so  fine  as  to 
remain  suspended  in  the  water,  the  scattered  light  will  be 
a  uniform  green.  Hence  the  greenness  of  shoal  water. 
You  go  to  bed  with  the  black  Atlantic  around  you.  You 
rise  in  the  morning,  find  it  a  vivid  green,  and  correctly 
infer  that  you  are  crossing  the  bank  of  Newfoundland. 
Such  water  is  found  charged  with  fine  matter  in  a  state  of 
mechanical  suspension.  The  light  from  the  bottom  may 
sometimes  come  into  play,  but  it  is  not  necessary.  A  storm 
can  render  the  water  rnuddy,  by  rendering  the  particles 
too  numerous  and  gross.  Such  a  case  occurred  toward  the 
close  of  my  visit  to  Niagara.  There  had  been  rain  and 
storm  in  the  upper  lake-regions,  and  the  quantity  of  sus- 
pended matter  brought  down  quite  extinguished  the  fasci- 
nating green  of  the  Horseshoe. 

Nothing  can  be  more  superb  than  the  green  of  the 
Atlantic  waves,  when  the  circumstances  are  favorable  to 
the  exhibition  of  the  color.  As  long  as  a  wave  remains 
unbroken  no  color  appears;  but  when  the  foam  just  doubles 
over  the  crest,  like  an  Alpine  snow-cornice,  under  the  cor- 
nice we  often  see  a  display  of  the  most  exquisite  green.  It 
is  metallic  in  its  brilliancy.  But  the  foam  is  necessary  to 
its  production.  The  foam  is  first  illuminated,  and  it  scat- 
ters the  light  in  all  directions;  the  light  which  passes 
through  the  higher  portion  of  the  wave  alone  reaches  the 
eye,  and  gives  to  that  portion  its  matchless  color.  The 
folding  of  the  wave,  producing  as  it  does  a  series  of  longi- 
tudinal protuberances  and  furrows  which  act  like  cylindrical 
lenses,  introduces  variations  in  the  intensity  of  the  light, 
and  materially  enhances  its  beauty.  ^*  / 

We  have  now   to  consider  the  genesis  and  proximate 


146  FRAGMENTS  OF  SCIENCE. 

destiny  of  the  Falls  of  Niagara.  "We  may  open  our  way  to 
this  subject  by  a  few  preliminary  remarks  upon  erosion. 
Time  and  intensity  are  the  main  factors  of  geologic  change, 
and  they  are  in  a  certain  sense  convertible.  A  feeble  force 
acting  through  long  periods,  and  an  intense  force  acting 
through  short  ones,  may  produce  approximately  the 
same  results.  To  Dr.  Hooker  I  have  been  indebted  for 
some  specimens  of  stones,  the  first  examples  of  which  were 
picked  up  by  Mr.  Hackvvorth  on  the  shores  of  Lyell's  bay, 
near  Wellington,  in  New  Zealand.  They  were  described 
by  Mr.  Travers  in  the  "  Transactions  of  the  New  Zealand 
Institute."  Unacquainted  with  their  origin,  you  would 
certainly  ascribe  their  forms  to  human  workmanship. 
They  resemble  knives  and  spear-heads,  being  apparently 
chiseled  off  into  facets,  with  as  much  attention  to 
symmetry  as  if  a  tool,  guided  by  human  intelligence, 
had  passed  over  them.  But  no  human  instrument  has 
been  brought  to  bear  upon  these  stones.  They  have  been 
wrought  into  their  present  shape  by  the  wind-blown  sand 
of  Lyell's  bay.  Two  winds  are  dominant  here,  and  they 
in  succession  urged  the  sand  against  opposite  sides  of  the 
stone;  every  little  particle  of  sand  chipped  away  its  infini- 
tesimal bit  of  stone,  and  in  the  end  sculptured  these  sin- 
gular forms.* 

The  Sphinx  of  Egypt  is  nearly  covered  up  by  the  sand 
of  the  desert.  The  neck  of  the  Sphinx  is  partly  cut  across. 

*  "These  stones,  which  have  a  strong  resemblance  to  works  of 
human  art,  occur  in  great  abundance,  and  of  various  sizes,  from  half- 
an  inch  to  several  inches  in  length.  A  large  number  were  exhibited 
showing  the  various  forms,  which  are  those  of  wedges,  knives, 
arrow-heads,  etc.,  and  all  with  sharp  cutting  edges. 

"  Mr.  Travers  explained  that,  notwithstanding  their  artificial 
appearance,  these  stones  were  formed  by  the  cutting  action  of  the 
wind-driven  sand,  as  it  passed  to  and  fro  over  an  exposed  boulder- 
bank.  He  gave  a  minute  account  of  the  manner  in  which  the  varie- 
ties of  form  are  produced,  and  referred  to  the  effect  which  the  erosive 
action  thus  indicated  would  have  on  railway  and  other  works  exe- 
cuted on  sandy  tracts. 

"Dr.  Hector  stated  that  although,  as  a  group,  the  specimens  on 
the  table  could  not  well  be  mistaken  for  artificial  productions,  still 
the  forms  are  so  peculiar,  and  the  edges,  in  a  few  of  them,  so  per- 
fect, that  if  they  were  discovered  associated  with  human  works,  there 
is  no  doubt  that  they  would  have  been  referred  to  the  so-called 
'stone  period.'"—  Kxtr acted  from  the  Mimites  of  the  Wellington 
Philosophical  Society,  February  9,  1869. 


NIAGARA.  147 

not,  as  I  am  assured  by  Mr.  Huxley,  by  ordinary  weather- 
ing, but  by  the  eroding  action  of  the  fine  sand  blown 
against  it.  In  these  cases  Nature  furnishes  us  with  hints 
which  may  be  taken  advantage  of  in  art;  and  this  action 
of  sand  has  been  recently  turned  to  extraordinary  account 
in  the  United  States.  When  in  Boston,  I  was  taken  by 
my  courteous  and  helpful  friend,  Mr.  Josiah  Quincey,  to 
see  the  action  of  the  sand-blast.  A  kind  of  hopper  con- 
taining fine  silicious  sand  was  connected  with  a  reservoir 
of  compressed  air,  the  pressure  being  variable  at  pleasure. 
The  hopper  ended  in  a  long  slit,  from  which  the  sand  was 
blown.  A  plate  of  glass  was  placed  beneath  this  slit,  and 
caused  to  pass  slowly  under  it;  it  came  out  perfectly 
depolished,  with  a  bright  opalescent  glimmer,  such  as 
could  only  be  produced  by  the  most  careful  grinding. 
Every  little  particle  of  sand  urged  against  the  glass,  having 
all  its  energy  concentrated  on  the  point  of  impact,  formed 
there  a  little  pit,  the  depolished  surface  consisting  of  in- 
numerable hollows  of  this  description. 

But  this  was  not  all.  By  protecting  certain  portions  of 
the  surface,  and  exposing  others,  figures  and  tracery  of  any 
required  form  could  be  etched  upon  the  glass.  The  figures 
of  open  iron-work  could  be  thus  copied;  while  wire-gauze 
placed  over  the  glass  produced  a  reticulated  pattern.  But 
it  required  no  such  resisting  substance  as  iron  to  shelter 
the  glass.  The  patterns  of  the  finest  lace  could  be  thus 
reproduced;  the  delicate  filaments  of  the  lace  itself  offering 
a  sufficient  protection.  All  these  effects  have  been  obtained 
with  a  simple  model  of  the  sand-blast  devised  by  my  assist- 
ant. A  fraction  of  a  minute  suffices  to  etch  upon  glass  a 
rich  and  beautiful  lace  pattern.  Any  yielding  substance 
may  be  employed  to  protect  the  glass.  By  diffusing  the 
shock  of  the  particle,  such  substances  practically  destroy 
the  local  erosive  power.  The  hand  can  bear,  without  in- 
convenience, a  sand-shower  which  would  pulverize  glass. 
Etchings  executed  on  glass  with  suitable  kinds  of  ink  are 
accurately  worked  out  by  the  sand-blast.  In  fact,  within 
certain  limits,  the  harder  the  surface,  the  greater  is  the 
concentration  of  the  shock,  and  the  more  effectual  is  the 
erosion.  It  is  not  necessary  that  the  sand  should  be  the 
harder  substance  of  the  two;  corundum,  for  example,  is 
much  harder  than  quartz;  still,  quartz-sand  can  not  only 
depolish,  but  actually  blow  a  hole  through  a  plate  of  corun- 


]  48  fRA  GMENTS  Off  SCIENCE. 

dum.  Nay,  glass  may  be  depolished  by  the  impact  of  fine 
shot;  the  grains  in  this  case  bruising  the  glass,  before  they 
have  time  to  flatten  and  turn  their  energy  into  heat. 

And  here,  in  passing,  we  may  tie  together  one  or  two 
apparently  unrelated  facts.  Supposing  you  turn  on,  at  the 
lower  part  of  a  house,  a  cock  which  is  fed  by  a  pipe  from 
a  cistern  at  the  top  of  the  house,  the  column  of  water, 
from  the  cistern  downward,  is  set  in  motion.  By  turning 
off  the  cock,  this  motion  is  stopped;  and  when  the  turning 
off  is  very  sudden,  the  pipe,  if  not  strong,  may  be  burst  by 
the  internal  impact  of  the  water.  By  distributing  the 
turning  of  the  cock  over  half  a  second  of  time,  the  shock  and 
and  danger  of  rupture  may  be  entirely  avoided.  We  have 
here  an  example  of  the  concentration  of  energy  in  time. 
The  sand-blast  illustrates  the  concentration  of  energy  in 
space.  The  action  of  flint  and  steel  is  an  illustration  of 
the  same  principle.  The  heat  required  to  generate  the 
spark  is  intense;  and  the  mechanical  action,  being  moder- 
ate, must,  to  produce  fire,  be  in  the  highest  degree  con- 
centrated. This  concentration  is  secured  by  the  collision 
of  hard  substances.  Calc-spar  will  not  supply  the  place  of 
flint,  nor  lead  the  place  of  steel,  in  the  production  of  fire 
by  collision.  With  the  softer  substances,  the  total  heat 
produced  may  be  greater  than  with  the  hard  ones,  but, 
to  produce  the  spark,  the  heat  must  be  intensely  local- 
ized. 

We  can,  however,  go  far  beyond  the  mere  depolishing  of 
glass;  indeed  I  have  already  said  that  quartz-sand  can 
wear  a  hole  through  corundum.  This  leads  me  to  express 
my  acknowledgments  to  General  Tilghrnan,*  who  is  the 
inventor  of  the  sand-blast.  To  his  spontaneous  kindness  I 
am  indebted  for  some  beautiful  illustrations  of  his  process. 
In  one  thick  plate  of  glass  a  figure  has  been  worked  out  to 
a  depth  of  three-eighths  of  an  inch.  A  second  plate,  seven- 
eighths  of  an  inch  thick,  is  entirely  perforated.  In  a  circu- 

*The  absorbent  power,  if  I  may  use  the  phrase,  exerted  by  the 
industrial  arts  in  the  United  States,  is  forcibly  illustrated  by  the 
rapid  transfer  of  men  like  Mr.  Tilghraan  from  the  life  of  the  soldier 
to  that  of  the  civilian.  General  McClellan,  now  a  civil  engineer,  whom 
I  had  the  honor  of  frequently  meeting  in  New  York,  is  a  most  emi- 
nent example  of  the  same  kind.  At  the  end  of  the  war,  indeed,  a 
million  and  a  half  of  men  were  thus  drawn,  in  an  astonishingly  short 
time,  from  military  to  civil  life. 


NIAGARA.  149 

lar  plate  of  marble,  nearly  half  an  inch  thick,  open  work  of 
most  intricate  and  elaborate  description  has  been  executed. 
It  would  probably  take  many  days  to  perform  this  work  by 
any  ordinary  process;  with  the  sand-blast  it  was  accom- 
plished in  an  hour.  So  much  for  the  strength  of  the  blast; 
its  delicacy  is  illustrated  by  this  beautiful  example  of  line 
engraving,  etched  on  glass  by  means  of  the  blast. 

This  power  of  erosion,  so  strikingly  displayed  when  sand 
is  urged  by  air,  renders  us  better  able  to  conceive  its  action 
when  urged  by  water.  The  erosive  power  of  a  river  is 
vastly  augmented  by  the  solid  matter  carried  along  with  it. 
Sand  or  pebbles,  caught  in  a  river  vortex,  can  wear  away 
the  hardest  rock;  "  potholes"  and  deep  cylindrical  shafts 
being  thus  produced.  An  extraordinary  instance  of  this 
kind  of  erosion  is  to  be  seen  in  the  Val  Tournanche,  above 
the  village  of  this  name.  The  gorge  of  Handeck  has  been 
thus  cut  out.  Such  waterfalls  were  once  frequent  in  the  val- 
leys of  Switzerland;  for  hardly  any  valley  is  without  one  or 
more  transverse  barriers  of  resisting  material,  over  which 
the  river  flowing  through  the  valley  once  fell  as  a  cataract. 
Near  Pontresina,  in  the  Engadin,  there  is  such  a  case;  a 
hard  gneiss  being  there  worn  away  to  form  a  gorge,  through 
which  the  river  from  the  Morteratsch  glacier  rushes.  The 
barrier  of  the  Kirchet  above  Meyringen  is  also  a  case  in 
point.  Behind  it  was  a  lake,  derived  from  the  glacier  of 
the  Aar,  and  over  the  barrier  the  lake  poured  its  excess  of 
water.  Here  the  rock,  being  limestone,  was  in  part  dis- 
solved; but  added  to  this  we  had  the  action  of  the  sand 
and  gravel  carried  along  by  the  water,  which,  on  striking 
the  rock,  chipped  it  away  like  the  particles  of  the  sand- 
blast. Thus,  by  solution  and  mechanical  erosion,  the 
great  chasm  of  the  Finsteraarschlucht  was  formed.  It  is 
demonstrable  that  the  water  which  flows  at  the  bottoms  of 
such  deep  fissures  once  flowed  at  the  level  of  their  present 
edges,  and  tumbled  down  the  lower  faces  of  the  barriers. 
Almost  every  valley  in  Switzerland  furnishes  examples  of 
this  kind;  the  untenable  hypothesis  of  earthquakes,  once 
so  readily  resorted  to  in  accounting  for  these  gorges,  being 
now  for  the  most  part  abandoned.  To  produce  the  canons 
of  western  America,  no  other  cause  is  needed  than  the  in- 
tegration of  effects  individually  infinitesimal. 

And  now  we  come  to  Niagara.  Soon  after  Europeans 
had  taken  possession,  of  the  country,  the  conviction  appears 


150  FRAGMENTS  OF  SCIENCE. 

to  have  arisen  that  the  deep  channel  of  the  river  Niagara 
below  the  falls  had  been  excavated  by  the  cataract.  In  Mr. 
Bakewell's  "  Introduction  to  Geology,"  the  prevalence  of 
this  belief  has  been  referred  to.  It  is  expressed  thus  by 
Professor  Joseph  Henry  in  the  "  Transactions  of  the  Albany 
Institute:  "  *  "  In  viewing  the  position  of  the  falls,  and  the 
features  of  the  country  round,  it  is  impossible  not  to  be  im- 
pressed with  the  idea  that  this  great  natural  raceway  has 
been  formed  by  the  continued  action  of  the  irresistible 
Niagara,  and  that  the  falls,  beginning  at  Lewiston,  have, 
in  the  course  of  ages,  worn  back  the  rocky  strata  to  their 
present  site."  The  same  view  is  advocated  by  Sir  Charles 
Lyell,  by  Mr.  Hall,  by  M.  Agassiz,  by  Professor  Ram- 
say, indeed  by  most  of  those  who  have  inspected  the 
place. 

A  connected  image  of  the  origin  and  progress  of  the 
cataract  is  easily  obtained.  Walking  northward  from  the 
village  of  Niagara  Falls  by  the  side  of  the  river,  we  have  to 
our  left  the  deep  and  comparatively  narrow  gorge,  through 
which  the  Niagara  flows.  The  bounding  cliffs  of  this 
gorge  are  from  300  to  350  feet  high.  We  reach  the  whirl- 
pool, trend  to  the  northeast,  and  after  a  little  time  gradu- 
ally resume  our  northward  course.  Finally,  at  about 
seven  miles  from  the  present  falls,  we  come  to  the  edge  of  a 
declivity,  which  informs  us  that  we  have  been  hitherto 
walking  on  table-land.  At  some  hundreds  of  feet  below  us 
is  a  comparatively  level  plain,  which  stretches  to  Lake 
Ontario.  The  declivity  marks  the  end  of  the  precipitous 
gorge  of  the  Niagara.  Here  the  river  escapes  from  its  steep 
mural  boundaries,  and  in  a  widened  bed  pursues  its  way  to 
the  lake  which  finally  receives  its  waters. 

The  fact  that  in  historic  times,  even  within  the  memory 
of  man,  the  fall  has  sensibly  receded,  prompts  the  question, 
How  far  lias  this  recession  gone?  At  what  point  did  the 
ledge  which  thus  continually  creeps  backward  begin  its 
retrograde  course?  To  minds  disciplined  in  such  researches 
the  answer  has  been,  and  will  be — At  the  precipitous  de- 
clivity which  crossed  the  Niagara  from  Lewiston  on  the 
American  to  Queenston  on  the  Canadian  side.  Over  this 
transverse  barrier  the  united  affluents  of  all  the  upper  lakes 
once  poured  their  waters,  and  here  the  work  of  erosion  be- 

*  Quoted  by  Bake  welL 


NIAGARA.  151 

gan.  The  dam,  moreover,  was  demonstrably  of  sufficient 
height  to  cause  the  river  above  it  to  submerge  Goat  Island; 
ana.  this  would  perfectly  account  for  the  finding  by  Sir 
Charles  Lyell,  Mr.  Hall,  and  others,  in  the  sand  and  gravel 
of  the  island,  the  same  fluviatile  shells  as  are  now  found  in 
the  Niagara  river  higher  up.  It  would  also  account  for  those 
deposits  along  the  sides  of  the  river,  the  discovery  of  which 
enabled  Lyell,  Hall,  and  Ramsay  to  reduce  to  demonstration 
the  popular  belief  that  the  Niagara  once  flowed  through 
a  shallow  valley. 

The  physics  of  the  problem  of  excavation,  which  I  made 
clear  to  my  mind  before  quitting  Niagara,  are  revealed  by 
a  close  inspection  of  the  present  Horseshoe  Fall.  We  see 
evidently  that  the  greatest  weight  of  water  bends  over  the 
very  apex  of  the  Horseshoe.  In  a  passage  in  his  excellent 
chapter  on  Niagara  Falls,  Mr.  Hall  alludes  to  this  fact. 
Here  we  have  the  most  copious  and  the  most  violent 
whirling  of  the  shattered  liquid;  here  the  most  powerful 
eddies  recoil  against  the  shale.  From  this  portion  of  the 
fall,  indeed,  the  spray  sometimes  rises  wjthout  solution  of 
continuity  to  the  region  of  clouds,  becoming  gradually 
more  attenuated,  and  passing  finally  through  the  condition 
of  true  cloud  into  invisible  vapor,  which  is  sometimes  re- 
precipitated  higher  up.  All  the  phenomena  point  distinctly 
to  the  center  of  the  river  as  the  place  of  greatest  mechanical 
energy,  and  from  the  center  the  vigor  of  the  fall  gradually 
dies  away  toward  the  sides.  The  Horseshoe  form,  with  the 
concavity  facing  downward,  is  an  obvious  and  necessary 
consequence  of  this  action.  Right  along  the  middle  of  the 
river  the  apex  of  the  curve  pushes  its  way  backward,  cut- 
ting along  the  center  a  deep  and  comparatively  narrow 
groove,  and  draining  the  sides  as  it  passes  them.*  Hence 
the  remarkable  discrepancy  between  the  widths  of  the 
Niagara  above  and  below  the  Horseshoe.  All  along  its 
course,  from  Lewiston  Heights  to  its  present  position,  the 
form  of  the  fall  was  probably  that  of  a  horseshoe;  for  this 
is  merely  the  expression  of  the  greater  depth,  and  conse- 
quently greater  excavating  power,  of  the  center  of  (he  river. 
The  gorge,  moreover,  varies  in  width,  as  the  depth  of  the 


*  In  the  discourse  the  excavation  of  the  center  and  drainage  of 
the  sides  action  was  illustrated  by  a  model  devised  by  u«y  assistant, 
Mr.  John  Cottrell. 


152  FRAGMENTS  OF  SCIENCE. 

center  of  the  ancient  river  varied,  being  narrowest  where 
that  depth  was  greatest. 

The  vast  comparative  erosive  energy  of  the  Horseshoe 
Fall  comes  strikingly  into  view  when  it  and  the  American 
Fall  are  compared  together.  The  American  branch  of  the 
river  is  cut  at  a  right  angle  by  the  gorge  of  the  Niagara. 
Here  the  Horseshoe  Fall  was  the  real  excavator.  It  cut 
the  rock,  and  formed  the  precipice,  over  which  the 
American  Fall  tumbles.  But  since  its  formation,  the 
erosive  action  of  the  American  Fall  has  been  almost  nil, 
while  the  Horseshoe  has  cut  its  way  for  500  yards  across 
the  end  of  Goat  Island,  and  is  now  doubling  back  to  exca- 
vate its  channel  parallel  to  the  length  of  the  island.  This 
point,  which  impressed  me  forcibly,  has  not,  I  have  just 
learned,  escaped  the  acute  observation  of  Professor  Ramsay.* 
The  river  bends;  the  Horseshoe  immediately  accommo- 
dates itself  to  the  bending,  and  will  follow  implicitly  the 
direction  of  the  deepest  water  in  the  upper  stream.  The 
flexures  of  the  gorge  are  determined  by  those  of  the  river 
channel  above  it.  -  Were  the  Niagara  center  above  the  fall 
sinuous,  the  gorge  would  obediently  follow  its  sinuosities. 
Once  suggested,  no  doubt  geographers  will  be  able  to  point 
out  many  examples  of  this  action.  The  Zambesi  is  thought 
to  present  a  great  difficulty  to  the  erosion  theory,  because 
of  the  sinuosity  of  the  chasm  below  the  Victoria  Falls. 
But,  assuming  the  basalt  to  be  of  tolerably  uniform  tex- 
ture, had  the  river  been  examined  before  the  formation 
of  this  sinuous  channel,  the  present  zigzag  course  of  the 
gorge  below  the  fall  could,  I  am  persuaded,  have  been 
predicted,  while  the  sounding  of  the  present  river  would 
enable  us  to  predict  the  course  to  be  pursued  by  the  erosion 
in  the  future. 

But  not  only  has  the  Niagara  river  cut  the  gorge;  it  has 
carried  away  the  chips  of  its  own  workshop.  The  shale, 
being  probably  crumbled,  is  easily  carried  away.  But  at 
the  base  of  the  fall  we  find  the  huge  boulders  already  de- 
scribed, and  by  some  means  or  other  these  are  removed 

*  His  words  are:  "  Where  the  body  of  water  is  small  in  the 
American  Fall,  the  edge  has  only  receded  a  few  yards  (where  most 
eroded)  during  the  time  that  the  Canadian  Fall  has  receded  from 
the  north  corner  of  Goat  Island  to  the  innermost  curve  of  the 
Horseshoe  Fall." — Quarterly  Journal  of  Geological  Society,  May, 
18o9. 


^"TL>_- 

^^y^^^o 


- 


154  FRAGMENTS  OF  SCIENCE. 

down  the  river.  The  ice  which  fills  the  gorge  in  winter, 
and  which  grapples  with  the  boulders,  lias  been  regarded 
as  the  transporting  agent.  Probably  it  is  so  to  some  extent. 
But  erosion  acts  without  ceasing  on  the  abutting  points  of 
the  boulders,  thus  withdrawing  their  support  and  urging 
them  gradually  down  the  river.  Solution  also  does  its  por- 
tion of  the  work.  That  solid  matter  is  carried  down  is 
proved  by  the  difference  of  depth  between  the  Niagara 
river  and  Lake  Ontario,  where  the  river  enters  it.  The 
depth  falls  from  72  feet  to  20  feet,  in  consequence  of  the 
deposition  of  solid  matter  caused  by  the  diminished  mo- 
tion of  the  river.* 

The  annexed  highly  instructive  map  has  been  reduced 
from  one  published  in  Mr.  Hall's  "  Geology  of  New  York." 
It  is  based  on  surveys  executed  in  1842,  by  Messrs.  Gibson 
and  Evershed.  The  ragged  edge  of  the  American  Fall 
north  of  Goat  Island  marks  the  amount  of  erosion  which 
it  has  been  able  to  accomplish,  while  the  Horseshoe  Fall 
was  cutting  its  way  southward  across  the  end  of  Goat 
Island  to  its  present  position.  The  American  Fall  is  168 
feet  high,  a  precipice  cut  down,  not  by  itself,  but  by  the 
Horseshoe  Fall.  The  latter  in  1842  was  159  feet  high, 
aud»  as  shown  by  the  map,  is  already  turning  eastward,  to 
excavate  its  gorge  along  the  center  of  the  upper  river,  p 
is  the  apex  of  the  Horseshoe,  and  T  marks  the  site  of  the 
Terrapin  Tower,  with  the  promontory  adjacent,  round 
which  I  was  conducted  by  Couroy.  Probably  since  1842 
the  Horseshoe  has  worked  back  beyond  the  position  here 
assigned  to  it. 

In  conclusion,  we  may  say  a  word  regarding  the  proxi- 
mate future  of  Niagara.  At  the  rate  of  excavation  assigned 
to  it  by  Sir  Charles  Lyell,  namely,  a  foot  a  year,  five 
thousand  years  or  so  will  carry  the  Horseshoe  Fall  far 
higher  than  Goat  Island.  As  the  gorge  recedes  it  will 
drain,  as  it  has  hitherto  done,  the  banks  right  and  left  of 
it,  thus  leaving  a  nearly  level  terrace  between  Goat  Island 
and  the  edge  of  the  gorge.  Higher  np  it  will  totally  drain 
the  American  branch  of  the  river;  the  channel  of  which  in 
due  time  will  become  cultivable  land.  The  American  Fall 

*  Near  the  mouth  of  the  gorge  at  Queenston,  the  depth,  according 
to  the  Admiralty  Chart,  is  ISO  feet-  well  within  the  gorge  it  is  133 
feet. 


THE  PARALLEL  ROADS  OF  GLEN  HOY.          155 

will  then  be  transformed  into  a  dry  precipice,  forming  a 
simple  continuation  of  the  cliffy  boundary  of  the  Niagara 
gorge.  At  the  place  occupied  by  the  fall  at  this  moment 
we  shall  have  the  gorge  enclosing  a  right  angle,  a  second 
whirlpool  being  the  consequence.  To  those  who  visit 
Niagara  a  few  millenniums  hence  I  leave  the  verification 
of  this  prediction.  All  that  can  be  said  is,  that  if  the 
causes  now  in  action  continue  to  act,  it  will  prove  itself 
literally  true 

POSTSCBIPT. 

A  year  or  so  after  I  had  quitted  the  United  States,  a 
man  sixty  years  of  age,  while  engaged  in  painting  one  of 
the  bridges  which  connect  Goat  Island  with  the  Three 
Sisters,  slipped  through  the  rails  of  the  bridge  into  the 
rapids,  and  was  carried  impetuously  toward  the  Horseshoe 
Fall.  He  was  urged  against  a  rock  which  rose  above  the 
water,  and  with  the  grasp  of  desperation  he  clung  to  it. 
The  population  of  the  village  of  Niagara  Falls  was  soon 
upon  the  island,  and  ropes  were  brought,  but  there  was 
none  to  use  them.  In  the  midst  of  the  excitement,  a  tall 
powerful  young  fellow  was  observed  making  his  way  silently 
through  the  crowd.  He  reached  a  rope;  selected  from 
the  bystanders  a  number  of  men,  and  placed  one  end  of 
the  rope  in  their  hands.  The  other  end  he  fastened  round 
himself,  and  choosing  a  point  considerably  above  that  to 
which  the  man  clung,  he  plunged  into  the  rapids.  He 
was  carried  violently  downward,  but  he  caught  the  rocE, 
secured  the  old  painter  and  saved  him.  Newspapers  from 
all  parts  of  the  Union  poured  in  upon  me,  describing  this 
gallant  act  of  my  guide  Conroy. 


CHAPTEK  VIII. 

THE  PARALLEL  ROADS  OF  GLEN  ROY.* 

THE  FIRST  published  allusion  to  the  Parallel  Roads  of 
Glen  Roy  occurs  in  the  appendix  to  the  third  volume  of 
Pennant's  "  Tour  in  Scotland,"  a  work  published  in  1776. 

*  A  discourse  delivered  at  the  Royal  Institution  of  Great  Britain  on 
June  9,  1876. 


156  FRAGMENTS  OP  SCIENCE. 

"  In  the  face  of  these  hills,"  says  this  writer,  "  both  sides 
of  the  glen,  there  are  three  roads  at  small  distances  from 
each  other  and  directly  opposite  on  each  side.  These 
roads  have  been  measured  in  the  complete  parts  of  them, 
and  found  to  be  26  paces  of  a  man  5  feet  10  inches  high. 
The  two  highest  are  pretty  near  each  other,  about  50 
yards,  and  the  lowest  double  that  distance  from  the  near- 
est to  it.  They  are  carried  along  the  sides  of  the  glen  with 
the  utmost  regularity,  nearly  as  exact  as  drawn  with  a  line 
of  rule  and  compass." 

The  correct  heights  of  the  three  roads  of  Glen  Roy  are 
respectively  1,150,  1,070,  and  860  feet  above  the  sea. 
Hence  a  vertical  distance  of  80  feet  separates  the  two  high- 
est, while  the  lowest  road  is  210  feet  below  the  middle 
one. 

These  "  roads"  are  usually  shelves  or  terraces  formed  in 
the  yielding  drift  which  here  covers  the  slopes  of  the 
mountains.  They  are  all  sensibly  horizontal  and  therefore 
parallel.  Pennant  accepted  as  reasonable  the  explanation 
5\A  ,  of  them  given  by  the  country  people  in  his  time.  They 
^  jr  thought  that  the  roads  "  were  designed  for  the  chase,  and 
^^J^  y  that  the  terraces  were  made  after  the  spots  were  cleared  in 
lines  from  wood,  in  order  to  tempt  the  animals  into  the 
open  paths  after  they  were  roused,  in  order  that  they  might 
come  within  reach  of  the  bowmen  who  might  conceal  them- 
selves in  the  woods  above  and  below." 

In  these  attempts  of  "  the  country  people  "we  have  an 
illustration  of  that  impulse  to  which  all  scientific  knowl- 
edge is  due — the  desire  to  know  the  causes  of  things;  and 
'  it  is  a  matter  of  surprise  that  in  the  case  of  the  parallel 
roads,  with  their  weird  appearance  challenging  inquiry, 
-'  this  impulse  did  not  make  itself  more  rapidly  and  energet- 
ically felt.  Their  remoteness  may  perhaps  account  for 
the  fact  that  until  the  year  1817  no  systematic  description 
of  them,  and  no  scientific  attempt  at  an  explanation  of 
them,  appeared.  In  that  year  Dr.  MacCulloch,  who  was 
then  president  of  the  Geological  Society,  presented  to  that 
Society  a  memoir,  in  which  the  roads  were  discussed,  and 
pronounced  to  be  the  margins  of  lakes  once  embosomed  in 
Glen  Roy.  Why  there  should  be  three  roads,  or  why  the 
lakes  should  stand  at  these  particular  levels,  was  left  unex- 
plained. 

To  Dr.  MacCalloch  succeeded  a  mafl,  possibly  not  sq 


THE  PARALLEL  ROADS  OF  GLEN  ROT.    15? 

learned  as  a  geologist,  but  obviously  fitted  by  nature  to 
grapple  with  her  facts  and  to  put  them  in  their  proper  set- 
ting. I  refer  to  Sir  Thomas  Dick-Lauder,  who  presented 
to  the  Royal  Society  of  Edinburgh,  on  the  3d  of  March, 
1818,  his  paper  on  the  Parallel  Roads  of  Glen  Roy.  In  y 
looking  over  the  literature  of  this  subject,  which  is  now 
copious,  it  is  interesting  to  observe  the  differentiation  of  gj.^ 
minds,  and  to  single  out  those  who  went  by  a  kind  of 
instinct  to  the  core  of  the  question,  from  those  who  erred  ••"tJV. 
in  it,  or  who  learnedly  occupied  themselves  with  its  anal- 
ogies, adjuncts,  and  details.  There  is  no  man,  in  my 
opinion,  connected  with  the  history  of  the  subject,  who 
has  shown,  in  relation  to  it,  this  spirit  of  penetration,  this 
force  of  scientific  insight,  more  conspicuously  than  Sir 
Thomas  Dick-Lauder.  Two  distinct  mental  processes  are 
involved  in  the  treatment  of  such  a  question.  Firstly,  the 
faithful  and  sufficient  observation  of  the  data;  and  secondly, 
that  higher  mental  process  in  which  the  constructive  im- 
agination comes  into  play,  connecting  the  separate  facts  of 
observation  witli  their  common  cause,  and  weaving  them 
into  an  organic  whole.  In  neither  of  these  requirements 
did  Sir  Thomas  Dick-Lauder  fail. 

Adjacent  to  Glen  Roy  is  a  valley  called  Glen  Gluoy,  /^  . 
along  the  sides  of  which  ran  a  single  shelf,  or  terrace,  , 
formed  obviously  in  the  same  manner  as  the  parallel  roads 
of  Glen  Roy.  The  two  shelves  on  the  opposing  sides  of  the 
glen  were  at  precisely  the  same  level,  and  Dick-Lauder 
wished  to  see  whether,  and  how,  they  became  united  at  the 
head  of  the  glen.  He  followed  the  shelves  into  the  recesses 
of  the  mountains.  The  bottom  of  the  valley,  as  it  rose, 
came  ever  nearer  to  them,  until  finally,  at  the  head  of  Glen 
Gluoy,  he  reached  a  col,  or  watershed,  of  precisely  the  same 
elevation  as  the  road  which  swept  round  the  glen. 

The  correct  height  of  this  col  is  1,170  feet  above  the 
sea;  that  is  to  say,  20  feet  above  the  highest  road  in 
Glen  Roy. 

From  this  col  a  lateral  branch-valley — Glen  Turrit — led 
down  to  Glen  Roy.  Our  explorer  descended  from  the  col 
to  the  highest  road  of  the  latter  glen,  and  pursued  it  exactly 
as  he  had  pursued  the  road  in  Glen  Gluoy.  For  a  time  it 
belted  the  mountain  sides  at  a  considerable  height  above 
the  bottom  of  the  valley;  but  this  rose  as  he  proceeded, 
coming  ever  nearer  to  the  highest  shelf,  until  finally  he 


158 


FRAGMENTS  OF  SCIENCE. 


reached  a  col,  or  watershed,  looking  into  Glen  Spey,  and 
of  precisely  the  same  elevation  as  the  highest  road  of 
Glen  Roy. 

He  then  dropped  down  to  the  lowest  of  these  roads,  and 
.  "  followed  it  toward  the  mouth  of  the  glen.  Its  elevation 
above  the  bottom  of  the  valley  gradually  increased;  not  be- 
cause the  shelf  rose,  but  because  it  remained  level  while 
the  valley  sloped  downward.  He  found  this  lowest  road 
doubling  round  the  hills  at  the  mouth  of  Glen  Roy,  and 


PARALLEL  ROADS  OF  GLEN    ROY. 
After  a  Sketch  by  SIR  THOMAS  DICK-LAUDER. 

running  along  the  sides  of  the  mountains  which  flank 
Glen  Spean.  He  followed  it  eastward.  The  bottom  of 
the  Spean  Valley,  like  the  others,  gradually  rose,  and 
therefore  gradually  approached  the  road  on  the  adjacent 
mountain-side.  He  came  to  Loch  Laggan,  the  surface  of 
which  rose  almost  to  the  level  of  the 'road,  and  beyond  the 
head  of  this  lake  he  found,  as  in  the  other  two  cases,  a 
col,  or  watershed,  at  Makul,  of  exactly  the  same  level  as 
the  single  road  in  Glen  Spean,  which,  it  will  be  remembered, 
is  a  continuation  of  the  lowest  road  in  Glen  Roy. 


160  *& A  GMEXTS  0  V  SCIENCE. 

Here  w6  have  a  series  of  facts  of  obvious  significance  as 
regards  the  solution  of  this  problem.  The  effort  of  the 
mind  to  form  a  coherent  image  from  such  facts  may  be 
compared  with  the  effort  of  the  eyes  to  cause  the  pictures 
of  a  stereoscope  to  coalesce.  For  a  time  we  exercise  a 
-  certain  strain,  the  object  remaining  vague  and  indistinct. 
Suddenly  its  various  parts  seem  to  run  together,  the  object 
starting  forth  in  clear  and  definite  relief.  Such,  I  take  it, 
was  the  effect  of  his  ponderings  upon  the  mind  of  Sir 
Thomas  Dick-Lauder.  His  solution  was  this:  Taking  all 
their  features  into  account,  he  was  convinced  that  water 
only  could  have  produced  the  ten-aces.  But  how  had  the 
water  been  collected?  He  saw  clearly  that,  supposing  the 
mouth  of  Glen  Gluoy  to  be  stopped  by  a  barrier  sufficiently 
high,  if  the  waters  from  the  mountains  flanking  the  glen 
were  allowed  to  collect,  they  would  form  behind  the 
barrier  a  lake,  the  surface  of  which  would  gradually  rise 
until  it  reached  the  level  of  the  col  at  the  head  of  the  glen. 
The  rising  would  then  cease;  the  superfluous  water  of  Glen 
Gluoy  discharging  itself  over  the  col  into  Glen  Roy.  As 
long  as  the  barrier  stopping  the  mouth  of  Glen  Gluoy  con- 
tinued high  enough,  we  should  have  in  that  glen  a  lake  at 
the  precise  level  of  its  shelf,  which  lake,  acting  upon  the 
loose  drift  of  the  flanking  mountains,  would  form  the  shelf 
revealed  by  observation. 

So  much  for  Glen  Gluoy.  But  suppose  the  mouth  of 
Glen  Roy  also  stopped  by  a  similar  barrier.  Behind  it  also 
the  water  from  the  adjacent  mountains  would  collect.  The 
surface  of  the  lake  thus  formed  would  gradually  rise,  until 
it  had  reached  the  level  of  the  col  which  divides  Glen  Roy 
from  Glen  Spey.  Here  the  rising  of  the  lake  would  cease; 
its  superabundant  water  being  poured  over  the  col  into  the 
valley  of  the  Spey.  This  state  of  things  would  continue  as 
long  as  a  sufficiently  high  barrier  remained  at  the  mouth  of 
Glen  Roy.  The  lake  thus  dammed  in  with  its  surface  at 
the  level  of  the  highest  parallel  road,  would  act,  as  in  Glen 
Gluoy,  upon  the  friable  drift  overspreading  the  mountains, 
and  would  form  the  highest  road  or  terrace  of  Glen  Roy. 
.  And  now  let  us  suppose  the  barrier  to  be  so  far  removed 
from  the  mouth  of  Glen  Roy  as  to  establish  a  connection 
between  it  and  the  upper  part  of  Glen  Spean,  while  the 
lower  part  of  the  latter" glen  still  continued  to  be  blocked 
up.  Upper  Glen  Spean  and  Glen  Roy  would  then  be  oc- 


THE  PARALLEL  ROADS  OF  GLEN  ROT.          161 

cupied  by  a  continuous  lake,  the  level  of  which  would 
obviously  be  determined  by  the  col  at  the  head  of  Loch 
Laggan.  The  water  in  Glen  Roy  would  sink  from  the  level 
it  had  previously  maintained,  to  the  level  of  its  new  place 
of  escape.  This  new  lake-surface  would  correspond  exactly 
with  the  lowest  parallel  road,  and  it  would  form  that  road 
by  its  action  upon  the  drift  of  the  adjacent  mountains. 

In  presence  of  the  observed  facts,  this  solution  commends 
itself  strongly  to  the  scientific  mind.  The  question  next  ^ 
occurs,  What  was  the  character  of  the  assumed  barrier 
which  stopped  the  glens?  There  are  at  the  present  -r-v^ 
moment  vast  masses  of  detritus  in  certain  portions  of  Glen 
Spean,  and  of  such  deTrTtus  Sir  Thomas  Dick-Lauder 
imagined  his  barriers  to  have  been  formed.  By  some  un- 
known convulsion,  this  detritus  had  been  heaped  up. 
But,  once  given,  and  once  granted  that  it  was  subsequently 
removed  in  the  manner  indicated,  the  single  road  of  Glen 
Gluoy  and  the  highest  and  lowest  roads  of  Glen  Roy,  would 
be  explained  in  a  satisfactory  manner. 

To  account  for  the  second  or  middle  road  of  Glen  Roy,  ~ 
Sir  Thomas  Dick-Lauder  invoked  a  new  agency.  He  sup- 
posed that  at  a  certain  point  in  the  breaking  down  or 
waste  of  his  dam,  a  halt  occurred,  the  barrier  holding  its 
ground  at  a  particular  level  sufficiently  long  to  dam  a  lake 
rising  to  the  height  of,  and  forming  the  second  road.  This 
point  of  weakness  was  at  once  detected  by  Mr.  Darwin,  and^ 
adduced  by  him  as  proving  that  the  levels  of  the  cols  did 
not  constitute  an  essential  feature  in  the  phenomena  of  the  '-<-j^  ; 
parallel  roads.  Though  not  destroyed,  Sir  Thomas  Dick- 
Lauder's  theory  was  seriously  shaken  by  this  argument,  '^4^ 
and  it  became  a  point  of  capital  importance,  if  the  facts 
permitted,  to  remove  such  source  of  weakness.  This  was 
done  in  1847  by  Mr.  David  Milne,  now  Mr.  Milne-Home. 
On  walking  up  Glen  Roy  from  Roy  Bridge,  we  pass  the 
mouth  of  a  lateral  glen,  called  Glen  Glaster,  running  east- 
ward from  Glen  Roy.  There  is  nothing  in  this  lateral  glen 
to  attract  attention,  or  to  suggest  that  it  could  have  any 
conspicuous  influence  in  the  production  of  the  parallel 
roads.  Hence,  probably,  the  failure  of  Sir  Thomas  Dick- 
Lauder  to  notice  it.  But  Mr.  Milne-Home  entered  this 
glen,  on  the  northern  side  of  which  the  middle  and  lowest 
roads  are  fairly  shown.  The  principal  stream  running 
through  the  glen  turns  at  a  certain  point  northward  and 


16*1  FRAGMENTS  OF  SCIENCE. 

loses  itself  among  the  hills  too  high  to  offer  any  outlet.  But 
another  branch  of  the  glen  turns  to  the  southeast;  and, 
following  up  this  branch,  Mr.  Milne-Home  reached  a  col, 
or  watershed,  of  the  precise  level  of  the  second  Glen  Roy 
road.  When  the  barrier  blocking  the  glens  had  been  so 
far  removed  as  to  open  this  col,  the  water  in  Glen  Roy 
would  sink  to  the  level  of  the  second  road.  A  new  lake  of 
diminished  depth  would  be  thus  formed,  the  surplus  water  of 
which  would  escape  over  the  Gleu  Glaster  col  into  Glen 
Spean.  The  margin  of  this  new  lake,  acting  upon  the  dc- 
trital  matter,  would  form  the  second  road.  The  theory  of 
Sir  Thomas  Dick-Lauder,  as  regards  the  part  played  by 
the  cols,  was  re-riveted  by  this  new  and  unexpected  dis- 
covery. 

I  have  referred  to  Mr.  Darwin,  whose  powerful  mind 
swayed  for  a  time  the  convictions  of  the  scientific  world  in 
relation  to  this  question.  His  notion  was — and  it  is  a 
notion  which  very  naturally  presents  itself — that  the  par- 
allel roads  were  formed  by  the  sea;  that  this  whole  region 
was  once  submerged  and  subsequently  upheaved;  that  there 
were  pauses  in  the  process  of  upheaval,  during  which  these 
glens  constituted  so  many  fiords,  on  the  sides  of  which  the 
parallel  terraces  were  formed.  This  theory  will  not  bear 
close  criticism;  nor  is  it  now  maintained  by  Mr.  Darwin 
himself.  It  would  not  account  for  the  sea  being  20 feet 
higher  in  Glen  Gluoy  than  in  Glen  Roy.  It  would  not  ac- 
count for  the  absence  of  the  second  and  third  Glen  Roy 
roads  from  Glen  Gluoy,  where  the  mountain  flanks_are 
quite  as  impressionable  as  in  Glen  Roy.  It  would  not  ac- 
count for  the  absence  of  the  shelves  from  the  other  moun- 
tains in  the  neighborhood,  all  of  which  would  have  been 
clasped  by  the  sea  had  the  sea  been  there.  Here  then,  and 
no  doubt  elsewhere,  Mr.  Darwin  has  shown  himself  to  be 
fallible;  but  here;  as  elsewhere,  he  has  shown  himself  equal 
to  that  discipline  of  surrender  to  evidence  which  girds  his 
intellect  with  such  unassailable  moral  strength. 

But,  granting  the  significance  of  Sir  Thomas  Dick- 
Lauder's  facts,  and  the  reasonableness,  on  the  whole,  of 
the  views  which  he  has  founded  on  them,  they  will  not 
bear  examination  in  detail.  No  such  barriers  of  detritus  as 
he  assumed  could  have  existed  without  leaving  traces  be- 
hind them;  but  there  is  no  trace  left.  There  is  detritus 
enough  in  Glen  Spean,  but  not  where  it  is  wanted.  The 

I 


THK  PARALLEL  ROADS  OF  OLEN  ROT.          163 

two  highest  parallel  roads  stop  abruptly  at  different  points  >^, 
near  the  mouth  of  Glen  Roy,  but  no  remnant  of  the  barrier 
against  which  they  abutted  is  to  be  seen.  It  might  be  urged 
that  the  subsequent  invasion  of  the  valley  by  glaciers  has 
swept  the  detritus  away;  but  there  have  been  no  glaciers  in 
these  valleys  since  the  disappearance  of  the  lakes  Profes- 
sor Geikie  has  favored  me  with  a  drawing  of  Glen  Spean 
"road"  near  the  entrance  to  Glen  Trieg.  The  road  forms 
a  shelf  round  a  great  mound  of  detritus  which,  had  a 
glacier  followed  the  formation  of  the  shelf,  must  have  been 
cleared  away.  Taking  all  the  circumstances  into  account, 
you  may,  I  think,  with  safety  dismiss  the  detrital  barrier  as 
incompetent  to  account  for  the  present  condition  of  Glen 
Gluoy  and  Glen  Roy. 

Hypotheses  in  science,  though  apparently  transcending 
experience,  are  in  reality  experience  modified  by  scientific 
thought  and  pushed  into  an  ultra  experiential  region.  At 
the  time  that  he  wrote,  Sir  Thomas  Dick-Lauder  could  not 
possibly  have  discerned  the  cause  subsequently  assigned  for 
the  blockage  of  these  glens.  A  knowledge  of  the  action  of 
ancient  glaciers  was  the  necessary  antecedent  to  the  new  ^~V/ 
explanation,  and  experience  of  this  nature  was  not  pos- 
sessed by  the  distinguished  writer  just  mentioned.  The 
extension  of  Swiss  glaciers  far  beyond  their  present  limits, 
was  first  made  known  by  a  Swiss  engineer  named  Venetz, 
who  established,  by  the  marks  they  had  left  behind  them, 
their  former  existence  in  places  which  they  had  longforsaken. 
The  subject  of  glacier  extension  was  subsequently  followed 
up  with  distinguished  success  by  Oharpentier,  Studer,  and 
others.  With  characteristic  vigor  Agassiz  grappled  with  it, 
extending  his  observations  far  beyond  the  domain  of  Switz- 
erland. He  came  to  this  country  in  1840,  and  found  in 
various  places  indubitable  marks  of  ancient  glacier  action. 
England,  Scotland,  Wales,  and  Ireland  he  proved  to  have 
once  given  birth  to  glaciers.  He  visited  Glen  Roy,  surveyed 
the  surrounding  neighborhood,  and  pronounced,  as  a  conse- 
quence of  his  investigation,  the  barriers  which  stopped  the 
glens  and  produced  the  parallel  roads  to  have  been  barriers 
of  ice.  To  Mr.  Jarnieson,  above  all  others,  we  are  indebted 
for  the  thorough  testing  and  confirmation  of  this  theory. 

And  let  me  here  say  that  Agassiz  is  only  too  likely  to  be 
misrated  and  misjudged  by  those  who,  though  accurate 
within  a  limited  sphere,  fail  to  grasp  in  their  totality  the. 


164  FRAGMENTS  OF  SCIENCE. 

motive  powers  invoked  in  scientific  investigation.  True  he 
lacked  mechanical  precision,  but  he  abounded  in  that  force 
and  freshness  of  the  scientific  imagination  which  in  some 
^ /•/  sciences,  and  probably  in  some  stages  of  all  sciences,  are 
essential  to  the  creator  of  knowledge.  To  Agassiz  was 
given,  not  the  art  of  the  refiner,  but  the  instinct  of  the  dis- 
coverer, and  the  strength  of  the  delver  who  brings  ore  from 
the  recesses  of  the  mine.  That  ore  may  contain  its  share 
of  dross,  but  it  also  contains  the  precious  metal  which 
gives  employment  to  the  refiner,  and  without  which  his 
occupation  would  depart. 

Let  us  dwell  for  a  moment  upon  this  subject  of  ancient 
glaciers.  Under  a  flask  containing  water,  in  which  a  ther- 
^r  mometer  is  immersed,  is  placed  a  Bunsen's  lamp.  The  water 
'..  yis  heated,  reaches  a  temperature  of  212  degrees,  and  then  be- 
gins to  boil.  The  rise  of  the  thermometer  then  ceases,  al- 
though heat  continues  to  be  poured  by  the  lamp  into  the 
water.  What  becomes  of  that  heat?  We  know  that  it  is  con- 
sumed in  the  molecular  work  of  vaporization.  In  the  exper- 
iment here  arranged,  the  steam  passes  from  the  flask  through 
a  tube  into  a  second  vessel  kept  at  a  low  temperature.  Here 
it  is  condensed,  and  indeed  congealed  to  ice,  the  second 
vessel  being  plunged  in  a  mixture  cold  enough  to  freeze  the 
water.  As  a  result  of  the  process  we  obtain  a  mass  of  ice. 
That  ice  has  an  origin  very  antithetical  to  its  own  char- 
acter. Though  cold,  it  is  the  child  of  heat.  If  we  re- 
moved the  lamp,  there  would  be  no  steam,  and  if  there 
'vere  no  steam  there  would  be  no  ice.  The  mere  cold  of  the 
mixture  surrounding  the  second  vessel  would  not  produce 
ice.  The  cold  must  have  the  proper  material  to  work  upon; 
and  this  material — aqueous  vapor — is,  as  we  here  see,  the 
direct  product  of  heat. 

It  is  now,  I  suppose,  fifteen  or  sixteen  years  since  I 
found  myself  conversing  with  an  illustrious  philosopher 
regarding  that  glacial  epoch  which  the  researches  of 
Agassiz  and  others  had  revealed.  This  profoundly  thought- 
ful man  maintained  the  fixed  opinion  that,  at  a  certain 
stage  in  the  history  of  the  solar  system,  the  sun's  radiation 
had  suffered  diminution,  the  glacial  epoch  being  a  conse- 
quence of  this  solar  chill.  The  celebrated  French  math- 
ematician Poisson  had  another  theory.  Astronomers 
have  shown  that  the  solar  system  moves  through  space, 
and  "the  temperature  of  space"  is  a  familiar  expression 


THE  PARALLEL  ROADS  OF  GLEN  ROY.         165 

with  scientific  men.  It  was  considered  probable  by  Poisson 
that  our  system,  during  its  motion,  had  traversed  portions  '  <^£«, 
of  space  of  different  temperatures;  and  that,  during  its 4?  j£, 
passage  through  one  of  the  colder  regions  of  the  universe, 
the  glacial  epoch  occurred.  Notions  such  as  these  were 
more  or  less  current  everywhere  not  many  years  ago,  and  I 
therefore  thought  it  worth  while  to  show  how  incomplete 
they  were.  Suppose  the  temperature  of  our  planet  to  be 
reduced,  by  the  subsidence  of  solar  heat,  the  cold  of  space, 
or  any  other  cause,  say  one  hundred  degrees.  Four-and- 
twenty  hours  of  such  a  chill  would  bring  down  as  snow 
nearly  all  the  moisture  of  our  atmosphere.  But  this 
would  not  produce  a  glacial  epoch.  Such  an  epoch  would 
require  the  long-continued  generation  of  the  material  from 
which  the  ice  of  glaciers  is  derived.  Mountain  snow,  the 
nutriment  of  glaciers,  is  derived  from  aqueous  vapor  raised 
mainly  from  the  tropical  ocean  by  the  sun.  The  solar  fire 
is  as  necessary  a  factor  in  the  process  as  our  lamp  in  the 
experiment  referred  to  a  moment  ago.  Nothing  is  easier 
than  to  calculate  the  exact  amount  of  heat  expended  by  the 
sun  in  the  production  of  a  glacier.  It  would,  as  I  have 
elsewhere  shown,*  raise  a  quantity  of  cast  iron  five  times 
the  weight  of  the  glacier  not  only  to  a  white  heat,  but  to 
its  point  of  fusion.  If,  as  I  have  already  urged,  instead  of 
being  filled  with  ice,  the  valleys  of  the  Alps  were  filled 
with  white-hot  metal,  of  quintuple  the  mass  of  the  present 
glaciers,  it  is  the  heat  and  not  the  cold,  that  would  arrest 
our  attention  and  solicit  our  explanation.  The  process  of 
glacier  making  is  obviously  one  of  distillation,  in  which 
the  fire  of  the  sun,  which  generates  the  vapor,  plays  as 
essential  a  part  as  the  cold  of  the  mountains  which  con- 
denses it.f 

It  was  their  ascription  to  glacier  action  that  first  gave 
the  parallel  roads  of  Glen  Koy  an  interest  in  my  eyes;  and 
in  1867,  with  a  view  to  self-instruction,  I  made  a  solitary 

*"Heata  Mode  of  Motion,"  fifth  edition,  chap,  vi.:  Forms  of 
Water,  §§  55  and  56. 

fin  Lyell's  excellent  "  Principles  of  Geology,"  the  remark  occurs 
that  "  several  writers  have  fallen  into  the  strange  error  of  supposing 
that  the  glacial  period  must  have  been  one  of  higher  ruean  temper- 
ature than  usual."  The  really  strange  error  was  the  forgetfulness 
of  the  fact  that  without  the  heat  the  substance  necessary  to  the 
production  of  glaciers  would  be  wanting. 


166  FRAGMENTS  OF  SCIENCE. 

pilgrimage  to  the  place,  and  explored  pretty  thoroughly 
the  roads  of  the  principal  glen.  I  traced  the  highest  road 
to  the  col  dividing  Glen  Roy  from  Glen  Spey,  and,  thanks 
to  the  civility  of  an  ordnance  surveyor,  I  was  enabled  to 
inspect  some  of  the  roads  with  4  theodolite,  and  to  satisfy 
myself  regarding  the  common  level  of  the  shelves  at  op- 
posite sides  of  the  valley.  As  stated  by  Pennant,  the 
width  of  the  roads  amounts  sometimes  to  more  than  twenty 
yards;  but  near  the  head  of  Grlen  Roy  the  highest  road 
ceases  to  have  any  width,  for  it  runs  along  the  face  of  a 
rock,  the  effect  of  the  lapping  of  the  water  on  the  more 
friable  portions  of  the  rock  being  perfectly  distinct  to  this 
hour.  My  knowledge  of  the  region  was,  however,  far  from 
complete,  and  nine  years  had  dimmed  the  memory  even  of 
the  portion  which  had  been  thoroughly  examined.  Hence 
my  desire  to  see  the  roads  once  more  before  venturing  to 
talk  to  you  about  them.  The  Easter  holidays  of  1876  were 
to  be  devoted  to  this  purpose;  but  at  the  last  moment  a 
telegram  from  Roy  Bridge  informed  me  that  the  roads 
were  snowed  up.  Finding  books  and  memories  poor  sub- 
stitutes for  the  flavor  of  facts,  I  resolved  subsequently 
to  make  another  effort  to  see  the  roads.  Accordingly  last 
Thursday  fortnight,  after  lecturing  here,  I  packed  up, 
and  started  (not  this  time  alone)  for  the  North.  Next 
day  at  noon  my  wife  and  I  found  ourselves  at  Dalwhinnie, 
whence  a  drive  of  some  five-and-thirty  miles  brought  us 
to  the  excellent  hostelry  of  Mr.  Macintosh,  at  the  mouth 
of  Glen  Roy. 

We  might  have  found  the  hills  covered  with  mist, 
which  would  have  wholly  defeated  us;  but  Nature  was 
good-natured,  and  we  had  two  successful  working  days 
among  the  hills.  Guided  by  the  excellent  ordnance  map 
of  the  region,  on  the  Saturday  morning  we  went  up  the 
glen,  and  on  reaching  the  stream  called  Allt  Bhreac 
Achaidh  faced  the  hills  to  the  west.  At  the  watershed  be- 
tween Glen  Roy  and  Glen  Fintaig  we  bore  northward, 
struck  the  ridge  above  Glen  Gluoy,  came  in  view  of  its 
road,  which  we  persistently  followed  as  long  as  it  continued 
visible.  It  is  a  feature  of  all  the  roads  that  they  vanish 
before  reaching  the  cols  over  which  fell  the  waters  of  the 
lakes  which  formed  them.  One  reason  doubtless  is  that 
at  their  upper  ends  the  lakes  were  shallow,  and  incompe- 
tent on  this  account  to  raise  wavelets  of  any  strength  to 


THE  PARALLEL  ROADS  OF  GLEN-  ROY.       167 

act  upon  the  mountain  drift.  A  second  reason  is  that 
they  were  laud-locked  in  the  higher  portions  and  protected 
from  the  southwesterly  winds,  the  stillness  of  their  waters 
causing  them  to  produce  but  a  feeble  impression  upon  the 
mountain  sides.  From  Glen  Gluoy  we  passed  down  Glen 
Turrit  to  Glen  Roy,  and  through  it  homeward,  thus 
accomplishing  two  or  three  and  twenty  miles  of  rough  and 
honest  work. 

Next  day  we  thoroughly  explored  Glen  Glaster,  following 
its  two  roads  as  far  as  they  were  visible.  We  reached  the 
col  discovered  by  Mr.  Milne-Home,  which  stands  at  the 
level  of  the  middle  road  of  Glen  Roy.  Thence  we  crossed 
southward  over  the  mountain  Creag  Dliubli,  and  examined 
the  erratic  blocks  upon  its  sides,  and  the  ridges  and - 
mounds  of  moraine  matter  which  cumber  the  lower  flanks 
of  the  mountain.  The  observations  of  Mr.  Jamieson  upon' 
this  region,  including  the  mouth  of  Glen  Trieg,  are  in  the 
highest  degree  interesting.  We  entered  Glen  Spean,  and 
continued  a  search  begun  on  the  evening  of  our  arrival  at 
Roy  Bridge — the  search,  namely,  for  glacier  polishings 
and  markings.  We  did  not  find  them  copious,  but  they 
are  indubitable.  One  of  the  proofs  most  convenient  for 
reference,  is  a  great  rounded  rock  by  the  roadside,  1,000 
yards  east  of  the  milestone  marked  three-quarters  of  a  mile 
from  Roy  Bridge.  Farther  east  other  cases  occur,  and 
they  leave  no  doubt  upon  the  mind  that  Glen  Spean  was 
at  one  time  filled  by  a  great  glacier.  To  the  disciplined 
eye  the  aspect  of  the  mountains  is  perfectly  conclusive  on 
this  point;  and  in  no  position  can  the  observer  more  readily 
and  thoroughly  convince  himself  of  this  than  at  the  head 
of  Glen  Glaster.  The  dominant  hills  here  are  all  intensely 
glaciated. 

But  the  great  collecting  ground  of  the  glaciers  which 
dammed  the  glens  and  produced  the  parallel  roads,  were  the  *^- 
mountains  south  and  west  of  Glen  Spean.  The  monarch 
of  these  is  Ben  Nevis,  4,370  feet  high.  The  position  of 
Ben  Nevis  and  his  colleagues,  in  reference  to  the  vapor- 
laden  winds  of  the  Atlantic,  is  a  point  of  the  first  impor- 
tance. It  is  exactly  similar  to  that  of  Carrantual  and  the 
Macgillicuddy  Reeks  in  the  southwest  of  Ireland.  These 
mountains  are,  and  were,  the  first  to  encounter  the  south- 
western Atlantic  winds,  and  the  precipitation,  even  at 
present,  in  the  neighborhood  of  Killaruey,  is  enormous. 


163  FKAGMKNTS  OP  SCIENCE. 

The  winds,  robbed  of  their  vapor,  and  charged  with  the 
heat  set  free  by  its  precipitation,  pursue  their  direction 
obliquely  across  Ireland;  and  the  effect  of  the  drying  proc- 
ess rnav  be  understood  by  comparing  the  rainfall  at 
Cahirciveen  with  that  at  Portarlington.  As  found  by  Dr. 
Lloyd,  the  ratio  is  as  59  to  21 — fifty-nine  inches  annually 
at  Cahirciveen  to  twenty-one  at  Portarlington.  During 
the  glacial  epoch  this  vapor  fell  as  snow,  and  the  conse- 
quence was  a  system  of  glaciers  which  have  left  traces  and 
evidences  of  the  most  impressive  character  in  the  region  of 
the  Killarney  lakes.  I  have  referred  in  other  places  to 
the  great  glacier  which,  descending  from  the  Reeks,  moved 
through  the  Black  Valley,  took  possession  of  the  lake-basins, 
and  left  its  traces  on  every  rock  and  island  emergent  from 
the  waters  of  the  upper  lake.  They  are  all  conspicuously 
glaciated.  Not  in  Switzerland  itself  do  we  find  clearer 
traces  of  ancient  glacier  action. 

What  the  Macgillicuddy  Reeks  did  in  Ireland,  Ben  Nevis 
and  the  adjacent  mountains  did,  and  continue  to  do,  in 
Scotland.  We  had  an  example  of  this  on  the  morning  we 
quitted  Roy  Bridge.  From  the  bridge  westward  rain  fell 
copiously,  and  the  roads  were  wet;  but  the  precipitation 
ceased  near  Loch  Laggan,  whence  eastward  the  roads  were 
dry.  Measured  by  the  gauge,  the  rainfall  at  Fort  William 
is  86  inches,  while  at  Laggan  it  is  only  46  inches  annually. 
The  difference  between  west  and  east  is  forcibly  brought 
out  by  observations  at  the  two  ends  of  the  Caledonian 
canal.  Fort  William  at  the  southwestern  end  has,  as  just 
stated,  86  inches,  while  Ctilloden,  at  its  northeastern  end, 
has  only  24.  To  the  researches  of  that  able  and  accom- 
plished meteorologist,  Mr.  Buchan,  we  are  indebted  for 
these  and  other  data  of  the  most  interesting  and  valuable 
kind. 

Adhering  to  the  facts  now  presented  to  us,  it  is  not  dif- 
ficult to  restore  in  idea  the  process  by  which  the  glaciers  of 
Lochaber  were   produced   and    the  glens  dammed  by  ice. 
When  the  cold  of  the  glacial  epoch  began   to  invade   the 
Scottish  hills,  the  sun  at  the  same  time  acting  with  suffi- 
ient  power  upon  the  tropical  ocean,  the  vapors  raised  and 
i rifted  on  to  these  northern  mountains  were  more  and  more 
converted  into  snow.     This  slid  down  the  slopes,  and  from 
every  valley,  strath,  and  corry,  south  of  Glen  Spean,  glaciers 
were  poured  into"  that  glen.     The  two  great  factors  here 


I 


THE  PARALLEL  ROADS  OF  GLEN  ROT.         169 

brought  into  play  are  the  nutrition  of  the  glaciers  by  the 
frozen  material  above,  and  their  consumption  in  the  milder 
air  below.  For  a  period  supply  exceeded  consumption,  and 
the  ice  extended,  tilling  Glen  Speau  to  an  ever-increasing 
height,  and  abutting  against  the  mountains  to  the  north 
of  that  glen.  But  why,  it  may  be  asked,  should  the  val- 
leys south  of  Glen  Spean  be  receptacles  of  ice  at  a  time 
when  those  north  of  it  were  receptacles  of  water?  The 
answer  is  to  be  found  in  the  position  and  the  greater  eleva- 
tion of  the  mountains  south  of  Glen  Speau.  They  first 
received  the  loads  of  moisture  carried  by  the  Atlantic  winds, 
and  not  until  they  had  been  in  part  dried,  and  also  warmed 
by  the  liberation  of  their  latent  heat,  did  these  winds  touch 
the  hills  north  of  the  Glen. 

An  instructive  observation  bearing  upon  this  point  is 
here  to  be  noted.  Had  our  visit  been  in  the  winter  we 
should  have  found  all  the  mountains  covered;  had  it  been  / 
in  the  summer  we  should  have  found  the  snow  all  gone. 
But  happily  it  was  at  a  season  when  the  aspect  of  the 
mountains  north  and  south  of  Glen  Spean  exhibited  their 
relative  powers  as  snow  collectors.  Scanning  the  former 
hills  from  many  points  of  view,  we  were  hardly  able  to 
detect  a  -fleck  of  snow,  while  heavy  swaths  and  patches  /L4L, 
loaded  the  latter.  Were  the  glacial  epoch  to  return,  the 
relation  indicated  by  this  observation  would  cause  Glen 
Spean  to  be  filled  with  glaciers  from  the  south,  while  the 
hills  and  valleys  on  the  north,  visited  by  warmer  and  drier 
winds,  would  remain  comparatively  free  from  ice.  This 
flow  from  the  south  would  be  reinforced  from  the  west,  and 
as  long  as  the  supply  was  in  excess  of  the  consumption  the 
glaciers  would  extend,  the  dams  which  closed  the  glens 
increasing  in  height.  By  and  by  supply  and  consumption 
becoming  approximately  equal,  the  height  of  the  glacier 
barriers  would  remain  constant.  Then,  if  milder  weather 
set  in,  consumption  would  be  in  excess,  a  lowering  of  the 
barriers  and  a  retreat  of  the  ice  being  the  consequence. 
But  for  a  long  time  the  conflict  between  supply  and  con- 
sumption would  continue,  retarding  indefinitely  the  dis- 
appearance of  the  barriers,  and  keeping  the  imprisoned 
lakes  in  the  northern  glens.  But  however  slow  its  retreat, 
the  ice  in  the  long  run  would  be  forced  to  yield.  The  dam 
at  the  mouth  of  Glen  Eoy,  which  probably  entered  the 
glen  sufficiently  far  to  block  up  Glen  Glaster,  would  gradu- 


170  FRAGMENTS  OF  SCIENCE. 

ally  retreat.  Glen  Glaster  and  its  col  being  opened,  the 
subsidence  of  the  lake  eighty  feet,  from  the  level  of  the 
highest  to  that  of  the  second  parallel  road,  would  follow  as 
a  consequence.  I  think  this  the  most  probable  course  of 
things,  but  it  is  also  possible  that  Glen  Glaster  may  have 
been  blocked  by  a  glacier  from  Glen  Trieg.  The  ice 
dam  continuing  to  retreat,  at  length  permitted  Glen  Roy 
to  connect  itself  with  upper  Glen  Spean.  A  continuous 
lake  then  filled  both  the  glens,  the  level  of  which,  as  already 
explained,  was  determined  by  the  col  at  Makul,  above  the 
head  of  Loch  Laggan.  The  last  to  yield  was  the  portion 
of  the  glacier  which  derived  nutrition  from  Ben  Nevis, 
and  probably  also  from  the  mountains  north  and  south  of 
Loch  Arkaig.  But  it  at  length  yielded,  and  the  waters  in 
the  glens  resumed  the  courses  which  they  pursue  to-day. 

For  the  removal  of  the  ice  barriers  no  cataclysm  is  to  be 
invoked;  the  gradual  melting  of  the  darfTwouTd  produce 
the  entire  series  of  phenomena.  In  sinking  from  col  to 
col  the  water  would  flow  over  a  gradually  melting  barrier, 
AjU-  .the  surface  of  the  imprisoned  lake  not  remaining  sufficiently 
long  at  any  particular  level  to  produce  a  shelf  comparable 
to  the  parallel  roads.  By  temporary  halts  in  the  process  of 
melting  due  to  atmospheric  conditions  or  to  the  character 
of  the  dam  itself,  or  through  local  softness  in  the  drift, 
small  pseudo-terraces  would  be  formed  which,  to  the  per- 
plexity of  some  observers,  are  seen  upon  the  flanks  of  the 
glens  to-day. 

In  presence  then  of  the  fact  that  the  barriers  which 
stopped  these  glens  to  a  height,  it  may  be,  of  1,500  feet 
above  the  bottom  of  Glen  Spean,  have  dissolved  and  left 
not  a  wreck  behind;  in  presence  of  the  fact,  insisted  on  by 
Professor  Geikie,  that  barriers  of  detritus  would  un- 
doubtedly have  been  able  to  maintain  themselves  had  they 
ever  been  there;  in  presence  of  the  fact  that  great  glaciers 
once  most  certainly  filled  these  valleys — that  the  whole 
region,  as  proved  by  Mr.  Jamieson,  is  filled  with  the  traces 
of  their  action;  the  theory  which  ascribes  the  parallel 
roads  to  lakes  dammed  by  barriers  of  ice  has,  in  my 
opinion,  a  degree  of  probability  on  its  side  which  amounts 
to  a  practical  demonstration  of  its  truth. 

Into  the  details  of  the  terrace  formation  I  do  not  enter. 
Mr.  Darwin  and  Mr.  Jamieson  on  the  one  side,  and  Sir 
John  Lubbock  on  the  other,  deal  with  true  causes  The 


THE  PARALLEL  ROADS  OF  GLEN  ROT.          171 

terraces,  no  doubt,  are  due  in  part  to  the  descending  drift 
arrested  by  the  water,  and  in  part  to  the  fretting  of  the 
wavelets,  and  the  rearrangement  of  the  stirred  detritus, 
along  the  belts  of  contact  of  lake  and  hill.  The  descent  of 
matter  must  have  been  frequent  when  the  drift  was  un- 
bound by  the  rootlets  which  hold  it  together  now.  In 
some  cases,  it  may  be  remarked,  the  visibility  of  the  roads 
is  materially  augmented  by  differences  of  vegetation.  The 
grass  upon  the  terraces  is  not  always  of  the  same  character 
as  that  above  and  below  them,  while  on  heather-covered 
hills  the  absence  of  the  dark  shrub  from  the  roads  greatly 
enhances  their  conspicuousness. 

The  annexed  sketch  of  a  model  (p.  173)  will  enable  the   ^ 
reader  to  grasp  the  essential  features  of  the  problem  and    J 
its  solution.     Glen  Gluoy  and  Glen  Roy  are  lateral  valleys 
which  open  into  Glen  Spean.     Let  us  suppose  Glen  Spean 
tilled  from  v  to  w  with  ice  of  a  uniform  elevation  of  1,500 
feet  above  the  sea,  the  ice  not  filling  the  upper  part  of  that 
glen.     The  ice  would  thrust  itself  for  some  distance  up  the   • 
lateral    valleys,   closing   all   their   mouths.     The   streams 
from  the  mountains  right  and  left  of  Glen   Gluoy  would 
pour  their  waters  into  that  glen,  forming  a  lake,  the  level 
of  which  would  be  determined  by  the  height  of  the  col,  at 
A,  1.170  feet  above  the  sea.     Over  this  col  the  water  would 
flow  into  Glen  Roy.     But  in  Glen  Roy  it  could   not  rise 
higher  than  1,150  feet,  the  height  of  the  col  at  B,  over 
which  it  would  flow  into  Glen  Spey. 

The  water  halting  at  these  'svels  for  a  sufficient  time, 
would  form  the  single  road  in  Glen  Gluoy  and  the  highest 
road  in  Glen  Roy.  This  state  of  things  would  continue 
as  long  as  the  ice  dam  was  sufficiently  high  to  dominate 
the  cols  at  A  and  B;  but  when  through  change  of  climate 
the  gradually  sinking  darn  reached,  in  succession,  the  levels 
of  these  cols,  the  water  would  then  begin  to  flow  over  the 
dam  instead  of  over  the  cols.  Let  us  suppose  the  wasting 
of  the  ice  to  continue  until  a  connection  was  established 
between  Glen  Roy  and  Glen  Glaster,  a  common  lake  would 
then  fill  both  these  glens,  the  level  of  which  would  be 
determined  by  that  of  the  col  C,  over  which  the  water 
would  pour  for  an  indefinite  period  into  Glen  Spean. 
During  this  period  the  second  Glen  Roy  road  and  the 
highest  road  of  Glen  Glaster  would  be  formed.  The  ice 
subsiding  still  further,  a  connection  would  eventually  be 


1?2  FRAGMENTS  OF  SCIENCE. 

established  between  Glen  Roy,  Glen  Glaster,  and  the 
upper  part  of  Glen  Spean.  A  common  lake  would  fill  all 
three  glens,  the  level  of  which  would  be  that  of  the  col  I), 
over  which  for  an  indefinite  period  the  lake  would  pour  its 
water.  During  this  period  the  lowest  Glen  Roy  road, 
which  is  common  also  to  Glen  Glaster  and  Glen  Spean, 
would  be  formed.  Finally,  on  the  disappearance  of  the 
ice  from  the  lower  part  of  Glen  Spean  the  waters  would 
flow  down  their  respective  valleys  as  they  do  to-day. 

Reviewing  our  work,  we  find  three  considerable  steps  to 
have  marked  the  solution  of  the  problem  of  the  Parallel 
Roads  of  Glen  Roy.  The  first  of  these  was  taken  by  Sir 
Thomas  Dick- Lander,  the  second  was  the  pregnant  concep- 
tion of  Agassiz  regarding  glacier  action,  and  the  third  was 
the  testing  and  verification  of  this  conception  by  the  very 
thorough  researches  of  Mr.  Jarnieson.  No  circumstance  or 
incident  connected  with  this  discourse  gives  me  greater 
pleasure  than  the  recognition  of  the  value  of  these 
researches.  They  are  marked  throughout  by  unflagging 
industry,  by  novelty  and  acuteness  of  observation,  and  by 
reasoning  power  of  a  high  and  varied  kind.  These  pages 
had  been  returned  "for  press  "when  I  learned  that  the 
relation  of  Ben  Nevis  and  his  colleagues  to  the  vapor-laden 
winds  of  the  Atlantic  had  not  escaped  Mr.  Jamieson.  To 
him  obviously  the  exploration  of  Lochaber,  and  the  develop- 
ment of  the  theory  of  the  Parallel  Roads,  has  been  a  labor 
of  love. 

Thus  ends  our  rapid  survey  of  this  brief  episode  in  the 
physical  history  of  the  Scottish  hills — brief,  that  is  to  say, 
in  comparison  with  the  immeasurable  lapses  of  time 
through  which,  to  produce  its  varied  structure  and  appear- 
ances, our  planet  must  have  passed.  In  the  survey  of 
such  a  field  two  things  are  specially  worthy  to  be  taken 
into  account — the  widening  of  the  intellectual  horizon  and 
the  reaction  of  expanding  knowledge  upon  the  intellectual 
organ  itself.  At  first,  as  in  the  case  of  ancient  glaciers, 
through  sheer  want  of  capacity,  the  mind  refuses  to  take 
in  revealed  facts.  But  by  degrees  the  steady  contemplation 
of  these  facts  so  strengthens  and  expands  the  intellectual 
powers,  that  where  truth  once  could  not  find  an  entrance 
it  eventually  finds  a  home.* 

*  The  formation ,  connection,  successive  subsidence,  and  final  dis- 
appearance of  the  glacial  lakes  of  Lochaber  were  illustrated  in  the 


THE  PARALLEL  ROADS  OF  GLEN  ROY.          173 


174  FRAGMENTS  OF  SCIENCE. 

A  map  of  the  district,  with  the  parallel  roads  shown,  is 
annexed.  

LITERATURE  OF  THE  SUBJECT. 

THOMAS  PENNANT. — A  tour  in  Scotland.     Vol.  iii.  1776,  p.  394. 
JOHN  MAcCuLLOCH. — On  the  Parallel  Roads  of  Glen  Roy.     Geol. 

Soc.  Trans,  vol.  iv.  1817,  p.  314. 
THOMAS    LAUDER    DICK    (afterward   SIR  THOMAS   DICK-LAUDER, 

Barrt.).— On  the  Parallel  Roads  of  Lochaber.     Edin.  Roy.   Soc. 

Trans.  1818,  vol.  ix.  p.  1. 
CHARLES  DARWIN. — Observations  on  tlie  Parallel  Roads  of  Glen  Roy, 

and  of  the  other  parts  of  Lochaber  in  Scotland,   with  an  attempt 

to  prove  that  they  are  of  marine  origin.     Phil.  Trans.  1839,  vol. 

cxxix.  p.  39. 
SIR    CHARLES    LYELL. — Elements    of    Geology.     Second     edition, 

1841. 
Louis   AGASSIZ. — The   Glacial   Theory   and   its    Recent   Progress — 

Parallel  Terraces.     Edin.  New  Phil.   Journal,   1842,  vol.   xxxiii. 

p.  236. 
DAVID  MILNE  (afterward  DAVID  MILNE-HOME).— On  the  Parallel 

Roads  of  Lochaber;   with  Remarks  on  the  Change  of  Relative 

Levels  of  Sea  and  Land  in  Scotland,  and  on  the  Detrital  Deposits 

in  that  Country.     Edin.  Roy.  Soc.  Trans.  1847,  vol.  xvi.  p.  395. 
ROBERT  CHAMBERS. — Ancient  Sea  Margins.     Edinburgh,  1848. 
H.  D.  ROGERS.— On  the   Parallel  Roads   of   Glen  Roy.     Royal  Inst. 

Proceedings,  1861,  vol.  iii.  p.  341. 
THOMAS  F.   JAMIESON.— On   the   Parallel   Roads  of  Glen   Roy,  and 

their  Place  in  the  History  of  the  Glacial  Period.     Quart.  Journal 

Geol.  Soc.  1863,  vol.  xix.  p.  235. 

SIR  CHARLES  LYELL.— Antiquity  of  Man.     1863,  p.  253. 
REV.  R.  B.  WATSON. — On  the  Marine  Origin  of  the   Parallel   Roads 

of  Glen  Roy.     Quart.  Journ.  Geol.  Soc.  1865,  vol.  xxii.  p.  9. 
SIR  JOHN  LUBBOCK. — On  the   Parallel  Roads   of  Glen   Roy.     Quart. 

Journ.  Geol.  Soc.  1867,  vol.  xxiv.  p.  83. 
CHARLES  BABBAGE. — Observations   on   the   Parallel   Roads  of   Glen 

Roy.     Quart.  Journ.  Geol.  Soc.  1868,  vol.  xxiv.  p.  273. 
JAMES  NICOL. — On  the   origin   of  the  Parallel   Roads  of  Glen  Roy. 

1869.     Geol.  Soc.  Journal,  vol.  xxv.  p.  282. 
JAMES  NICOL.— How  the  Parallel   Roads  of   Glen  Roy  were  formed. 

1872.     Geol.  Soc.  Journal,  vol.  xxviii.  p.  237. 
MAJOR-GENERAL  SIR  HENRY  JAMES,  R.  E.— Notes  on  the  Parallel 

Roads  of  Lochaber.     4to.     1874. 

discourse  here  reported  by  the  model  just  described,  constructed 
under  the  supervision  of  my  assistant,  Mr.  John  Cottrell.  Glen 
Gluoy  with  its  lake  and  road  and  the  cataract  over  its  col;  Glen  Roy 
and  its  three  roads  with  their  respective  cataracts  at  the  head  of  Glen 
Spey,  Glen  Glaster,  and  Glen  Spean,  were  all  represented.  The 
successive  shiftings  of  the  barriers,  which  were  formed  of  plate  glass, 
brought  each  successive  lake  and  its  corresponding  road  into  view, 
while  the  entire  removal  of  the  barriers  caused  the  streams  to  flow 
down  the  glens  of  the  inod.elas  they  flow  down  the  real  glens  of  to- 
day. 


ALPINE  SCULPTURE.  175 

CHAPTER  IX. 

ALPINE   SCULPTURE. 

1864. 

To  ACCOUNT  for  the  conformation  of  the  Alps,  two 
hypotheses  have  been  advanced,  which  may  be  respectively 
named  the  hypothesis  of  fracture  and  the  hypothesis  of 
erosion.  The  former  assumes  that  the  forces  by  which  the 
mountains  were  elevated  produced  fissures  in  the  earth's 
crust,  and  that  the  valleys  of  the  Alps  are  the  tracks  of 
these  fissures;  while  the  hitter  maintains  that  the  valleys 
have  been  cut  out  by  the  action  of  ice  and  water,  the 
mountains  themselves  being  the  residual  forms  of  this 
grand  sculpture.  I  had  heard  the  Via  Mala  cited  as  a 
conspicuous  illustration  of  the  fissure  theory — the  pro- 
found chasm  thus  named,  and  through  which  the  Hinter- 
Rhein  now  flows,  could,  it  was  alleged,  be  nothing  else 
than  a  crack  in  the  earth's  crust.  To  the  Via  Mala  I 
therefore  went  in  1804  to  instruct  myself  upon  the  point 
in  question. 

The  gorge  commences  about  a  quarter  of  an  hour  above 
Tusis;  and,  on  entering  it,  the  first  impression  certainly  is 
that  it  must  be  a  fissure.  This  conclusion  in  my  case  was 
modified  as  I  advanced.  Some  distance  up  the  gorge  I 
found  upon  the  slopes  to  my  right  quantities  of  rolled 
stones,  evidently  rounded  by  water-action.  Still  further 
up,  and  just  before  reaching  the  first  bridge  which  spans 
the  chasm,  I  found  more  rolled  stones,  associated  with 
sand  and  gravel.  Through  this  mass  of  detritus,  fortu- 
nately, a  vertical  cutting  had  been  made,  which  exhibited  a 
section  showing  perfect  stratification.  There  was  no 
agency  in  the  place  to  roll  these  stones,  and  to  deposic 
these  alternating  layers  of  sand  and  pebbles,  but  the  river 
which  now  rushes  some  hundreds  of  feet  below  them.  At 
one  period  of  the  Via  Mala's  history  the  river  must  have 
run  at  this  high  level.  Other  evidences  of  water-action 
soon  revealed  themselves.  From  the  parapet  of  the  first 
bridge  I  could  see  the  solid  rock  200  feet  above  the  bed  of 
the  river  scooped  and  eroded. 

It  is  stated  in  the  guide-books  that  the  river,  which  usu- 
ally runs  along  the  bottom  of  the  gorge,  has  been  known 
Almost  to  fill  it  during  violent  thunder-storms;  and  it  may 


176  FBA&MSNTS  OF  SCIENCE. 

be  urged  that  the  marks  of  erosion  which  the  sides  of  the 
chasm  exhibit  are  due  to  those  occasional  floods.  In  reply 
to  this,  it  may  be  stated  that  even  the  existence  of  such 
floods  is  not  well  authenticated,  and  that  if  the  supposition 
were  true,  it  would  be  an  additional  argument  in  favor  of 
the  cutting  power  of  the  river.  For  if  floods  operating  at 
rare  intervals  could  thus  erode  the  rock,  the  same  agency, 
acting  without  ceasing  upon  the  river's  bed,  must  certainly 
be  competent  to  excavate  it. 

I  proceeded  upward,  and  from  a  point  near  another 
bridge  (which  of  them  I  did  not  note)  had  a  fine  view  of  a 
portion  of  the  gorge.  The  river  here  runs  at  the  bottom 
of  a  cleft  of  profound  depth,  but  so  narrow  that  it  might 
be  leaped  across.  That  this  cleft  must  be  a  crack  is  the 
impression  first  produced;  but  a  brief  inspection  suffices  to 
prove  that  it  lias  been  cut  by  the  river.  From  top  to 
bottom  we  have  the  unmistakable  marks  of  erosion.  This 
cleft  was  best  seen  on  looking  downward  from  a  point 
near  the  bridge;  but  looking  upward  from  the  bridge 
itself,  the  evidence  of  aqueous  erosion  was  equally  con- 
vincing. 

The  character  of  the  erosion  depends  upon  the  rock  us 
well  as  upon  the  river.  The  action  of  water  upon  some 
rocks  is  almost  purely  mechanical;  they  are  simply  ground 
away  or  detached  in  sensible  masses.  Water,  however,  in 
passing  over  limestone,  charges  itself  with  carbonate  of 
lime  without  damage  to  its  transparency;  the  rock  is  dis- 
solved in  the  water;  and  the  gorges  cut  by  water  in  such 
rocks  often  resemble  those  cut  in  the  ice  of  glaciers  by  glacier 
streams.  To  the  solubility  of  limestone  is  probably  to  be  as- 
cribed the  fantastic  forms  which  peaks  of  this  rock  usually 
assume  and  also  the  grottos  and  caverns  which  interpenetrate 
limestone  formations.  A  rock  capable  of  being  thus  dissolved 
will  expose  a  smooth  surface  after  the  water  has  quitted  it; 
and  in  the  case  of  the  Via  Mala  it  is  the  polish  of  the  sur- 
faces and  the  curved  hollows  scooped  in  the  sides  of  the 
gorge,  which  assure  us  that  the  chasm  has  been  the  work 
of  the  river. 

About  four  miles  from  Tusis,  and  not  far  from  the  little 
village  of  Zillis,  the  Via  Mala  opens  into  a  plain  bounded 
by  high  terraces.  It  occurred  to  me  the  moment  I  saw  it 
that  the  plain  had  been  the  bed  of  an  ancient  lake;  and  a 
farmer,  who  was  my  temporary  companion,  immediately 


A  IP  INK  SCULPTURE.  iff 

informed  me  that  such  was  the  tradition  of  the  neighbor- 
hood. This  man  conversed  with  intelligence,  and  as  1  drew 
his  attention  to  the  rolled  stones,  which  rest  not  only  above 
the  river,  but  above  the  road,  and  inferred  that  the  river 
must  once  have  been  there  to  have  rolled  those  stones,  he 
saw  the  force  of  the  evidence  perfectly.  In  fact,  in-  former 
times,  and  subsequent  to  the  retreat  of  the  great  glaciers, 
a  rocky  barrier  crossed  the  valley  at  this  place,  damming 
the  river  which  came  from  the  mountains  higher  up.  A 
lake  was  thus  formed  which  poured  its  waters  over  the  bar- 
rier. Two  actions  were  here  at  work,  both  tending  to 
obliterate  the  lake — the  raising  of  its  bed  by  the  deposition 
of  detritus,  and  the  cutting  of  its  dam  by  the  river.  In 
process  of  time  the  cut  deepened  into  the  Via  Mala;  the 
lake  was  drained,  and  the  river  now  flows  in  a  definite 
channel  through  the  plain  which  its  waters  once  totally 
covered. 

From  Tusis  I  crossed  to  Tiefenkasten  by  the  Schien 
Pass,  and  thence  over  the  Julier  Pass  to  Pontresina.  There 
are  three  or  four  ancient  lake-beds  between  Tiefenkasten 
and  the  summit  of  the  Julier.  They  are  all  of  the  same 
type — a  more  or  less  broad  and  level  valley-bottom,  with  a 
barrier  in  front  through  which  the  river  has  cut  a  passage, 
the  drainage  of  the  lake  being  the  consequence.  These 
lakes  were  sometimes  dammed  by  barriers  of  rock,  sometimes 
by  the  moraines  of  ancient  glaciers. 

An  example  of  this  latter  kind  occurs  in  the  Rosegg  val- 
ley, about  twenty  minutes  below  the  end  of  the  Rosegg 
glacier,  and  about  an  hour  from  Pontresina.  The  valley 
here  is  crossed  by  a  pine-covered  moraine  of  the  noblest 
dimensions;  in  the  neighborhood  of  London  it  might  be 
called  a  mountain.  That  it  is  a  moraine,  the  inspection  of 
it  from  a  point  on  the  Surlei  slopes  above  it  will  convince 
any  person  possessing  an  educated  eye.  Where,  moreover, 
the  interior  of  the  mound  is  exposed,  it  exhibits  moraine- 
matter — detritus  pulverized  by  the  ice,  with  boulders  en- 
tangled in  it.  It  stretched  quite  across  the  valley,  and 
at  one  time  dammed  the  river  up.  But  now  the  barrier  is 
cut  through,  the  stream  having  about  one-fourth  of  the 
moraine  to  its  right,  and  the  remaining  three-fourths  to 
its  left.  Other  moraines  of  a  more  resisting  character  hold 
their  ground  as  barriers  to  the  present  day.  In  the  Val  di 
Campo,  for  example,  about  three-quarters  of  an  hour  from 


]  78  PR  A  GMENTS  OF  SCIENCE. 

Pisciadello,  there  is  a  moraine  composed  of  large  boulders, 
which  interrupt  the  course  of  a  river  and  compel  the  water 
to  fall  over  them  in  cascades.  They  have  in  great  part  re- 
sisted its  action  since  the  retreat  of  the  ancient  glacier 
which  formed  the  moraine.  Behind  the  moraine  is  a  lake- 
bed,  now  converted  into  a  level  meadow,  which  rests  on  a 
deep  layer  of  mold. 

At  Pontresina  a  very  fine  and  instructive  gorge  is  to  be 
seen.  The  river  from  the  Morteratsch  glacier  rushes 
through  a  deep  and  narrow  chasm  which  is  spanned  at  one 
place  by  a  stone  bridge.  The  rock  is  not  of  a  character  to 
preserve  smooth  polishing;  but  the  larger  features  of 
water-action  are  perfectly  evident  from  top  to  bottom. 
Those  features  are  in  part  visible  from  the  bridge,  but  still 
better  from  a  point  a  little  distance  from  the  bridge  in  the 
direction  of  the  upper  village  of  Pontresina.  The  hollow- 
ing out  of  the  rock  by  the  eddies  of  the  water  is  here  quite 
manifest.  A  few  minutes'  walk  upward  brings  us  to  the 
end  of  the  gorge;  and  behind  it  we  have  the  usual  indica- 
tions of  an  ancient  lake,  and  terraces  of  distinct  water 
origin.  From  this  position  indeed  the  genesis  of  the 
gorge  is  clearly  revealed.  After  the  retreat  of  the  ancient 
glacier,  a  transverse  ridge  of  comparatively  resisting 
material  crossed  the  valley  at  this  place.  Over  the  lowest 
part  of  this  ridge  the  river  flowed,  rushing  steeply  down  to 
join  at  the  bottom  of  the  slope  the  stream  which  issued 
from  the  Kosegg  glacier.  On  this  incline  the  water  be- 
came a  powerful  eroding  agent,  and  finally  cut  the  channel 
to  its  present  depth. 

Geological  writers  of  reputation  assume  at  this  place  the 
existence  of  a  fissure,  the  "  washing  out"  of  which  resulted 
in  the  formation  of  the  gorge.  Now  no  examination  of 
the  bed  of  the  river  ever  proved  the  existence  of  this  fissure; 
and  it  is  certain  that  water,  particularly  when  charged 
with  solid  matter  in  suspension,  can  cut  a  channel  through 
unfissured  rock.  Cases  of  deep  cutting  can  be  pointed 
out  where  the  clean  bed  of  the  stream  is  exposed,  the  rock 
which  forms  the  floor  of  the  river  not  exhibiting  a  trace  of 
fissure.  An  example  of  this  kind  on  a  small  scale  occurs 
near  the  Bernina  Gasthaus,  about  two  hours  from  Pont- 
resina. A  little  way  below  the  junction  of  the  two 
streams  from  the  Bernina  Pass  and  the  Hen  thai  the  river 
flows  through  a  channel  cut  by  itself,  and  20  or  30  feet  in 


ALPINE  SCULPTURE.  179 

depth.  At  some  places  the  river-bed  is  covered  with 
rolled  stones;  at  other  places  it  is  bare,  but  shows  no  trace 
of  fissure.  The  abstract  power  of  water,  if  I  may  use  the 
term,  to  cut  through  rock  is  demonstrated  by  such 
instances.  But  if  water  be  competent  to  form  a  gorge 
without  the  aid  of  a  fissure,  why  assume  the  existence  of 
such  fissures  in  cases  like  that  at  Pontresina?  It  seems 
far  more  philosophical  to  accept  the  simple  and  impressive 
history  written  on  the  walls  of  those  gorges  by  the  agent 
which  produced  them. 

Numerous  cases  might  be  pointed  out,  varying  in 
magnitude,  but  all  identical  in  kind,  of  barriers  which 
crossed  valleys  and  formed  lakes  having  been  cut  through 
by  rivers,  narrow  gorges  being  the  consequence.  One  of 
the  most  famous  examples  of  this  kind  is  the  Finster- 
aarschlucht  in  the  valley  of  Hasli.  Here  the  ridge  called 
theKirchet  seems  split  across,  and  the  river .Aar  rushes 
through  the  fissure.  Behind  the  barrier  we  have  the 
meadows  and  pastures  of  Imhof  resting  on  the  sediment  of 
an  ancient  lake.  Were  this  an  isolated  case,  one  might 
with  an  apparent  show  of  reason  conclude  that  the  Fins- 
teruarschlucht  was  produced  by  an  earthquake,  as  some 
suppose  it  to  have  been;  but  when  we  find  it  to  be  a  single 
sample  of  actions  which  are  frequent  in  the  Alps — when 
probably  a  hundred  cases  of  the  same  kind,  though  dif- 
ferent in  magnitude,  can  be  pointed  out — it  seems  quite 
unphilosophical  to  assume  that  in  each  particular  case  an 
earthquake  was  at  hand  to  form  a  channel  for  the  river. 
As  in  the  case  of  the  barrier  at  Pontresina,  the  Kirchet, 
after  the  retreat  of  the  Aar  glacier,  dammed  the  waters 
flowing  from  it,  thus  forming  a  lake,  on  the  bed  of  which 
now  stands  the  village  of  Imhof.  Over  this  barrier  the 
Aar  tumbled  toward  Meyringen.  cutting,  as  the  centuries 
passed,  its  bed  ever  deeper,  until  finally  it  became  deep 
enough  to  drain  the  lake,  leaving  in  its  place  the  alluvial 
plain,  through  which  the  river  now  flows  in  a  definite 
channel. 

In  1866  I  subjected  the  Finsteraarschlucht  to  a  close 
examination.  The  earthquake  theory  already  adverted  to 
was  then  prevalent  regarding  it,  and  I  wished  to  see 
whether  any  evidences  existed  of  aqueous  erosion.  Near 
the  summit  of  the  Kirchet  is  a  signboard  inviting  the 
traveler  to  visit  the  Aarenschlucht,  a  narrow  lateral  gorge 


180  FRAGMENTS  OF  SCIENCE. 

which  runs  down  to  the  very  bottom  of  the  principal  one". 
The  aspect  of  this  smaller  chasm  f  rom  bottom  to  top  proves  to 
demonstration  that  water  had  in  former  ages  been  there  at 
work.  It  is  scooped,  rounded,  and  polished,  so  as  to  render 
palpable  to  the  most  careless  eye  that  it  is  a  gorge  of 
erosion.  But  it  was  regarding  the  sides  of  the  great  chasm 
that  instruction  was  needed,  and  from  its  edge  nothing 
to  satisfy  me  could  be  seen.  I  therefore  stripped  and 
waded  into  the  river  until  a  point  was  reached  which  com- 
manded an  excellent  view  of  both  sides  of  the  gorge.  The 
water  was  cutting  cold,  but  I  was  repaid.  Below  me  on 
the  left-hand  side  was  a  jutting  cliff  which  bore  the  thrust 
of  the  river  and  caused  the  Aar  to  swerve  from  its  direct 
course.  From  top  to  bottom  this  cliff  was  polished,  rounded 
und  scooped.  There  was  no  room  for  doubt.  The  river 
which  now  runs  so  deeply  down  had  once  been  above.  It 
has  been  the  delver  of  its  own  channel  through  the  barrier 
of  the  Kirchet. 

But  the  broad  view  taken  by  the  advocates  of  the  frac- 
ture theory  is,  that  the  valleys  themselves  follow  the  tracks 
of  primeval  fissures  produced  by  the  upheaval  of  the  land, 
the  cracks  across  the  barriers  referred  to  being  in  reality 
portions  of  the  great  cracks  which  formed  the  valleys. 
Such  an  argument,  however,  would  virtually  concede  the 
theory  of  erosion  as  applied  to  the  valleys  of  the  Alps. 
The  narrow  gorges,  often  not  more  than  twenty  or  thirty 
feet  across,  sometimes  even  narrower,  frequently  occur  at 
the  bottom  of  broad  valleys.  Such  fissures  might  enter 
into  the  list  of  accidents  which  gave  direction  to  the  real 
erosive  agents  which  scooped  the  valley  out;  but  the  forma- 
tion of  the  valley,  as  it  now  exists,  could  no  more  be 
ascribed  to  such  cracks  than  the  motion  of  the  railway 
train  could  be  ascribed  to  the  finger  of  the  engineer  which 
turns  on  the  steam. 

These  deep  gorges  occur,  I  believe,  for  the  most  part  in 
limestone  strata;  and  the  effects  which  the  merest  driblet 
of  water  can  produce  on  limestone  are  quite  astonishing. 
It  is  not  uncommon  to  meet  chasms  of  considerable  depth, 
produced  by  small  streams  the  beds  of  which  are  dry  fora 
large  portion  of  the  year.  Eight  and  left  of  the  larger 
gorges  such  secondary  chasms  are  often  found.  The  idea 
of  time  must,  I  think,  be  more  and  more  included  in  our 
reasonings  on  these  phenomena.  Happily,  the  marks 


ALPINK  SCULPTURE.  181 

which  the  rivers  have,  in  most  cases,  left  behind  them,  and 
which  refer,  geologically  considered,  to  actions  of  yesterday, 
give  us  ground  and  courage  to  conceive  what  may  be  ef- 
fected in  geologic  periods.  Thus  the  modern  portion  of  the 
Via  Mala  throws  light  upon  the  whole.  Near  Bergiin,  in 
the  valley  of  the  Albula,  there  is  also  a  little  Via  Mala, 
which  is  not  less  significant  than  the  great  one.  The  river 
flows  here  through  a  profound  limestone  gorge,  and  to  the 
very  edges  of  the  gorge  we  have  the  evidences  of  erosion. 
But  the  most  striking  illustration  of  water-action  upon 
limestone  rock  that  I  have  ever  seen  is  the  gorge  at  Pfaffers. 
Here  the  traveler  passes  along  the  side  of  the  chasm  mid- 
way between  top  and  bottom.  Whichever  way  he  looks, 
backward  or  forward,  upward  or  downward,  toward  the 
sky  or  toward  the  river,  he  meets  everywhere  the  irresist- 
ible and  impressive  evidence  that  this  wonderful  fissure  has 
been  sawn  through  the  mountain  by  the  waters  of  the 
Tamina. 

I  have  thus  far  confined  myself  to  the  consideration  of 
the  gorges  formed  by  the  cutting  through  of  the  rock-bar- 
riers which  frequently  cross  the  valleys  of  the  Alps;  as  far 
as  they  have  been  examined  by  me  they  are  the  work  of 
erosion.  But  the  larger  question  still  remains,  To  what 
action  are  we  to  ascribe  the  formation  of  the  valleys  them- 
selves? This  question  includes  that  of  the  formation  of 
the  mountain-ridges,  for  were  the  valleys  wholly  filled,  the 
ridges  would  disappear.  Possibly  no  answer  can  be  given 
to  this  question  which  is  not  beset  with  more  or  less  of 
difficulty.  Special  localities  might  be  found  which  would 
seem  to  contradict  every  solution  which  refers  the  con- 
formation of  the  Alps  to  the  operation  of  a  single  cause. 

Still  the  Alps  present  features  of  a  character  sufficiently 
definite  to  bring  the  question  of  their  origin  within  the 
sphere  of  close  reasoning.  That  they  were  in  whole  or 
in  part  once  beneath  the  sea  will  not  be  disputed;  for  they 
are  in  great  part  composed  of  sedimentary  rocks  which  re- 
quired a  sea  to  form  them.  Their  present  elevation  above 
the  sea  is  due  to  one  of  those  local  changes  in  the  shape  of 
the  earth  which  have  been  of  frequent  occurrence  through- 
out geologic  time,  in  some  cases  depressing  the  land,  and  in 
others  causing  the  sea-bottom  to  protrude  beyond  its  sur- 
face. Considering  the  inelastic  character  of  its  materials, 
the  protuberance  of  the  Alps  could  hardly  have  been  pushed 


182  FRAGMENTS  OF  SCIENCE. 

out  without  dislocation  and  fracture;  and  this  conclusion 
gains  in  probability  when  we  consider  the  foldings,  contor- 
tions, and  even  reversals  in  position  of  the  strata  in  many 
parts  of  the  Alps.  Such  changes  in  the  position  of  beds 
which  were  once  horizontal  could  not  have  been  effected 
without  dislocation.  Fissures  would  be  produced  by  these 
changes;  and  such  fissures,  the  advocates  of  the  fracture 
theory  contend,  mark  the  positions  of  the  valleys  of  the 
Alps. 

Imagination  is  necessary  to  the  man  of  science,  and  we 
could  not  reason  on  our  present  subject  without  the  power 
of  presenting  mentally  a  picture  of  the  earth's  crust  cracked 
and  fissured  by  the  forces  which  produced  its  upheaval. 
Imagination,  however,  must  be  strictly  checked  by  reason 
and  by  observation.  That  fractures  occurred  cannot,  I 
think,  be  doubted,  but  that  the  valleys  of  the  Alps 
are  thus  formed  is  a  conclusion  not  at  all  involved  in  the 
admission  of  dislocations.  I  never  met  with  a  precise 
statement  of  the  manner  in  which  the  advocates  of  the 
fissure  theory  suppose  the  forces  to  have  acted — whether 
they  assume  a  general  elevation  of  the  region,  or  a  local 
elevation  of  distinct  ridges;  or  whether  they  assume  local 
subsidences  after  a  general  elevation,  or  whether  they 
would  superpose  upon  the  general  upheaval  minor  and  local 
upheavals. 

In  the  absence  of  any  distinct  statement,  I  will  assume 
the  elevation  to  be  general — that  a  swelling  out  of  the 
earth's  crust  occurred  here,  sufficient  to  place  the  most 
prominent  portions  of  the  protuberance  three  miles  above 
the  sea-level.  To  fix  the  ideas,  let  us  consider  a  circular 
portion  of  the  crust,  say  one  hundred  miles  in  diameter, 
and  let  us  suppose,  in  the  first  instance,  the  circumference 
of  this  circle  to  remain  fixed,  and  that  the  elevation  was 
confined  to  the,space  within  it.  The  upheaval  would  throw 
the  crust  into  a  state  of  strain;  and,  if  it  were  inflexible, 
the  strain  must  bo  relieved  by  fracture.  Crevasses  would 
thus  intersect  the  crust.  Let  us  now  inquire  what  propor- 
tion the  area  of  these  open  fissures  is  likely  to  bear  to  the 
unfissured  crust.  An  approximate  answer  is  all  that  is  here 
required;  for  the  problem  is  of  such  a  character  as  to  render 
minute  precision  unnecessary. 

No  one,  I  think,  would  affirm  that  the  area  of  the 
fissures  would  be  one-hundredth  the  area  of  the  land,  For 


ALPINE  SCULPTURE.  183 

let  us  consider  the  strain  upon  a  single  line  drawn  over  the 
summit  of  the  protuberance  from  a  point  on  its  rim  to  a 
point  opposite.  Regarding  the  protuberance  as  a  spherical 
swelling,  the  length  of  the  arc  corresponding  to  a  chord  of 
100  miles  and  a  versed  sine  of  three  miles  is  100.24  miles; 
consequently  the  surface  to  reach  its  new  position  must 
stretch  0.24  of  a  mile,  or  be  broken.  A  fissure  or  a  num- 
ber of  cracks  with  this  total  width  would  relieve  the  strain; 
that  is  to  say,  the  sum  of  the  widths  of  all  the  cracks  over 
the  length  of  100  miles  would  be  420  yards.  If  instead  of 
comparing  the  width  of  the  fissures  with  the  length  of  the 
lines  of  tension,  we  compared  their  areas  with  the  area  of 
the  unfissured  laud,  we  should  of  course  find  the  proportion 
much  less.  These  considerations  will  help  the  imagina- 
tion to  realize  what  a  small  ratio  the  area  of  the  open  fis- 
sures must  bear  to  the  unfissured  crust.  They  enable  us 
to  say,  for  example,  that  to  assume  the  area  of  the  fissures 
to  be  one-tenth  of  the  area  of  the  laud  would  be  quite 
absurd,  while  that  the  area  of  the  fissures  could  be  one- 
half  or  more  than  one-half  that  of  the  land  would  be  in  a 
proportionate  degree  unthinkable.  If  we  suppose  the 
elevation  to  be  due  to  the  shrinking  or  subsidence  of  the 
land  all  round  our  assumed  circle,  we  arrive  equally  at  the 
conclusion  that  the  area  of  the  open  fissures  would  be 
altogether  insignificant  as  compared  with  that  of  the  un- 
fissured crust. 

To  those  who  have  seen  them  from  a  commanding  eleva- 
tion, it  is  needless  to  say  that  the  Alps  themselves  bear  no 
sort  of  resemblance  to  the  picture  which  this  theory  pre- 
sents to  us.  Instead  of  deep  cracks  with  approximately 
vertical  walls,  we  have  ridges  running  into  peaks,  and 
gradually  sloping  to  form  valleys.  Instead  of  a  fissured 
crust,  we  have  a  state  of  things  closely  resembling  the  sur- 
face of  the  ocean  when  agitated  by  a  storm.  The  valleys, 
instead  of  being  much  narrower  than  the  ridges,  occupy 
the  greater  space.  A  plaster  cast  of  the  Alps  turned  up- 
side down,  so  as  to  invert  the  elevations  and  depressions, 
would  exhibit  blunter  and  broader  mountains,  with 
narrower  valleys  between  them,  than  the  present  ones.  The 
valleys  that  exist  cannot,  I  think,  with  any  correctness  of 
language  be  called  fissures.  It  may  be  urged  that  they 
originated  in  fissures:  but  even  this  is  unproved,  and,  were 
it  proved,  the  fissures  would  still  play  the  subordinate  part 


184  FRAGMENTS  OF  8GIENVE. 

of  giving  direction  to  the  agents  which  are  to  be  regarded 
as  the  real  sculptors  of  the  Alps. 

The  fracture  theory,  then,  if  it  regards  the  elevation  of 
the  Alps  as  due  to  the  operation  of  a  force  acting  through- 
out the  entire  region,  is,  in  my  opinion,  utterly  incom- 
petent to  account  for  the  conformation  of  the  country.  If, 
on  the  other  hand,  we  are  compelled  to  resort  to  local 
disturbances,  the  manipulation  of  the  earth's  crust  neces- 
sary to  obtain  the  valleys  and  the  mountains  will,  I 
imagine,  bring  the  difficulties  of  the  theory  into  very 
strong  relief.  Indeed  an  examination  of  the  region  from 
many  of  the  more  accessible  eminences — from  the  Galen- 
stock,  the  Grauhaupt,  the  Pitz  Languard,  the  Monte 
Confinale — or,  better  still,  from  Mont  Blanc,  Monte  Rosa, 
the  Jungfrau,  the  Finsteraarhorn,  the  Weisshorn,  or 
the  Matterhorn,  where  local  peculiarities  are  toned  down, 
and  the  operations  of  the  powers  which  really  made  this 
region  what  it  is  are  alone  brought  into  prominence — 
must,  I  imagine,  convince  every  physical  geologist  of 
the  inability  of  any  fracture  theory  to  account  for  the  pres- 
ent conformation  of  the  Alps. 

A  correct  model  of  the  mountains,  with  an  unexag- 
gerated  vertical  scale,  produces  the  same  effect  upon  the 
mind  as  the  prospect  from  one  of  the  highest  peaks.  We 
are  apt  to  be  influenced  by  local  phenomena  which, 
though  insignificant  in  view  of  the  general  question  of 
Alpine  conformation,  are,  with  reference  to  our  customary 
standards,  vast  and  impressive.  In  a  true  model  those 
local  peculiarities  disappear;  for  on  the  scale  of  a  model 
they  are  too  small  to  be  visible;  while  the  essential  facts 
and  forms  are  presented  to  the  undistracted  attention. 

A  minute  analysis  of  the  phenomena  strengthens  the 
conviction  which  the  general  aspect  of  the  Alps  fixes  in  the 
mind.  We  find,  for  example,  numerous  valleys  which  the 
most  ardent  plutonist  would  not  think  of  ascribing  to  any 
other  agency  than  erosion.  That  such  is  their  genesis  and 
history  is  as  certain  as  that  erosion  produced  the  Chines  in 
the  Isle  of  Wight.  From  these  indubitable  cases  of  erosion 
— commencing,  if  necessary,  with  the  small  ravines  which 
rundown  the  flanks  of  the  ridges,  with  their  little  working 
navigators  at  their  bottoms — we  can  proceed,  by  almost  in- 
sensible gradations,  to  the  largest  valleys  of  the  Alps;  and 
it  would  perplex  the  plutonist  to  fix  upon  the  point  at 
which  fracture  begins  to  play  a  material  part, 


ALPINE  SCULPTURE.  185 

In  ascending  one  of  the  larger  valleys,  we  enter  it  where 
it  is  wide  and  where  the  eminences  are  gentle  on  either 
side.  The  flanking  mountains  become  higher  and  more 
abrupt  as  we  ascend,  and  at  length  we  reach  a  place  where 
the  depth  of  the  valley  is  a  maximum.  Continuing  our 
walk  upward,  we  find  ourselves  flanked  by  gentler  slopes, 
and  finally  emerge  from  the  valley  and  reach  the  summit 
of  an  open  col,  or  depression  in  the  chain  of  mountains. 
This  is  the  common  character  of  the  large  valleys.  Cross- 
ing the  col,  we  descend  along  the  opposite  slope  of  the 
chain,  and  through  the  same  series  of  appearances  in  the 
reverse  order.  If  the  valleys  on  both  sides  of  the  col  were 
produced  by  fissures,  what  prevents  the  fissure  from  pro- 
longing itself  across  the  col?  The  case  here  cited  is 
representative;  and  I  am  not  acquainted  with  a  single 
instance  in  the  Alps  where  the  chain  has  been  cracked  in 
the  manner  indicated.  The  cols  are  simply  depressions, 
in  many  of  which  the  unfissured  rock  can  be  traced  from 
side  to  side. 

The  typical  instance  just  sketched  follows  as  a  natural 
consequence  from  the  theory  of  erosion.  Before  either  ice 
or  water  can  exert  great  power  as  an  erosive  agent,  it  must 
collect  in  sufficient  mass.  On  the  higher  slopes  and 
plateaus — in  the  region  of  cols — the  power  is  not  fully 
developed;  but  lower  down  tributaries  unite,  erosion  is 
carried  on  with  increased  vigor,  and  the  excavation  gradu- 
ally reaches  a  maximum.  Lower  still  the  elevations 
diminish  and  the  slopes  become  more  gentle;  the  cutting 
power  gradually  relaxes,  until  finally  the  eroding  agent 
quits  the  mountains  altogether,  and  the  grand  effects 
which  it  produced  in  the  earlier  portions  of  its  course 
entirely  disappear. 

I  have  hitherto  confined  myself  to  the  consideration  of 
the  broad  question  of  the  erosion  theory  as  compared  with 
the  fracture  theory;  and  all  that  I  have  been  able  to  observe 
and  think  with  reference  to  the  subject  leads  me  to  adopt 
the  former.  Under  the  term  erosion  I  include  the  action 
of  water,  of  ice,  and  of  the  atmosphere,  including  frost 
and  rain.  Water  and  ice,  however,  are  the  principal 
agents,  and  which  of  these  two  has  produced  the  greatest 
effect  it  is  perhaps  impossible  to  say.  Two  years  ago  I 
wrote  a  brief  note  "  On  the  Conformation  of  the  Alps,"  * 

*  Phil.  Mag.  vol.  xxiv.  j>.  169. 


186  FRAGMENTS  OF  SCIENCE. 

in  which  I  ascribed  the  paramount  influence  to  glaciers. 
The  facts  on  which  that  opinion  was  founded  are,  I 
think,  unassailable;  but  whether  the  conclusion  then  an- 
nounced fairly  follows  from  the  facts  is,  I  confess,  an  open 
question. 

The  arguments  which  have  been  thus  far  urged  against 
the  conclusion  are  not  convincing.  Indeed,  the  idea  of 
glacier  erosion  appears  so  daring  to  some  minds  that  its 
boldness  alone  is  deemed  its  sufficient  refutation.  It  is, 
however,  to  be  remembered  that  a  precisely  similar  position 
was  taken  up  by  many  excellent  workers  when  the  question 
of  ancient-  glacier  extension  was  first  mooted.  The  idea 
was  considered  too  hardy  to  be  entertained;  and  the 
evidences  of  glacial  action  were  sought  to  be  explained 
by  reference  to  almost  any  process  rather  than  the  true 
one.  Let  those  who  so  wisely  took  the  side  of  "  bold- 
ness" in  that  discussion  beware  lest  they  place  themselves, 
with  reference  to  the  question  of  glacier  erosion,  in  the 
position  formerly  occupied  by  their  opponents. 

Looking  at  the  little  glaciers  of  the  present  day — mere 
pygmies  as  compared  to  the  giants  of  the  glacial  epoch — 
we  find  that  from  every  one  of  them  issues  a  river  more  or 
less  voluminous,  charged  with  the  matter  which  the  ice  has 
rubbed  from  the  rocks.  Where  the  rocks  are  soft,  the 
amount  of  this  finely  pulverized  matter  suspended  in  the 
water  is  very  great.  The  water,  for  example,  of  the 
river  which  flows  from  Santa  Catarina  to  Bormio  is  thick 
with  it.  The  Rhine  is  charged  with  this  matter,  and 
by  it  has  so  silted  up  the  Lake  of  Constance  as  to  abolish 
it  for  a  large  fraction  of  its  length.  The  Rhone  is 
charged  with  it,  and  tens  of  thousands  of  acres  of  culti- 
vable laud  are  formed  by  the  silt  above  the  Lake  of 
Geneva. 

In  the  case  of  every  glacier  we  have  two  agents  at  work 
— the  ice  exerting  a  crushing  force  on  every  point  of  its 
bed  which  bears  its  weight,  and  either  rasping  this  point 
into  powder  or  tearing  it  bodily  from  the  rock  to  which  it 
belongs;  while  the  water  which  everywhere  circulates  upon 
the  bed  of  the  glacier  continually  washes  the  detritus  away 
and  leaves  the  rock  clean  for  further  abrasion  Confining 
the  action  of  glaciers  to  the  simple  rubbing  away  of  the 
rocks,  and  allowing  them  sufficient  time  to  act,  it  is  not  a 
matter  of  opinion,  but  a  physical  certainty,  that  they  will 


ALPINE  SCULPTURE.  187 

scoop  out  valleys.  But  the  glacier  does  more  than  abrade. 
Rocks  are  not  homogeneous;  they  are  intersected  by  joints 
and  places  of  weakness,  which  divide  them  into  virtually 
detached  masses.  A  glacier  is  undoubtedly  competent  to 
root  such  masses  bodily  away.  Indeed  the  mere  a  priori 
consideration  of  the  subject  proves  the  competence  of  a 
glacier  to  deepen  its  bed.  Taking  the  case  of  a  glacier 
1,000  feet  deep  (and  some  of  the  older  ones  were  probably 
three  times  this  depth),  and  allowing  40  feet  of  ice  to  an 
atmosphere,  we  find  that  on  every  square  inch  of  its  bed 
such  a  glacier  presses  with  a  weight  of  375  Ibs.,  and  on 
every  square  yard  of  its  bed  with  a  weight  of  486,000  Ibs. 
With  a  vertical  pressure  of  this  amount  the  glacier 
is  urged  down  its  valley  by  the  pressure  from  behind. 
We  can  hardly,  I  think,  deny  to  such  a  tool  a  power  of 
excavation. 

The  retardation  of  a  glacier  by  its  bed  has  been  referred 
to  as  proving  its  impotence  as  an  erosive  agent:  but  this 
very  retardation  is  in  some  measure  an  expression  of  the 
magnitude  of  the  erosive  energy.  Either  the  bed  must 
give  way,  or  the  ice  must  slide  over  itself.  We  get  indeed 
some  idea  of  the  crushing  pressure  which  the  moving 
glacier  exercises  against  its  bed  from  the  fact  that  the 
resistance,  and  the  effort  to  overcome  it,  are  such  as  to 
make  the  upper  layers  of  a  glacier  move  bodily  over  the 
lower  ones — a  portion  only  of  the  total  motion  being  due 
to  the  progress  of  the  entire  mass  of  the  glacier  down  its 
valley. 

The  sudden  bend  in  the  valley  of  the  Rhone  at  Martigny 
has  also  been  regarded  as  conclusive  evidence  against  the 
theory  of  erosion.  "  Why,"  it  has  been  asked,  "  did  not 
the  glacier  of  the  Rhone  go  straight  forward  instead  of 
making  this  awkward  bend?"  But  if  the  valley  be  a 
crack,  why  did  the  crack  make  this  bend?  The  crack,  I 
submit,  had  at  least  as  much  reason  to  prolong  itself  in  a 
straight  line  as  the  glacier  had.  A  statement  of  Sir  John 
Herschel  with  reference  to  another  matter  is  perfectly 
applicable  here:  "A  crack  once  produced  has  a  tendency 
to  run — for  this  plain  reason,  that  at  its  momentary  limit, 
at  the  point  at  which  it  has  just  arrived,  the  divellent 
force  on  the  molecules  there  situated  is  counteracted  only 
by  half  of  the  cohesive  force  which  acted  when  there  was 
no  crack,  viz.,|the  cohesion  of  the  uncracked  portion  alone  " 


188  FRAGMENTS  OF  SCIENCE. 

("  Proc.  Roy.  Soc."  vol.  xii.  p.  678).  To  account,  then, 
for  the  bend,  the  adherent  of  the  fracture  theory  must 
assume  the  existence  of  some  accident  which  turned  the 
crack  at  right  angles  to  itself;  and  he  surely  will  permit  the 
adherent  of  the  erosion  theory  to  make  a  similar  assump- 
tion. 

The  influence  of  small  accidents  on  the  direction  of 
rivers  is  beautifully  illustrated  in  glacier  streams,  which 
are  made  to  cut  either  straight  or  sinuous  channels  by 
causes  apparently  of  the  most  trivial  character.  In  his 
interesting  paper  "On  the  Lakes  of  Switzerland,"  M. 
Studer  also  refers  to  the  bend  of  the  Rhine  at  Sargans  in 
proof  that  the  river  must  there  follow  a  pre-existing 
fissure.  I  made  a  special  expedition  to  the  place  in  1864; 
and  though  it  was  plain  that  M.  Studer  had  good  grounds 
for  the  selection  of  this  spot,  I  was  unable  to  arrive  at  his 
conclusion  as  to  the  necessity  of  a  fissure. 

Again,  in  the  interesting  volume  recently  published  by 
the  Swiss  Alpine  Club,  M.  Desor  informs  us  that  the 
Swiss  naturalists  who  met  last  year  at  Samaden  visited  the 
end  of  the  Morteratsch  glacier,  and  there  convinced  them- 
selves that  a  glacier  had  no  tendency  whatever  to  imbed 
itself  in  the  soil.  I  scarcely  think  that  the  question  of 
glacier  erosion,  as  applied  either  to  lakes  or  valleys,  is  to 
be  disposed  of  so  easily.  Let  me  record  here  my  experience 
of  the  Morteratsch  glacier.  I  took  with  me  in  1864  a 
theodolite  to  Pontresina,  and  while  there  had  to  congrat- 
ulate myself  on  the  aid  of  my  friend  Mr.  Hirst,  who  in 
1857  did  such  good  service  upon  the  Mer  de  Glace  and  its 
tributaries.  We  set  out  three  lines  across  the  Morteratsch 
glacier,  one  of  which  crossed  the  ice-stream  near  the  well- 
known  hut  of  the  painter  Georgei,  while  the  two  others 
were  staked  out,  the  one  above  the  hut  and  the  other  below 
it.  Calling  the  highest  line  A,  the  line  which  crossed  the 
glacier  at  the  hut  B,  and  the  lowest  line  C,  the  following 
are  the  mean  hourly  motions  of  the  three  lines,  deduced 
from  observations  which  extended  over  several  days.  On 
each  line  eleven  stakes  were  fixed,  which  are  designated,  by 
the  figures  1,  8, 3,  etc.  in  the  tables. 

Morteratsch  Glacier,  Line  A. 

No.  of  Stake.  Hourly  Motion, 

1 0.35  inch 

2 0.49    " 

8 0.58    " 


ALPINE  SCULPTURE.  189 

4 ...0.54  inch 

5 0.56 

6 0.54 

7 0.52 

8 0.49 

9 0.40 

10 0.29     " 

11 0.20     " 

As  in  all  other  measurements  of  this  kind,  the  retarding 
influence  of  the  sides  of  the  glacier  is  manifest:  the  center 
moves  with  the  greatest  velocity. 

Morteratsch  Glacier,  Line  B. 

No.  of  Stake.  Hourly  Motion. 

1...  ...0.05  inch 

2 0.14  " 

3 0.24  " 

4 0.32  " 

5 0.41  " 

6 0.44  " 

7 0.44  " 

8 0.45  " 

9 0.43  " 

10  0.44  " 

11 0.44  " 

The  first  stake  of  this  line  was  quite  close  to  the  edge  of 
the  glacier,  and  the  ice  was  thin  at  the  place,  hence  its  slow 
motion.  Crevasses  prevented  us  from  carrying  the  line 
sufficiently  far  across  to  render  the  retardation  of  the  fur- 
ther side  of  the  glacier  fully  evident. 

Morteratsch  Glacier,  Line  0. 

No.  of  Stake.  Hourly  Motion. 

1 ...  0. 05  inch. 

2 0.09     " 

3 0.18     " 

4 0.20     " 

5 0.25     " 

6 0.27     " 

7 0.27     " 

8 0.30     " 

9 0.21     " 

10 0.20     " 

11 0.16     " 

Comparing  the  three  lines  together,  it  will  be  observed 
that  the  velocity  diminishes  as  we  descend  the  glacier.  In 


190  FRAGMENTS  OF  SCIENCE. 

100  hours  the  maximum  motion  of  the  three  lines  respec- 
tively is  as  follows: 

Maximum  Motion  in  100  hours. 

Line  A 56  inches. 

"    B 45       " 

"    C 30      " 

This  deportment  explains  an  appearance  which  must 
strike  every  observer  who  looks  upon  the  Morteratsch  from 
the  Piz  Languard,  or  from  the  new  Bernina  road.  A 
medial  moraine  runs  along  the  glacier,  commencing  as  a 
narrow  streak,  but  toward  the  end  the  moraine  extends 
in  width,  until  finally  it  quite  covers  the  terminal  portion 
of  the  glacier.  The  cause  of  this  is  revealed  by  the  fore- 
going measurements,  which  prove  that  a  stone  on  the 
moraine  where  it  is  crossed  by  the  line  A  approaches  a  sec- 
ond stone  on  the  moraine  where  it  is  crossed  by  the  line  C 
with  a  velocity  of  twenty-six  inches  per  one  hundred  hours. 
The  moraine  is  in  a  state  of  longitudinal  compression.  Its 
materials  are  more  and  more  squeezed  together,  and  they 
must  consequently  move  laterally  and  render  the  moraine 
at  the  terminal  portion  of  the  glacier  wider  than  above. 

The  motion  of  the  Morteratsch  glacier,  then,  diminishes 
as  we  descend.  The  maximum  motion  of  the  third  line  is 
thirty  inches  in  one  hundred  hours,  or  seven  inches  a  day 
— a  very  slow  motion;  and  had  we  run  a  line  nearer  to  the 
end  of  the  glacier,  the  motion  would  have  been  slower 
still.  At  the  end  itself  it  is  nearly  insensible.*  Now  I 
submit  that  this  is  not  the  place  to  seek  for  the  scooping 
power  of  a  glacier.  The  opinion  appears  to  be  prevalent 
that  it  is  the  snout  of  a  glacier  that  must  act  the  part  of 
plowshare;  audit  is  certainly  an  erroneous  opinion.  The 
scooping  power  will  exert  itself  most  where  the  weight  and 
the  motion  are  greatest.  A  glacier's  snout  often  rests 
upon  matter  which  has  been  scooped  from  the  glacier's  bed 
higher  up.  I  therefore  do  not  think  that  the  inspection  of 
what  the  end  of  a  glacier  does  or  does  not  accomplish  can 
decide  this  question. 

*  The  snout  of  the  Aletsch  Glacier  has  a  diurnal  -motion  of  less 
than  two  inches,  while  a  mile  or  so  above  the  snout  the  velocity  is 
eighteen  inches.  The  spreading  out  of  the  moraine  is  here  very 
striking. 


ALPINE  SCULPTURE,  191 

The  snout  of  a  glacier  is  potent  to  remove  anything 
against  which  it  can  fairly  abut;  and  this  power,  notwith- 
standing the  slowness  of  the  motion,  manifests  itself  at  the 
end  of  the  Morteratsch  glacier.  A  hillock,  bearing  pine 
trees,  was  in  front  of  the  glacier  when  Mr.  Hirst  and 
myself  inspected  its  end;  and  this  hillock  is  being  bodily 
removed  by  the  thrust  of  the  ice.  Several  of  the  trees  are 
overturned;  and  in  a  few  years,  if  the  glacier  continues  its 
reputed  advance,  the  mound  will  certainly  be  plowed 
away. 

The  question  of  Alpine  conformation  stands,  I  think, 
thus:  We  have,  in  the  first  place,  great  valleys,  such  as 
those  of  the  Rhine  and  the  Rhone,  which  we  might  con- 
veniently call  valleys  of  the  first  order.  The  mountains 
which  flank  these  main  valleys  are  also  cut  by  lateral 
valleys  running  into  the  main  ones,  and  which  may  be 
called  valleys  of  the  second  order.  When  these  latter  are 
examined,  smaller  valleys  are  found  running  into  them, 
which  may  be  called  valleys  of  the  third  order.  Smaller 
ravines  and  depressions,  again,  join  the  latter,  which  may 
be  called  valleys  of  the  fourth  order,  and  soon  until  we 
reach  streaks  and  cuttings  so  minute  as  not  to  merit  the 
name  of  valleys  at  all.  At  the  bottom  of  every  valley  we 
have  a  stream,  diminishing  in  magnitude  as  the  order  of 
the  vallev  ascends,  carving  the  earth  and  carrying  its 
materials  to  lower  levels.  We  find  that  the  larger  valleys 
have  been  filled  for  untold  ages  by  glaciers  of  enormous 
dimensions,  always  moving,  grinding  down  and  tearing 
away  the  rocks  over  which  they  passed.  We  have,  more- 
over, on  the  plains  at  the  feet  of  the  mountains,  and  in 
enormous  quantities,  the  very  matter  derived  from  the 
sculpture  of  the  mountains  themselves. 

The  plains  of  Italy  and  Switzerland  are  cumbered  by  the 
debris  of  the  Alps.  The  lower,  wider,  and  more  level 
valleys  are  also  filled  to  unknown  depths  with  the  materials 
derived  from  the  higher  ones.  In  the  vast  quantities  of 
moraine-matter  which  cumber  many  even  of  the  higher 
valleys  we  have  also  suggestions  as  to  the  magnitude  of  the 
erosion  which  has  taken  place.  This  moraine-matter, 
moreover,  can  only  in  small  part  have  been  derived  from 
the  falling  of  rocks  upon  the  ancient  glacier;  it  is  in  great 
part  derived  from  the  grinding  and  the  plowing-out  of 
the  glacier  itself.  This  accounts  for  the  magnitude  of 


1 92  FRAGMENTS  OF  SCIENCE. 

many  of  the  ancient  moraines,  which  date  from  a  period 
when  almost  all  the  mountains  were  covered  with  ice  and 
snow,  and  when,  consequently,  the  quantity  of  moraine- 
matter  derived  from  the  naked  crests  cannot  have  been 
considerable. 

The  erosion  theory  ascribes  the  formation  of  Alpine 
Valleys  to  the  agencies  here  briefly  referred  to.  It  invokes 
nothing  but  true  causes.  Its  artificers  are  still  there, 
though,  it  may  be,  in  diminished  strength;  and  if  they  are 
granted  sufficient  time,  it  is  demonstrable  that  they  are 
competent  to  produce  the  effects  ascribed  to  them.  And 
what  does  the  fracture  theory  offer  in  comparison?  From 
no  possible  application  of  this  theory,  pure  and  simple, 
can  we  obtain  the  slopes  and  forms  of  the  mountains. 
Erosion  must  in  the  long  run  be  invoked,  and  its  power 
therefore  conceded.  The  fracture  theory  infers  from  the 
disturbances  of  the  Alps  the  existence  of  fissures:  and  this 
is  a  probable  inference.  But  that  they  were  of  a  magni- 
tude sufficient  to  produce  the  conformation  of  the  Alps, 
and  that  they  followed,  as  the  Alpine  valleys  do,  the  lines 
of  natural  drainage  of  the  country,  are  assumptions  which 
do  not  appear  to  me  to  be  justified  either  by  reason  or  by 
observation. 

There  is  a  grandeur  in  the  secular  integration  of  small 
effects  implied  by  the  theory  of  erosion  almost  superior  to 
that  involved  in  the  idea  of  a  cataclysm.  Think  of  the 
ages  which  must  have  been  consumed  in  the  execution 
of  this  colossal  sculpture.  The  question  may,  of  course,  be 
pushed  further.  Think  of  the  ages  which  the  molten 
earth  required  for  its  consolidation.  But  these  vaster 
epochs  lack  sublimity  through  our  inability  to  grasp  them. 
They  bewilder  us,  but  they  fail  to  make  a  solemn  impres- 
sion. The  genesis  of  the  mountains  comes  more  within 
the  scope  of  the  intellect,  and  the  majesty  of  the  operation 
is  enhanced  by  our  partial  ability  to  conceive  it.  In  the 
falling  of  a  rock  from  a  mountain-head,  in  the  shoot  of  an 
avalanche,  in  the  plunge  of  a  cataract,  we  often  see  more 
impressive  illustrations  of  the  power  of  gravity  than  in  the 
motions  of  the  stars.  When  the  intellect  has  to  intervene, 
and  calculation  is  necessary  to  the  building  up  of  the  con- 
ception, the  expansion  of  the  feelings  ceases  to  be  pro- 
portional to  the  magnitude  of  the  phenomena. 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      193 

I  will  here  record  a  few  other  measurements  executed  on 
the  Rosegg  glacier:  the  line  was  staked  out  across  the 
trunk  formed  by  the  junction  of  the  Rosegg  proper  with 
the  Tschierva  glacier,  a  short  distance  below  the  rocky 
promontory  called  Agaliogs. 

Rosegg  Glacier. 

No.  of  Stake.  Hourly  Motion. 

1 0.01  inch. 

2 0.05 

3 0.07 

4 0.10 

5 0.11 

6 0.13 

7 0.14 

8 0.18 

9 0.24 

10 0.23 

11 0.24 

This  is  an  extremely  slowly  moving  glacier;  the  maxi- 
mum motion  hardly  amounts  to  seven  inches  a  day. 
Crevasses  prevented  us  from  continuing  the  line  quite 
across  the  glacier. 


CHAPTER  X. 

RECENT  EXPERIMENTS  ON   FOG  SIGNALS.* 

THE  CARE  of  its  sailors  is  one  of  the  first  duties  of  a 
maritime  people,  and  one  of  the  sailor's  greatest  dangers 
is  his  proximity  to  the  coast  at  night.  Hence  the  idea  of 
warning  him  of  such  proximity  by  beacon-fires  placed 
sometimes  on  natural  eminences  and  sometimes  on  towers 
built  expressly  for  the  purpose.  Close  to  Dover  Castle,  for 
example,  stands  an  ancient  Pharos  of  this  description. 

As  our  marine  increased  greater  skill  was  invoked,  and 
lamps  reinforced  by  parabolic  reflectors  poured  their  light 
upon  the  sea.  Several  of  these  lamps  were  sometimes 
grouped  together  so  as  to  intensify  the  light,  which  at  a 
little  distance  appeared  as  if  it  emanated  from  a  single 
source.  This  "catoptric"  form  of  apparatus  is  still  to 
some  extent  employed  in  our  lighthouse-service,  but  for  a 
long  time  past  it  has  been  more  and  more  displaced  by  the 
great  lenses  devised  by  the  illustrious  Frenchman,  Fresnel. 

*  A  discourse  delivered  in  the  Royal  Institution,  March  22,  1878. 


194  FRAGMENTS  OF  SCIENCE. 

In  a  first-class  "  dioptric  "  apparatus  the  light  emanates 
from  a  lamp  with  several  concentric  wicks,  the  flame  of 
which,  being  kindled  by  a  very  active  draught,  attains  to 
great  intensity.  In  fixed  lights  the  lenses  refract  the  rays 
issuing  from  the  lamp  so  as  to  cause  them  to  form  a  lumi- 
nous sheet  which  grazes  the  sea-horizon.  In  revolving  lights 
the  lenses  gather  up  the  rays  into  distinct  beams,  resem- 
bling the  spokes  of  a  wheel,  which  sweep  over  the  sea  and 
strike  the  eye  of  the  mariner  in  succession. 

It  is  not  for  clear  weather  that  the  greatest  strength- 
ening of  the  light  is  intended,  for  here  it  is  not  needed. 
Nor  is  it  for  densely  foggy  weather,  for  here  it  is  in- 
effectual. But  it  is  for  the  intermediate  stages  of  hazy, 
snowy,  or  rainy  weather,  in  which  a  powerful  light  can 
assert  itself,  while  a  feeble  one  is  extinguished.  The 
usual  first-order  lamp  is  one  of  four  wicks,  but  Mr.  Doug- 
lass, the  able  and  indefatigable  engineer  of  the  Trinity 
House,  has  recently  raised  the  number  of  the  wicks  to  six, 
which  produce  a  very  noble  flame.  To  Mr.  Wighain,  of 
Dublin,  we  are  indebted  for  the  successful  application  of 
gas  to  lighthouse  illumination.  In  some  lighthouses  his 
power  varies  from  28  jets  to  108  jets,  while  in  the  light- 
house of  Galley  Head  three  burners  of  the  largest  size  can 
be  employed,  the  maximum  number  of  jets  being  324. 
These  larger  powers  are  invoked  only  in  case  of  fog,  the 
28-jet  burner  being  amply  sufficient  for  clear  weather. 
The  passage  from  the  small  burner  to  the  large,  and  from 
the  large  burner  to  the  small,  is  made  with  ease,  rapidity, 
and  certainty.  This  employment  of  gas  is  indigenous  to 
Ireland,  and  the  Board  of  Trade  has  exercised  a  wise 
liberality  in  allowing  every  facility  to  Mr.  Wigham  for  the 
development  of  his  invention. 

The  last  great  agent  employed  in  lighthouse  illumination 
is  electricity.  It  was  in  this  Institution,  beginning  in 
1831,  that  Faraday  proved  the  existence  and  illustrated 
the  laws  of  those  induced  currents  which  in  our  day  have 
received  such  astounding  development.  In  relation  to 
this  subject  Faraday's  words  have  a  prophetic  ring.  "  I 
have  rather,"  he  writes  in  1831,  "been  desirous  of  dis- 
covering new  facts  and  new  relations  dependent  on  mag- 
neto-electric induction  than  of  exalting  the  force  of  those 
already  obtained,  being  assured  that  the  latter  would  find 
their  full  development  hereafter."  The  labors  of  Holmes, 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      195 

of  the  Paris  Alliance  Company,  of  Wilde,  and  of  Gramme, 
constitute  a  brilliant  fulfillment  of  this  prediction. 

But,  as  regards  the  augmentation  of  power,  the  greatest 
step  hitherto  made  was  independently  taken  a  few  years 
ago  by  Dr.  Werner  Siemens  and  Sir  Charles  Wheatstone. 
Through  the  application  of  their  discovery  a  machine 
endowed  with  an  infinitesimal  charge  of  magnetism  may, 
by  a  process  of  accumulation  at  compound  interest,  be 
caused  so  to  enrich  itself  magnetically  as  to  cast  by  its 
performance  all  the  older  machines  into  the  shade.  The 
light  now  before  you  is  that  of  a  small  machine  placed 
downstairs,  and  worked  there  by  a  minute  steam-engine. 
It  is  a  light  of  about  1,000  candles;  and  for  it,  and  for  the 
steam-engine  that  works  it,  our  members  are  indebted  to 
the  liberality  of  Dr.  William  Siemens,  who  in  the  most 
generous  manner  has  presented  the  machine  to  this  Insti- 
tution. After  an  exhaustive  trial  at  the  South  Foreland, 
machines  on  the  principle  of  Siemens,  but  of  far  greater 
power  than  this  one,  have  been  recently  chosen  by  the 
Elder  Brethren  of  the  Trinity  House  for  the  two  light- 
houses at  the  Lizard  Point. 

Our  most  intense  lights,  including  the  six-wick  lamp, 
the  Wigham  gas-light,  and  the  electric  light,  being  in- 
tended to  aid  the  mariner  in  heavy  weather,  may  be 
regarded,  in  a  certain  sense,  as  fog-signals.  But  fog,  when 
thick,  is  intractable  to  light.  The  sun  cannot  penetrate 
it,  much  less  any  terrestrial  source  of  illumination.  Hence 
the  necessity  of  employing  sound-signals  in  dense  fogs. 
Bells,  gongs,  horns,  whistles,  guns,  and  syrens  have  been 
used  for  this  purpose;  but  it  is  mainly,  if  not  wholly,  with 
explosive  signals  that  we  have  now  to  deal.  The  gun  has 
been  employed  with  useful  effect  at  the  North  Stack,  near 
Holy  head,  on  the  Kish  Bank  near  Dublin,  at  Lundy 
Island,  and  at  other  points  on  our  coasts.  During  the 
long,  laborious,  and  I  venture  to  think  memorable  series  of 
observations  conducted  under  the  auspices  of  the  Elder 
Brethren  of  the  Trinity  House  at  the  South  Foreland  in 
]872  and  1873,  it  was  proved  that  ashortS-^-inch  howitzer, 
firing  3  Ibs.  of  powder,  yielded  a  louder  report  than  a  long 
18-pouuder  firing  the  same  charge.  Here  was  a  hint  to  be 
acted  on  by  the  Elder  Brethren.  The  effectiveness  of  the 
sound  depended  on  the  shape  of  the  gun,  and  as  it  could 
not  be  assumed  that  in  the  howitzer  we  had  hit  accident- 


196  FRAGMENTS  OF  SCIENCE. 

ally  upon  the  best  possible  shape,  arrangements  were  made 
with  the  War  Office  for  the  construction  of  a  gun  specially 
calculated  to  produce  the  loudest  sound  attainable  from 
the  combustion  of  3  Ibs.  of  powder.  To  prevent  the 
unnecessary  landward  waste  of  the  sound,  the  gun  was 
furnished  with  a  parabolic  muzzle,  intended  to  project 
the  sound  over  the  sea,  where  it  was  most  needed.  The 
construction  of  this  gun  was  based  on  a  searching  series 
of  experiments  executed  at  Woolwich  with  small  models, 
provided  with  muzzles  of  various  kinds.  A  drawing 
of  the  gun  is  annexed  (p.  197).  It  was  constructed 
on  the  principle  of  the  revolver,  its  various  chambers 
being  loaded  and  brought  in  rapid  succession  into  the 
firing  position.  The  performance  of  the  gun  proved  the 
correctness  of  the  principles  on  which  its  construction  was 
based. 

An  incidental  point  of  some  interest  was  decided  by  the 
earliest  Woolwich  experiments.  It  had  been  a  widely 
spread  opinion  among  artillerists,  that  a  bronze  gun  pro- 
duces a  specially  loud  report.  I  doubted  from  the  outset 
whether  this  would  help  us;  and  in  a  letter  dated  April 
22d,  1874,  I  ventured  to  express  myself  thus:  "  The 
report  of  a  gun,  as  affecting  an  observer  close  at  hand,  is 
made  up  of  two  factors — the  sound  due  to  the  shock  of  the 
air  by  the  violently  expanding  gas,  and  the  sound  derived 
from  the  vibrations  of  the  gun,  which,  to  some  extent, 
rings  like  a  bell.  This  latter,  I  apprehend,  will  disappear 
at  considerable  distances/'  The  result  of  subsequent  trial, 
as  reported  by  General  Campbell,  is,  "  that  the  sonorous 
qualities  of  bronze  are  greatly  superior  to  those  of  cast  iron 
at  short  distances,  but  that  the  advantage  lies  with  the 
baser  metal  at  long  ranges/'* 

Coincident  with  these  trials  of  guns  at  Woolwich,  gun- 
cotton  was  thought  of  as  a  probably  effective  sound-produ- 
cer. From  the  first,  indeed,  theoretic  considerations  caused 
me  to  fix  my  attention  persistently  on  this  substance;  for 
the  remarkable  experiments  of  Mr.  Abel,  where  by  its  ra- 
pidity of  combustion  and  violently  explosive  energy  are 

*  General  Campbell  assigns  a  true  cause  for  this  difference.  The 
ring  of  the  bronze  gun  represents  so  mucb  energy  withdrawn  from 
the  explosive  force  of  the  gunpowder.  Further  experiments  would, 
however,  be  needed  to  place  the  superiority  of  the  cast-iron  gun  at  a 
distance  beyond  question. 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      197 

demonstrated,  seemed  to  single  it  out  as  a  substance  emi- 
nently calculated  to  fulfill  the  conditions  necessary  to  the 
production  of  an  intense  wave  of  sound.  What  those  con- 
ditions are  we  shall  now  more  particularly  inquire,  calling 
to  our  aid  a  brief  but  very  remarkable  paper,  published  by 
Professor  Stokes  in  the  Philosophical  Magazine  for 
1868. 

The  explosive  force  of  gunpowder  is  known  to  depend  on 
the  sudden  conversion  of  a  solid  body  into  an  intensely 
heated  gas.  Now  the  work  which  the  artillerist  requires 
the  expanding  gas  to  perform  is  the  displacement  of  the 
projectile,  besides  which  it  has  to  displace  the  air  in  front 


FIG.  6. 

Breech-loading  Fog-signal  Gun,  with  Bell  Mouth,*  proposed  by 
Major  Maitland,  R.A.,  Assistant  Superintendent. 

of  the  projectile,  which  is  backed  by  the  whole  pressure  of 
the  atmosphere.  Such,  however,  is  not  the  work  that  we 
want  our  gunpowder  to  perform.  We  wish  to  transmute 
its  energy  not  into  the  mere  mechanical  translation  of 
either  shot  or  air,  but  into  vibratory  motion.  We  want 
pulses  to  be  formed  which  shall  propagate  themselves  to 
vast  distances  through  the  atmosphere,  and  this  requires 
a  certain  choice  and  management  of  the  explosive  ma- 
terial. 

*  The  carriage  of  this  gun  has  been  modified  in  construction  since 
this  drawing  was  made. 


198  FRAGMENTS  OF  SCIENCE. 

A  sound-wave  consists  essentially  of  two  parts — a  con- 
densation, and  a  rarefaction.  Now  air  is  a  very  mobile 
fluid,  and  if  the  shock  imparted  to  it  lack  due  promptness, 
the  wave  is  not  produced.  Consider  the  case  of  a  common 
clock  pendulum,  which  oscillates  to  and  fro,  and  which 
might  be  expected  to  generate  corresponding  pulses  in  the 
air.  When,  for  example,  the  bob  moves  to  the  right,  the 
air  to  the  right  of  it  might  be  supposed  to  be  condensed, 
while  a  partial  vacuum  might  be  supposed  to  follow  the 
bob.  As  a  matter  of  fact,  we  have  nothing  of  the  kind. 
The  air  particles  in  front  of  the  bob  retreat  so  rapidly,  and 
those  behind  it  close  so  rapidly  in,  that  no  sound -pulse  is 
formed.  The  mobility  of  hydrogen,  moreover,  being  far 
greater  than  that  of  air,  a  prompter  action  is  essential  to 
the  formation  of  sonorous  waves  in  hydrogen  than  in  air. 
It  is  to  this  rapid  power  of  readjustment,  this  refusal,  so 
to  speak,  to  allow  its  atoms  to  be  crowded  together  or  to  be 
drawn  apart,  that  Professor  Stokes,  with  admirable  pene- 
tration, refers  the  damping  power,  first  described  by  Sir 
John  Leslie,  of  hydrogen  upon  sound. 

A  tuning-fork  which  executes  256  complete  vibrations  in 
a  second,  if  struck  gently  on  a  pad  and  held  in  free  air, 
emits  a  scarcely  audible  note.  It  behaves  to  some  extent 
like  the  pendulum  bob  just  referred  to.  This  feebleness  is 
due  to  the  prompt  "reciprocating  flow"  of  the  air  between 
the  incipient  condensations  and  rarefactions,  whereby  the 
formation  of  sound-pulses  is  forestalled.  Stokes,  however, 
has  taught  us  that  this  flow  may  be  intercepted  by  placing 
the  edge  of  a  card  in  close  proximity  to  one  of  the  corners 
of  the  fork.  An  immediate  augmentation  of  the  sound  of 
the  fork  is  the  consequence. 

The  more  rapid  the  shock  imparted  to  the  air,  the 
greater  is  the  fractional  part  of  the  energy  of  the  shock 
converted  into  wave  motion.  And  as  different  kinds  of 
gunpowder  vary  considerably  in  their  rapidity  of  combus- 
tion, it  may  be  expected  that  they  will  also  vary  as  pro- 
ducers of  sound.  This  theoretic  inference  is  completely 
verified  by  experiment.  In  a  series  of  preliminary  trials 
conducted  at  Woolwich  on  the  4th  of  June,  1875,  the 
sound-producing  powers  of  four  different  kinds  of  powder 
were  determined.  In  the  order  of  the  size  of  their  grains  they 
bear  the  names  respectively  of  Fine-grain  (F.  G.),  Large- 
Grain  (L.  G.),  Rifle  Large-grain  (R.  L.  G.),  and  Pebble- 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      109 

powder  (P.)  (See  annexed  figures.)  The  charge  in  each 
case  amounted  to  4£lbs.;  four  24-lb.  howitzers  being 
employed  to  tire  the  respective  charges.  There  were 
eleven  observers,  all  of  whom,  without  a  single  dissentient, 
pronounced  the  sound  of  the  fine-grain  powder  loudest  of 
all.  In  the  opinion  of  seven  of  the  eleven  the  large-grain 
powder  came  next;  seven  also  of  the  eleven  placed  the 
rifle  large-grain  third  on  the  list;  while  they  were  again 
unanimous  in  pronouncing  the  pebble-powder  the  worst 
sound-producer.  These  differences  are  entirely  due  to 
differences  in  the  rapidity  of  combustion.  All  who  have 
witnessed  the  performance  of  the  80-ton  gun  must  have 


F.G.  L.G. 

been  surprised  at  the  mildness  of  its  thunder.  To  avoid 
the  strain  resulting  from  quick  combustion,  the  powder 
employed  is  composed  of  lumps  far  larger  than  those  of 
the  pebble-powder  above  referred  to.  In  the  long  tube  of 
the  gun  these  lumps  of  solid  matter  gradually  resolve  them- 
selves into  gas,  which  on  issuing  from  the  muzzle  imparts 
a  kind  of  push  to  the  air,  instead  of  the  sharp  shock  nec- 
essary to  form  the  condensation  of  an  intensely  sonorous 
wave. 

These  are  some  of  the  physical  reasons  why  gun-cotton 
might  be  regarded  as  a  promising  fog-signal.  Firing  it  as 
we  have  been  taught  to  do  by  Mr.  Abel,  its  explosion  is 
more  rapid  than  that  of  gunpowder.  In  its  case  the  air 
particles,  alert  as  they  are,  will  not,  it  might  be  presumed, 
be  able  to  slip  from  condensation  to  rarefaction  with  a  ra- 
pidity sufficient  to  forestall  the  formation  of  the  wave.  On 
a  priori  grounds  then,  we  are  entitled  to  infer  the  effective- 
ness of  gun-cotton,  while  in  a  great  number  of  comparative 
experiments,  stretching  from  1874  to  the  present  time, 
this  inference  has  been  verified  in  the  most  conclusive 


$00  FRAGMENTS  OF  SCIENCE. 

As  regards  explosive  material,  and  zealous  and  accom- 
plished help  in  the  use  of  it,  the  resources  of  Woolwich 
Arsenal  have  been  freely  placed  at  the  disposal  of  the  Elder 
Brethren.  General  Campbell,  General  Younghusband, 
Colonel  Eraser,  Colonel  Maitland,  and  other  officers,  have 
taken  an  active  personal  part  in  the  investigation,  and  in 
most  cases  have  incurred  the  labor  of  reducing  and  report- 
ing on  the  observations.  Guns  of  various  forms  and  sizes 
have  been  invoked  for  gunpowder,  while  gun-cotton  has 
been  fired  in  free  air  and  in  the  foci  of  parabolic  reflectors. 

On  the  22d  of  February,  1875,  a  number  of  small  guns, 
cast  specially  for  the  purpose — some  with  plain,  some  with 
conical,  and  some  with  parabolic  muzzles — firing  4  oz.  of 
fine  grain  powder,  were  pitted  against  4  oz.  of  gun-cotton 
detonated  both  in  the  open  and  in  the  focus  of  a  parabolic 
reflector.*  The  sound  produced  by  the  gun-cotton,  rein- 
forced by  the  reflector,  was  unanimously  pronounced  loud- 
est of  all.  With  equal  unanimity,  the  gun-cotton  detonated 
in  free  air  was  placed  second  in  intensity.  Though  the 
same  charge  was  used  throughout,  the  guns  differed  notably 
among  themselves,  but  none  of  them  came  up  to  the  gun- 
cotton,  either  with  or  without  the  reflector.  A  second 
series,  observed  from  a  different  distance  on  the  same  day, 
confirmed  to  the  letter  the  foregoing  result. 

As  a  practical  point,  however,  the  comparative  cost  of 
gun-cotton  and  gunpowder  has  to  be  taken  into  account, 
though  considerations  of  cost  ought  not  to  be  stretched  too  far 
in  cases  involving  the  safety  of  human  life.  In  the  earlier 
experiments,  where  quantities  of  equal  price  were  pitted 
against  each  other,  the  results  were  somewhat  fluctuating. 
Indeed,  the  perfect  manipulation  of  the  gun-cotton  re- 
quired some  preliminary  discipline — promptness,  certainty, 
and  effectiveness  of  firing,  augmenting  as  experience  in- 
creased. As  1  Ib.  of  gun-cotton  costs  as  much  as  3  Ibs.  of 
gunpowder,  these  quantities  were  compared  together  on  the 
22d  of  February.  The  guns  employed  to  discharge  the 
gunpowder  were  a  12-lb.  brass  howitzer,  a  24-lb.  cast- 
iron  howitzer,  and  the  long  18-pounder  employed  at 
the  South  Foreland.  The  result  was,  that  the  24-lb. 
howitzer,  firing  3  Ibs.  of  gunpowder,  had  a  slight  ad- 
vantage  over  1  Ib.  of  gun-cotton  detonated  in  the  open; 

*  For  charges  of  this  weight  the  reflector  is  of  moderate  size,  and 
may  be  employed  without  fear  of  fracture. 


ttECENT  EXPERIMENTS  Oft  FOG  SIGNALS.      £0 1 

while  the  12-lb.  howitzer  and  the  18-pounder  were  botfti 
beaten  by  the  gun-cotton.  On  the  2d  of  May,  on  the 
other  hand,  the  gun-cotton  is  reported  as  having  been 
beaten  by  all  the  guns. 

'  Meanwhile,  the  parabolic-muzzle  gun,  expressly  intended 
for  fog- signaling,  was    pushed  rapidly  forward,  and   on 


FIG.  8. 

Gun-cotton  Slab  (1|  Ib.)  Detonated  in  the  Focus  of  a  Cast-iron 
Reflector. 

March  22  and  23,  1876,  its  power  was  tested  at  Shoebury- 
ness.  Pitted  against  it  were  a  16-pounder,  a  5^-inch  how- 
itzer, 1£  Ib.  of  gun-cotton  detonated  in  the  focus  of  a 
reflector  (see  annexed  figure),  and  l£  Ib-  of  gun-cotton  de- 
tonated in  free  air.  On  this  occasion  nineteen  different 
series  of  experiments  were  made,  when  the  new  experimen- 
tal gun,  firing  a  3-lb.  charge,  demonstrated  its  superiority 
over  all  guns  previously  employed  to  fire  the  same  charge. 
As  regards  the  comparative  merits  of  the  gun-cotton  fired 
in  the  open,  and  the  gunpowder  fired  from  the  new  gun, 
the  mean  values  of  their  sound  were  the  same.  Fired  in 
the  focus  of  the  reflector,  the- gun-cotton  clearly  dominated 
over  all  the  other  sound-producers.* 

*  The  reflector  was  fractured  by  the  explosion,  but  it  did  good  serv- 
ice afterward. 


202  FRAGMENTS  OF  SCIENCE. 

•The  whole  of  the  observations  here  referred  to  were  em- 
braced by  an  angle  of  about  70  degrees,  of  which  50 
degrees  lay  on  the  one  side  and  20  degrees  on  the  other  side 
of  the  line  of  fire.  The  shots  were  heard  by  eleven  observers 
on  board  the  Galatea,  which  took  up  positions  varying 
from  2  miles  to  13^  miles  from  the  firing-point.  In  all 
these  observations  the  reinforcing  action  of  the  reflector, 
and  of  the  parabolic  muzzle  of  the  gun,  came  into  play. 
But  the  reinforcement  of  the  sound  in  one  direction 
implies  its  withdrawal  from  some  other  direction, 
and  accordingly  it  was  found  that  at  a  distance  of  5£ 
miles  from  the  firing-point,  and  on  a  line  including  nearly 
an  angle  of  90  degrees  with  the  line  of  fire,  the  gun-cotton 
in  the  open  beat  the  new  gun;  while  behind  the  station, 
at  distances  of  8£  miles  and  13-£  miles  respectively,  the  gun- 
cotton  in  the  open  beat  both  the  gun  and  the  gun-cotton 
in  the  reflector.  This  result  is  rendered  more  important 
by  the  fact  that  the  sound  reached  the  Mucking  Light,  a 
distance  of  13£  miles,  against  a  light  wind  nhich  was 
blowing  at  the  time. 

Most,  if  not  all,  of  our  ordinary  sound-producers  send 
forth  waves  which  are  not  of  uniform  intensity  through- 
out. A  trumpet  is  loudest  in  the  direction  of  its  axis. 
The  same  is  true  of  a  gun.  A  bell,  with  its  mouth  pointed 
upward  or  downward,  sends  forth  waves  which  are  far 
denser  in  the  horizontal  plane  passing  through  the  bell 
than  at  an  angular  distance  of  90  degrees  from  that  plane. 
The  oldest  bellhangers  must  have  been  aware  of  the  fact 
that  the  sides  of  the  bell,  and  not  its  mouth,  emitted  the 
strongest  sound,  their  practice  being  probably  determined 
by  this  knowledge.  Our  slabs  of  gun-cotton  also  emit 
waves  of  different  densities  in  different  parts.  It  has 
occurred  in  the  experiments  at  Shoeburyness  that  when 
the  broad  side  of  a  slab  was  turned  toward  the  suspending 
wire  of  a  second  slab  six  feet  distant,  the  wire  was  cut  by 
the  explosion,  while  when  the  edge  of  the  slab  was  turned 
to  the  wire  this  never  occurred.  To  the  circumstance  that 
the  broadsides  of  the  slabs  faced  the  sea  is  probably  to  be 
ascribed  the  remarkable  fact  observed  on  March  23d,  that 
in  two  directions,  not  far  removed  from  the  line  of  fire,  the 
gun-cotton  detonated  in  the  open  had  a  slight  advantage 
over  the  new  gun. 

Theoretic  considerations  rendered   it  probable  that  the 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      203 

shape  and  size  of  the  exploding  mass  would  affect  the  con- 
stitution of  the  wave  of  sound.  I  did  not  think  large  reo* 
tangular  slabs  the  most  favorable  shape,  and  accordingly 
proposed  cutting  a  large  slab  into  fragments  of  different 
sizes,  and  pitting  them  against  each  other.  The  dif- 
ferences between  the  sounds  were  by  no  means  so  great  as 
the  differences  in  the  quantities  of  explosive  material 
might  lead  one  to  expect.  The  mean  values  of  eighteen 
series  of  observations  made  on  board  the  Galatea, 
at  distances  varying  from  If  mile  to  4.8  miles,  were  as 
follows: 

Weights 4oz.        6  oz.        9  oz.        12  oz. 

Value  of  sound 3.12         3.34         4.0  4.03 

These  charges  were  cut  from  a  slab  of  dry  gun-cotton 
about  If  inch  thick:  they  were  squares  and  rectangles  of 
the  following  dimensions:  4  oz.,  2  inches  by  2  inches;  6 
oz.,  2  inches  by  3  inches;  9  oz.,  3  inches  by  3  inches;  12 
oz.,  2  inches  by  6  inches. 

The  numbers  under  the  respective  weights  express  the 
recorded  value  of  the  sounds.  They  must  be  simply  taken 
as  a  ready  means  of  expressing  the  approximate  relative 
intensity  of  the  sounds  as  estimated  by  the  ear.  When  we 
find  a  9-oz.  charge  marked  4,  and  a  12-oz.  charge  marked 
4.03,  the  two  sounds  may  be  regarded  as  practically  equal 
in  intensity,  thus  proving  that  an  addition  of  30  percent, 
in  the  larger  charges  produces  no  sensible  difference  in  the 
sound.  Were  the  sounds  estimated  by  some  physical 
means,  instead  of  by  the  ear,  the  values  of  the  sounds  at 
the  distances  recorded  would  not,  in  my  opinion,  show  a 
greater  advance  with  the  increase  of  material  than  that 
indicated  by  the  foregoing  numbers.  Subsequent  experi- 
ments rendered  still  more  certain  the  effectiveness,  as  well 
as  the  economy,  of  the  smaller  charges  of  gun-cotton. 

It  is  an  obvious  corollary  from  the  foregoing  experiments 
that  on  our  "  nesses"  and  promontories,  where  the  land  is 
clasped  on  both  sides  for  a  considerable  distance  by  the 
sea — where,  therefore,  the  sound  has  to  propagate  itself 
rearward  as  well  as  forward — the  use  of  the  parabolic  gun, 
or  of  the  parabolic  reflector,  might  be  a  disadvantage 
rather  than  an  advantage.  Here  gun-cotton,  exploded  in 
the  open,  forms  the  most  appropriate  source  of  sound. 
This  remark  is  especially  applicable  to  such  lightships  as 


204  FRAGMENTS  OF  8C1ENC& 

are  intended  to  spread  the  sound  all  around  them  as  from 
central  foci.  As  a  signal  in  rock  lighthouses,  where 
neither  syren,  steam-whistle,  nor  gun  could  be  mounted; 
and  as  a  handy  fleet-signal,  dispensing  with  the  lumber  of 
special  signal-guns,  the  gun-cotton  will  prove  invaluable. 
But  in  most  of  these  cases  we  have  the  drawback  that  local 
damage  may  be  done  by  the  explosion.  The  lantern  of  the 
rock  lighthouse  might  suffer  from  concussion  near  at  hand, 
and  though  mechanical  arrangements  might  be  devised, 
both  in  the  case  of  the  lighthouse  and  of  the  ship's  deck, 
to  place  the  firing-point  of  the  gun-cotton  at  a  safe  dis- 
tance, no  such  arrangement  could  compete,  as  regards 
simplicity  and  effectiveness,  with  the  expedient  of  a  gun- 
cotton  rocket.  Had  such  a  means  of  signaling  existed  at 
the  Bishop's  Rock  lighthouse,  the  ill-fated  Schiller 
might  have  been  warned  of  her  approach  to  danger  ten,  or 
it  may  be  twenty  miles  before  she  reached  the  rock  which 
wrecked  her.  Had  the  fleet  possessed  such  a  signal, 
instead  of  the  ubiquitous  but  ineffectual  whistle,  the 
Iron  Duke  and  Vanguard  need  never  have  came  into 
collison. 

It  was  the  necessity  of  providing  a  suitable  signal  for 
rock  lighthouses,  and  of  clearing  obstacles  which  cast  an 
acoustic  shadow,  that  suggested  the  idea  of  the  gun-cotton 
rocket  to  Sir  Richard  Oollinson,  deputy  master  of  the 
Trinity  House.  His  idea  was  to  place  a  disk  or  short  cyl- 
inder of  gun-cotton  in  the  head  of  a  rocket,  the  ascensional 
force  of  which  should  be  employed  to  carry  the  disk  to  an 
elevation  of  1,000  feet  or  thereabouts,  where  by  the  ignition 
of  a  fuse  associated  with  a  detonator,  the  gun-cotton  should 
be  fired,  sending  its  sound  in  all  directions  vertically  and 
obliquely  down  upon  earth  and  sea.  The  first  attempt  to 
realize  this  idea  was  made  on  July  18,  1876,  at  the  firework 
manufactory  of  the  Messrs.  Brock,  at  Nunhead.  Eight 
rockets  were  then  fired,  four  being  charged  with  5  oz. 
and  four  with  7£  oz.  of  gun-cotton.  They  ascended  to  a 
great  height,  and  exploded  with  a  very  loud  report  in  the 
air.  On  July  27,  the  rockets  were  tried  at  Shoeburyness. 
The  most  noteworthy  result  on  this  occasion  was  the  hear- 
ing of  the  sounds  at  the  Mouse  lighthouse,  8-^  miles  E.  by 
S.,  and  at  the  Chapman  lighthouse,  8£  miles  W.  by  N.; 
that  is  to  say,  at  opposite  sides  of  the  firing  point.  It  is 
worthy  to  remark  that,  in  the  case  of  the  Chapman  light- 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      205 

house,  land  and  trees  intervened  between  the  firing-point 
and  the  place  of  observation.  "  This/'  as  General  Young- 
husband  justly  remarked  at  the  time,  "  may  prove  to  be  a 
valuable  consideration  if  it  should  be  found  necessary  to 
place  a  signal  station  in  a  position  whence  the  sea  could  not 
be  freely  observed."  Indeed,  the  clearing  of  such  obstacles 
was  one  of  the  objects  which  the  inventor  of  the  rocket  had 
in  view. 

With  reference  to  the  action  of  the  wind,  it  was  thought 
desirable  to  compare  the  range  of  explosions  produced  near 
the  surface  of  the  earth  with  others  produced  at  the  eleva- 
tion attainable  by  the  gun-cotton  rockets.  Wind  and 
weather,  however,  are  not  at  our  command;  and  hence  one 
of  the  objects  of  a  series  of  experiments  conducted  on 
December  13,  1876,  was  not  fulfilled.  It  is  worthy,  how- 
ever, of  note  that  on  this  day,  with  smooth  water  and  a  calm 
atmosphere,  the  rockets  were  distinctly  heard  at  a  distance 
of  11.2  miles  from  the  firing  point.  The  quantity  of  gun- 
cotton  employed  was  7£  oz.  On  Thursday,  March  8,  1877, 
these  comparative  experiments  of  firing  at  high  and  low 
elevations  were  pushed  still  further.  The  gun-cotton  near 
the  ground  consisted  of  |-lb.  disks,  suspended  from  a  hor- 
izontal iron  bar  about  4£  feet  above  the  ground.  The 
rockets  carried  the  same  quantity  of  gun-cotton  in  their 
heads,  and  the  height  to  which  they  attained,  as  determined 
by  a  theodolite,  was  from  800  to  '900  feet.  The  day  was 
cold,  with  occasional  squalls  of  snow  and  hail,  the  direc- 
tion of  the  sound  being  at  right  angles  to  that  of  the  wind. 
Five  series  of  observations  were  made  on  board  the 
Vestal,  at  distances  varying  from  3  to  6  miles.  The 
mean  value  of  the  explosions  in  the  air  exceeded  that  of 
the  explosions  near  the  ground  by  a  small  but  sensible 
quantity.  At  Windmill  Hill,  Gravesend,  however,  which 
was  nearly  to  leeward,  and  5£  miles  from  the  firing-point,  in 
nineteen  cases  out  of  twenty-four  the  disk  fired  near  the 
ground  was  loudest;  while  in  the  remaining  five  the 
rocket  had  the  advantage. 

Toward  the  close  of  the  day  the  atmosphere  became  very 
serene.  A  few  distant  cumuli  sailed  near  the  horizon,  but 
the  zenith  and  a  vast  angular  space  all  round  it  were  ab- 
solutely free  from  cloud.  From  the  deck  of  the  Galatea 
a  rocket  was  discharged,  which  reached  a  great  elevation, 
and  exploded  with  a  loud  report.  Following  this  soli4 


206  FRAGMENTS  OF  SCIENCE. 

nucleus  of  sound  was  a  continuous  train  of  echoes,  which 
retreated  to  a  continually  greater  distanc  e, dying  gradually 
off  into  silence  after  seven  seconds'  duration.  These  echoes 
were  of  the  same  character  as  those  so  frequently  noticed 
at  the  South  Foreland  in  1872-73,  and  called  by  me 
"  aerial  echoes." 

On  the  23d  of  March  the  experiments  were  resumed, 
the  most  noteworthy  results  of  that  day's  observations 
being  that  the  sounds  were  heard  at  Tillingham,  10  miles 
to  the  N.  E. ;  at  West  Mersea,  15|  miles  to  the  N.  E.  by 
E.;  at  Brightlingsea,  17^  miles  to  the  N.  E. ;  and  at 
Clacton  Wash,  20£  miles  to  the  N.  E.  by  £  E.  The  wind 
was  blowing  at  the  time  from  the  S.  E.  Some  of  these 
sounds  were  produced  by  rockets,  some  by  a  24-lb.  how- 
itzer, and  some  by  an  8-inch  Maroon. 

In  December,  1876,  Mr. Gardiner,  the  managing  director 
of  the  Cotton-powder  Company,  had  proposed  a  trial  of 
this  material  against  the  gun-cotton.  The  density  of  the 
cotton  he  urged  was  only  1.03,  while  that  of  the  powder 
was  1.70.  A  greater  quantity  of  explosive  material  being 
thus  compressed  into  the  same  volume,  Mr.  Gardiner 
thought  that  a  greater  sonorous  effect  must  be  produced 
by  the  powder.  At  the  instance  of  Mr.  Mackie,  who  had 
previously  gone  very  thoroughly  into  the  subject,  a  com- 
mittee of  the  Elder  Brethren  visited  the  cotton-powder 
manufactory,  on  the  banks  of  the  Swale,  near  Faversham, 
on  the  16th  of  June,  1877.  The  weights  of  cotton-powder 
employed  were  2  oz.,  8  oz.,  1  lb.,  and  2  Ibs.,  in  the  form 
of  rockets  and  of  signals  fired  a  few  feet  above  the  ground. 
The  experiments  throughout  were  arranged  and  conducted 
by  Mr.  Mackie.  Our  desire  on  this  occasion  was  to  get 
as  near  to  windward  as  possible,  but  the  Swale  and  other 
obstacles  limited  our  distance  to  1^  mile.  We  stood  here 
E.  S.  E.  from  the  firing-point  while  the  wind  blew  fresh 
from  the  N.  E. 

The  cotton-powder  yielded  a  very  effective  report.  The 
rockets  in  general  had  a  slight  advantage  over  the  same 
quantities  of  material  fired  near  the  ground.  Theloudness 
of  the  sound  was  by  no  means  proportional  to  the  quantity 
of  the  material  exploded,  8  oz.  yielding  very  nearly  as  loud 
a  report  as  1  lb.  The  "aerial  echoes,"  which  invariably 
followed  the  explosion  of  the  rockets,  were  loud  and  long- 
continued. 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.        207 


On  the  17th  of  October,  1877,  another  series  of  experi- 
ments with  howitzers  and  rockets  was  carried  out  at  Shoe- 
buryness.  The  charge  of  the  howitzer  was  3  Ibs.  of  L.  G. 
powder.  The  charges  of  the  rockets  were  12  oz.,  8  oz.,  4 
oz.,  and  2  oz.  of  gun-cotton  respectively.  The  gun  and 
the  four  rockets  constituted  a  series,  and  eight  series  were 
fired  during  the  afternoon  of  the  17th.  The  observations 
were  made  from  the  Vestal  and  the  Galatea,  positions 
being  successively  assumed  which  permitted  the  sound  to 
reach  the  observers  with  the  wind,  against  the  wind,  and 
across  the  wind.  The  distance  of  the  Galatea  varied 
from  3  to  7  miles,  that  of  the  Vestal,  which  was  more 
restricted  in  her  movements,  being  2  to  3  miles.  Briefly 
summed  up,  the  result  is  that  the  howitzer,  firing  a  3-lb. 
charge,  which  it  will  be  remembered  was  our  best  gun  at 
the  South  Foreland,  was  beaten  by  the  12-oz.  rocket,  by 
the  8-oz.  rocket,  and  by  the  4-oz.  rocket.  The  2-oz. 
rocket  alone  fell  behind  the  howitzer. 

It  is  worth  while  recording  the  distances  at  which  some 
of  the  sounds  were  heard  on  the  day  now  referred  to: 

24  out  of  40  sounds  heard. 


1.  Leigh  .     .     . 
2.  Girdler  Light- 
vessel      .     . 
3.  Reculvers 
4.  St.  Nicholas 
5.  Epple  Bay     . 
6.  Westgate 
7.  Kingsgate     . 

6$m 

12 

17* 
20 
22 
23 
25 

les  W.N.W.       24 

S.E.  by  E.      5 
S.E.  by  S.    18 
S.E.     .           3 
S.E.  by  E.    19 
S.E.  by  E.      9 
S.E.  by  E.      8 

The  day  was  cloudy,  with  occasional  showers  of  drizzling 
rain;  the  wind  about  N.W.  by  N.  all  day;  at  times  squally, 
rising  to  a  force  of  6  or  7  and  sometimes  dropping  to  a 
force  of  2  or  3.  The  station  at  Leigh  excepted,  all  these 
places  were  to  le  ward  of  Slioeburyness.  At  four  other 
stations  to  leeward,  varying  in  distance  from  15£  to 
24£  miles,  nothing  was  heard,  while  at  eleven  stations 
to  windward,  varying  from  8  to  26  miles,  the  sounds  were 
also  inaudible.  It  was  found,  indeed,  that  the  sounds 
proceeding  directly  against  the  wind  did  not  penetrate 
much  beyond  3  miles. 

On  the  following  day,  viz.,  October  18th,  we  pro- 
ceeded to  Dungeness  with  the  view  of  making  a  series  of 
strict  comparative  experiments  with  gun-cotton  and  cotton- 
powder.  Rockets  containing  8  oz.,  4  oz.,  and  2  oz.  of  gun- 
cotton  had  been  prepared  at  the  Royal  Arsenal;  while 


208  FRAGMENTS  OF  SCIENCE. 

others,  containing  similar  quantities  of  cotton-powder, 
had  been  supplied  by  the  Cotton-powder  Company  at 
Faversham.  With  these  were  compared  the  ordinary 
18-pounder  gun,  which  happened  to  be  mounted  at 
Dungeness,  firing  the  usual  charge  of  3  Ibs.  of  powder, 
and  a  syren. 

From  these  experiments  it  appeared  that  the  gun-cotton 
and  cotton-powder  were  practically  equal  as  producers  of 
sound. 

The  effectiveness  of  small  charges  was  illustrated  in  a 
very  striking  manner,  only  a  single  unit  separating  the 
numerical  value  of  the  8-oz.  rocket  from  that  of  the  2-oz. 
rocket.  The  former  was  recorded  as  6.9  and  the  latter  as 
5.9,  the  value  of  the  4-oz.  rocket  being  intermediate  be- 
tween them.  These  results  were  recorded  by  a  number  of 
very  practiced  observers  on  board  the  Galatea.  They  were 
completely  borne  out  by  the  observations  of  the  Coastguard 
who  marked  the  value  of  the  8-oz.  rocket  6.1,  and  that  of 
the  2-oz.  rocket  5.2.  The  18-pounder  gun  fell  far  behind 
all  the  rockets,  a  result,  possibly,  to  be  in  part  ascribed  to 
the  imperfection  of  the  powder.  The  performance  of  the 
syren  was,  on  the  whole,  less  satisfactory  than  that  of  the 
rocket.  The  instrument  was  worked,  not  by  steam  of  70 
Ibs.  pressure,  as  at  the  South  Foreland,  but  by  compressed 
air,  beginning  with  40  Ibs.  and  ending  with  30  Ibs. 
pressure.  The  trumpet  was  pointed  to  windward,  and 
in  the  axis  of  the  instrument  the  sound  was  about  as 
effective  as  that  of  the  8-oz.  rocket.  But  in  a  direction  at 
right  angles  to  the  axis,  and  still  more  in  the  rear  of  this 
direction,  the  syren  fell  very  sensibly  behind  even  the  2-oz. 
rocket. 

These  are  the  principal  comparative  trials  made  between 
the  gun-cotton  rocket  and  other  fog-signals;  but  they  are 
not  the  only  ones.  On  the  3d  of  August,  1877,  for 
example,  experiments  were  made  at  Lundy  Island  with  the 
following  results.  At  2  miles  distant  from  the  firing-point, 
with  land  intervening,  the  18-pounder,  firing  a  3-1  b. 
charge,  was  quite  unheard.  Both  the  4-oz.  rocket  and  the 
8-oz.  rocket,  however,  reached  an  elevation  which  com- 
manded the  acoustic  shadow,  and  yielded  loud  reports. 
When  both  were  in  view  the  rockets  were  still  superior  to 
the  gun.  On  the  6th  of  August,  at  St.  Ann's,  the  4-oz. 
and  8-oz.  rockets  proved  superior  to  the  syren.  On  the 


&ECENT  EXPERIMENTS  ON  FOQ  SIGNALS.      209 


Shambles  light-vessel,  when  a  pressure  of  13  Ibs.  was 
employed  to  sound  the  syren,  the  rockets  proved  greatly 
superior  to  that  instrument.  Proceeding  along  the  sea 
margin  at  Flamboro'  Head,  Mr.  Edwards  states  that  at  a 
distance  of  1£  mile,  with  the  18-pounder  previously  used 
as  a  fog-signal  hidden  behind  the  cliffs,  its  report  was  quite 
unheard,  while  the  4-oz.  rocket,  rising  to  an  elevation 
which  brought  it  clearly  into  view,  yielded  a  powerful 
sound  in  the  face  of  an  opposing  wind. 

On  the  evening  of  February  9,  1877,  a  remarkable 
series  of  experiments  were  made  by  Mr.  Prentice  at  Stow- 
market  with  the  gun-cotton  rocket.  From  the  report  with 
which  he  has  kindly  furnished  me  I  extract  the  following 
particulars.  The  first  column  in  the  annexed  statement 
contains  the  name  of  the  place  of  observation,  the  second 
its  distance  from  the  firing-point,  and  the  third  the  result 
observed: 
Stoke  Hill,  Ipswich  . 

Melton 


10  miles  Rockets  clearly  seen  and  sounds 
distinctly  heard  53  seconds 
after  the  flash. 

Signals  distinctly  heard. 
Thought  at  first  that  sounds 
were  reverberated  from  the 


15 


Framlingham      ....  18 

Stratford.  St.  Andrews    .  19 

Tuddenhani.     St.  Martin  10 

Christ  Church  Park.     .     .  11 

Nettlestead  Hall  6 


Bildestone 
Nacton 


14 


Aldboro' 25 

Capel  Mills 11 

Lawford      ......    15 


Signals  very  distinctly  heard, 
both  in  the  open  air  and  in  a 
closed  room.  Wind  in  favor 
of  sound. 

Reports  loud;  startled  pheasants 
in  a  cover  close  by. 

Reports  very  loud;  rolled  away 
like  thunder. 

Report  arrived  a  little  more  than 
a  minute  after  flash. 

Distinct  in  every  part  of  obser- 
ver's house.  Very  loud  in  the 
open  air. 

Explosion  very  loud,  wind 
against  sound. 

Reports  quite  distinct — mis- 
taken by  inhabitants  for  claps 
of  thunder. 

Rockets  seen  through  a  very 
hazy  atmosphere;  a  rumbling 
detonation  heard. 

Reports  heard  within  and. with- 
out the  observer's  house. 
Wind  opposed  to  sound. 

Reports  distinct;  attributed  to 
distant  thunder. 


$10  FRAGMENTS  OF  SCIENCE!. 

In  the  great  majority  of  these  oases,  the  direction  of  the 
sound  enclosed  a  large  angle  with  the  direction  of  the  wind. 
In  some  cases,  indeed,  the  two  directions  were  at  right 
angles  to  each  other.  It  is  needless  to  dwell  for  a  moment 
on  the  advantage  of  possessing  a  signal  commanding  ranges 
such  as  these. 

The  explosion  of  substances  in  the  air,  after  having  been 
carried  to  a  considerable  elevation  by  rockets,  is  a  familiar 
performance.  In  1873,  moreover,  the  Board  of  Trade 
proposed  a  light-and-sound  rocket  as  a  signal  of  distress, 
which  proposal  was  subsequently  realized,  but  in  a  form 
too  elaborate  and  expensive  for  practical  use.  The  idea  of 
a  gun  cotton  rocket  fit  for  signaling  in  fogs  is,  I  believe, 
wholly  due  to  Sir  Eichard  Collinson,  the  deputy  master 
of  the  Trinity  House.  Thanks  to  the  skillful  aid  given  by 
the  authorities  of  Woolwich,  by  Mr.  Prentice,  and  Mr. 
Brock,  that  idea  is  now  an  accomplished  fact;  a  signal  of 
great  power,  hand! ness,  and  economy,  being  thus  placed 
at  the  service  of  our  mariners.  Not  only  may  the  rocket 
be  applied  in  association  with  lighthouses  and  lightships, 
but  in  the  navy  also  it  may  be  turned  to  important 
account.  Soon  after  the  loss" of  the  Vanguard  I  ventured 
to  urge  upon  an  eminent  naval  officer  the  desirability  of 
having  an  organized  code  of  fog-signals  for  the  fleet. 
He  shook  his  head  doubtingly,  and  referred  to  the 
difficulty  of  finding  room  for  signal  guns.  The  gun-cotton 
rocket  completely  surmounts  this  difficulty.  It  is  manip- 
ulated with  ease  and  rapidity,  while  its  discharges  may 
be  so  grouped  and  combined  as  to  give  a  most  important 
extension  to  the  voice  of  the  admiral  in  command.  It  is 
needless  to  add  that  at  any  point  upon  our  coast,  or  upon 
any  other  coast,  where  its  establishment  might  be  desir- 
able, a  fog-signal  station  might  be  extemporized  without 
difficulty. 

I  have  referred  more  than  once  to  the  train  of  echoes 
which  accompanied  the  explosion  of  gun-cotton  in  free 
air,  speaking  of  them  as  similar  in  all  respects  to  those 
which  were  described  for  the  first  time  in  my  Report  on 
Fog-signals,  addressed  to  the  Corporation  of  Trinity 
House  in  1874.*  To  these  echoes  I  attached  a  funda- 

*  See  also  "  Philosophical  Transactions  "  for  1874,  p.  183. 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.      21 1 

mental  significance.  There  was  no  visible  reflecting  sur- 
face from  which  they  could  come.  On.  some  days,  with 
hardly  a  cloud  in  the  air  and  hardly  a  ripple  on  the  sea, 
they  reached  a  magical  intensity.  As  far  as  the  sense  of 
hearing  could  judge,  they  came  from  the  body  of  the  air 
in  front  of  the  great  trumpet  which  produced  them.  The 
trumpet  blasts  were  five  seconds  in  duration,  but  long 
before  the  blast  had  ceased  the  echoes  struck  in,  adding 
their  strength  to  the  primitive  note  of  the  trumpet.  After 
the  blast  had  ended  the  echoes  continued,  retreating  fur- 
ther and  further  from  the  point  of  observation,  and  finally 
dying  away  at  great  distances.  The  echoes  were  perfectly 
continuous  as  long  as  the  sea  was  clear  of  ships,  "  tapering  " 
by  imperceptible  gradations  into  absolute  silence.  But 
when  a  ship  happened  to  throw  itself  athwart  the  course 
of  the  sound,  the  echo  from  the  broadside  of  the  vessel  was 
returned  as  a  shock  which  rudely  interrupted  the  contin- 
uity of  the  dying  atmospheric  music. 

These  echoes  have  been  ascribed  to  reflection  from  the 
crests  of  the  sea-waves.  But  this  hypothesis  is  negatived 
by  the  fact  that  the  echoes  were  produced  in  great  inten- 
sity and  duration  when  no  waves  existed — when  the  sea, 
in  fact,  was  of  glassy  smoothness.  It  has  been  also  shown 
that  the  direction  of  the  echoes  depended  not  on  that  of 
waves,  real  or  assumed,  but  on  the  direction  of  the  axis  of 
the  trumpet.  Causing  that  axis  to  traverse  an  arc  of  210 
degrees,  and  the  trumpet  to  sound  at  various  points  of  the 
arc,  the  echoes  were  always,  at  all  events  in  calm  weather, 
returned  from  that  portion  of  the  atmosphere  toward  which 
the  trumpet  was  directed.'  They  could  not,  under  the 
circumstances,  come  from  the  glassy  sea;  while  both  their 
variation  of  direction  and  their  perfectly  continuous  fall 
into  silence,  are  irreconcilable  with  the  notion  that  they 
came  from  fixed  objects  on  the  land.  They  came  from 
that  portion  of  the  atmosphere  into  which  the  trumpet 
poured  its  maximum  sound,  and  fell  in  intensity  as  the 
direct  sound  penetrated  to  greater  atmospheric  distances. 

The  day  on  which  our  latest  observations  were  made  was 
particularly  fine.  Before  reaching  Dungeness.  the  smooth- 
ness of  the  sea  and  the  serenity  of  the  air  caused  me  to 
test  the  echoing  power  of  the  atmosphere.  A  single  ship 
lay  about  half  a  mile  distant  between  us  and  the  land. 
The  result  of  the  proposed  experiment  was  clearly  foreseen. 


$12  FRAGMENTS  OF  SCIENCE. 

It  was  this.  The  rocket  being  sent  up,  it  exploded  at  a 
great  height;  the  echoes  retreated  in  their  usual  fashion, 
becoming  less  and  less  intense  as  the  distances  of  the 
invisible  surfaces  of  reflection  from  the  observers  increased. 
About  five  seconds  after  the  explosion,  a  single  loud  shock 
was  sent  back  to  us  from  the  side  of  the  vessel  lying  be- 
tween us  and  the  land.  Obliterated  for  a  moment  by  this 
more  intense  echo,  the  aerial  reverberation  continued  its 
retreat,  dying  away  into  silence  in  two  or  three  seconds 
afterward.* 

I  have  referred  to  the  firing  of  an  8-oz.  rocket  from  the 
deck  of  the  Galatea  on  March  8,  1877,  stating  the 
duration  of  its  echoes  to  be  seven  seconds.  Mr.  Prentice, 
who  was  present  at  the  time,  assured  me  that  in  his  ex- 
periments similar  echoes  had  been  frequently  heard  of 
more  than  twice  this  duration.  The  ranges  of  his 
sounds  alone  would  render  this  result  in  the  highest 
degree  probable. 

To  attempt  to  interpret  an  experiment  which  I  have  not 
had  an  opportunity  of  repeating,  is  an  operation  of  some 
risk;  and  it  is  not  without  a  consciousness  of  this  that  I 
refer  here  to  a  result  announced  by  Professor  Joseph 
Henry,  which  he  considers  adverse  to  the  notion  of  aerial 
echoes.  He  took  the  trouble  to  point  the  trumpet  of  a 
syren  toward  the  zenith,  and  found  that  when  the  syren 
was  sounded  no  echo  was  returned.  Now  the  reflecting 
surfaces  which  give  rise  to  these  echoes  are  for  the  most 
part  due  to  differences  of  temperature  between  sea  and  air. 
If,  through  any  Cause,  the  air  above  be  chilled,  we  have 
descending  streams — if  the  air  below  be  warmed,  we  have 
ascending  streams  as  the  initial  cause  of  atmospheric  floc- 
culence.  A  sound  proceeding  vertically  does  not  cross  the 
streams,  nor  impinge  upon  the  reflecting  surfaces,  as  does 
a  sound  proceeding  horizontally  across  them.  Aerial 
echoes,  therefore,  will  not  accompany  the  vertical  sound 
as  they  accompany  the  horizontal  one.  The  experiment, 
as  I  interpret  it,  is  not  opposed  to  the  theory  of  these 
echoes  which  I  have  ventured  to  enunciate.  But,  as  I  have 
indicated,  not  only  to  see  but  to  vary  such  an  experiment 
is  a  necessary  prelude  to  grasping  its  full  significance. 

*  The  echoes  of  the  gun  fired  on  shore  this  day  were  very  brief; 
those  of  the  12-oz.  gun-cotton  rocket  were  12"  and  those  of  the  8-oz. 
cotton-powder  rocket  11 '  in  duration. 


RECENT  EXPERIMENTS  ON  FOG  SIGNALS.     213 

In  a  paper  published  in  the  "  Philosophical  Transac- 
tions" for  1876,  Professor  Osborne  Reynolds  refers  to 
these  echoes  in  the  following  terms:  "  Without  attempt- 
ing to  explain  the  reverberations  and  echoes  which  have 
been  observed,  Twill  merely  call  attention  to  the  fact  that 
in  no  case  have  I  heard  any  attending  the  reports  of  the 
rockets,*  although  they  seem  to  have  been  invariable 
with  the  guns  and  pistols.  These  facts  suggest  that  the 
echoes  are  in  some  way  connected  with  the  direction  given 
to  the  sound.  They  are  caused  by  the  voice,  trumpets, 
and  the  syren,  all  of  which  give  direction  to  the  sound; 
but  I  am  not  aware  that  they  have  ever  been  observed  in 
the  case  of  a  sound  which  has  no  direction  of  greatest  in- 
tensity." The  reference  to  the  voice,  and  other  references 
in  his  paper,  cause  me  to  think  that,  in  speaking  of  echoes, 
Professor  Osborne  Reynolds  and  myself  are  dealing  with 
different  phenomena.  Be  that  as  it  may,  the  foregoing 
observations  render  it  perfectly  certain  that  the  condition 
as  to  direction  here  laid  down  is  not  necessary  to  the  pro- 
duction of  the  echoes. 

There  is  not  a  feature  connected  with  the  aerial  echoes 
which  cannot  be  brought  out  by  experiments  in  the  air  of 
the  laboratory.  I  have  recently  made  the  following  experi- 
ment: A  rectangle,  x  Y  (p.  214),  22  inches  by  12,  was 
crossed  by  twenty-three  brass  tubes  (half  the  number 
would  suffice  and  only  eleven  are  shown  in  the  figure), 
each  having  a  slit  along  it  from  which  gas  can  issue.  In 
this  way  twenty-three  low  flat  flames  were  obtained.  A 
sounding  reed  a  fixed  in  a  short  tube  was  placed  at  one 
end  of  the  rectangle,  and  a  "  sensitive  flame,"f  /  »t  some 
distance  beyond  the  other  end.  When  the  reed  sounded, 
the  flame  in  front  of  it  was  violently  agitated,  and  roared 
boisterously.  Turning  on  the  gas,  and  lighting  it  as  it 
issued  from  the  slits,  the  air  above  the  flames  became  so 
heterogeneous  that  the  sensitive  flame  was  instantly  stilled, 
rising  from  a  height  of  6  inches  to  a  height  of  18  inches. 
Here  we  had  the  acoustic  opacity  of  the  air  in  front  of  the 
South  Foreland  strikingly  imitated.  J  Turning  off  the  gas, 

*  These  carried  12  oz.  of  gunpowder,  which  has  been  found  by 
Colonel  Fraser  to  require  an  iron  case  to  produce  an  effective  ex- 
plosion. 

f  Fully  described  in  my  "  Lectures  on  Sound,"  3d  edition,  p.  227, 

\  "  Lectures  on  Sound,"  84  ed.,  p.  208. 


214  FRAGMENTS  OF  SCIENCE. 

and  removing  the  sensitive  flame  to/',  some  distance  be- 
hind the  reed,  it  burned  there  tranquilly,  though  the  reed 
was  sounding.  Again  lighting  the  gas  as  it  issued  from 
the  brass  tubes,  the  sound  reflected  from  tb.e  heterogeneous 


air  threw  the  sensitive  flame  into  violent  agitation.  Here 
we  had  imitated  the  aerial  echoes  heard  when  standing 
behind  the  syren-trumpet  at  the  South  Foreland.  The 
experiment  is  extremely  simple,  and  in  the  highest  degree 
impressive. 


The  explosive  rapidity  of  dynamite  marks  it  as  a  sub- 
stance specially  suitable  for  the  production  of  sound.  At 
the  suggestion  of  Professor  Dewar,  Mr.  McRoberts  has 
carried  out  a  series  of  experiments  on  dynamite,  with 
extremely  promising  results.  Immediately  after  the 
delivery  of  the  foregoing  lecture  I  was  informed  that  Mr. 
Brock  proposed  the  employment  of  dynamite  in  the 
Gollinsou  rocket. 


ON  THE  STUDY  OF  PHYSICS.  215 

CHAPTER  XL 

ON  THE  STUDY  OF    PHYSICS.* 

I  HOLD  in  my  hand  an  uncorrected  proof  of  the  syllabus 
of  tliis  course  of  lectures,  and  the  title  of  the  present  lec- 
ture is  there  stated  to  be  "  On.the  Importance  of  the  Study 
of  Physics  as  a  Means  of  Education."  The  corrected  proof, 
however,  contains  the  title:  "On  the  Importance  of  the 
Study  of  Physics  as  a  Branch  of  Education."  Small  as 
this  editorial  alteration  may  seem,  the  two  words  suggest 
two  radically  distinct  modes  of  viewing  the  subject  before 
us.  The  term  Education  is  sometimes  applied  to  a  single 
faculty  or  organ,  and  if  we  know  wherein  the  education  of 
a  single  faculty  consists,  this  will  help  us  to  clearer  notions 
regarding  the  education  of  the  sum  of  all  the  faculties,  or 
of  the  mind.  When,  for  example,  we  speak  of  the  educa- 
tion of  the  voice,  what  do  we  mean?  There  are  certain 
membranes  at  the  top  of  the  windpipe  which  throw  into 
vibration  the  air  forced  between  them  from  the  lungs,  thus 
producing  musical  sounds.  These  membranes  are,  to  some 
extent,  under  the  control  of  the  will,  and  it  is  found  that 
they  can  be  so  modified  by  exercise  as  to  produce  notes  of 
a  clearer  and  more  melodious  character.  This  exercise  we 
call  the  education  of  the  voice.  We  may  choose  for  our 
exercise  songs  new  or  old,  festive  or  solemn;  the  education 
of  the  voice  being  the  object  aimed  at,  the  songs  may  be 
regarded  as  the  means  by  which  this  education  is  accom- 
plished. I  think  this  expresses  the  state  of  the  case  more 
clearly  than  if  we  were  to  call  the  songs  a  branch  of  edu- 
cation. Regarding  also  the  education  of  the  human  mind 
as  the  improvement  and  delvoprnent  of  the  mental  faculties, 
I  shall  consider  the  study  of  Physics  as  a  means  toward  the 
attainment  of  this  end.  From  this  point  of  view,  I  degrade 
Physics  into  an  implement  of  culture,  and  this  is  my  de- 
liberate design. 

The  term  Physics,  as  made  use  of  in  the  present 
Lecture,  refers  to  that  portion  of  natural  science  which  lies 
midway  between  astronomy  and  chemistry.  The  former 
indeed,  is  Physics  applied  to  "  masses  of  enormous  weight," 

*  From  a  lecture  delivered  in  the  Royal  Institution  of  Great  Britain 
in  the  spring  of  1854. 


216  FRAGMENTS  OF  SCIENCE. 

while  the  latter  is  Physics  applied  to  atoms  and  molecules. 
The  subjects  of  Physics  proper  are  therefore  those  which 
lie  nearest  to  human  perception:  light  and  heat,  color, 
sound,  motion,  the  loadstone,  electrical  attractions  and 
repulsions,  thunder  and  lightning,  rain,  snow,  dew,  and  so 
forth.  Our  senses  stand  between  these  phenomena  and  the 
reasoning  mind.  We  observe  the  fact,  but  are  not  satisfied 
with  the  mere  act  of  observation:  the  fact  must  be 
accounted  for — fitted  into  its  position  in  the  line  of  cause 
and  effect.  Taking  our  facts  from  Nature  we  transfer 
them  to  the  domain  of  thought:  look  at  them,  compare 
them,  observe  their  mutual  relations  and  connections,  and 
bringing  them  ever  clearer  before  the  mental  eye,  finally 
alight  upon  the  cause  which  unites  them.  This  is  the  last 
act  of  the  mind,  in  this  centripetal  direction — in  its  prog- 
ress from  the  multiplicity  of  facts  to  the  central  cause  on 
which  they  depend.  But,  having  guessed  the  cause,  we 
are  not  yet  contented.  We  set  out  from  the  center  and 
travel  in  the  other  direction.  If  the  guess  be  true,  certain 
consequences  must  follow  from  it,  and  we  appeal  to  the 
law  and  testimony  of  experiment  whether  the  tiling  is  so. 
Thus  is  the  circuit  of  thought  completed — from  without 
inward,  from  multiplicity  to  unity,  and  from  within 
outward,  from  unity  to  multiplicity.  In  thus  traversing 
both  ways  the  line  between  cause  and  effect,  all  our  reason- 
ing powers  are  called  into  play.  The  mental  effort  involved 
in  these  processes  may  be  compared  to  those  exercises 
of  the  body  which  invoke  the  co-operation  of  every  muscle, 
and  thus  confer  upon  the  whole  frame  the  benefits  of 
healthy  action. 

The  first  experiment  a  child  makes  is  a  physical  experi- 
ment: the  suction-pump  is  but  an  imitation  of  the  first 
act  of  every  new-born  infant.  Nor  do  I  think  it  calcu- 
lated to  lessen  that  infant's  reverence,  or  to  make  him  a 
worse  citizen,  when  his  riper  experience  shows  him  that 
the  atmosphere  was  his  helper  in  extracting  the  first 
draught  from  his  mother's  breast.  The  child  grows,  but 
is  still  an  experimenter:  he  grasps  at  the  moon,  and  his 
failure  teaches  him  to  respect  distance.  At  length  his 
little  fingers  acquire  sufficient  mechanical  tact  to  lay  hold 
of  a  spoon.  He  thrusts  the  instrument  into  his  mouth, 
hurts  his  gums,  and  thus  learns  the  impenetrability  of 
matter.  He  lets  the  spoon  fall,  and  jumps  with  delight  to 


ON  THE  STUDY  OF  PHYSICS.  217 

hear  it  rattle  against  the  table.  The  experiment  made  by 
accident  is  repeated  with  intention,  and  thus  the  young 
student  receives  his  first  lessons  upon  sound  and  gravita- 
tion. There  are  pains  and  penalties,  however,  in  the 
path  of  the  enquirer:  lie  is  sure  to  go  wrong,  and  Nature 
is  just  as  sure  to  inform  him  of  the  fact.  He  falls  down 
stairs,  burns  his  fingers,  cuts  his  hand,  scalds  his  tongue, 
and  in  this  way  learns  the  conditions  of  his  physical  well 
being.  This  is  Nature's  way  of  proceeding,  and  it  is 
wonderful  what  progress  her  pupil  makes.  His  enjoy- 
ments for  a  time  are  physical,  and  the  confectioner's  shop 
occupies  the  foreground  of  human  happiness;  but  the 
blossoms  of  a  finer  life  are  already  beginning  to  unfold 
themselves,  and  the  relation  of  cause  and  effect  dawns 
upon  the  boy.  He  begin  to  see  that  the  present  condi- 
tion of  things  is  not  final,  but  depends  upon  one  that  has 
gone  before,  and  will  be  succeeded  by  another.  He  be- 
comes a  puzzle  to  himself;  and  to  satisfy  his  newly 
awakened  curiosity,  asks  all  manner  of  inconvenient 
questions.  The  needs  and  tendencies  of  human  nature 
express  themselves  through  these  early  yearnings  of  the 
child.  As  thought  ripens,  he  desires  to  know  the 
character  and  causes  of  the  phenomena  presented  to  his 
observation;  and  unless  this  desire  has  been  granted  for 
the  express  purpose  of  having  it  repressed,  unless  the 
attractions  of  natural  phenomena  be  like  the  blush  of  the 
forbidden  fruit,  conferred  merely  for  the  purpose  of 
exercising  our  self-denial  in  letting  them  alone;  we  may 
fairly  claim  for  the  study  of  Physics  the  recognition  that  it 
answers  to  an  impulse  implanted  by  nature  in  the  constitu- 
tion of  man. 

A  few  days  ago,  a  master  of  arts,  who  is  still  a  young 
man,  and  therefore  the  recipient  of  a  modern  education, 
stated  to  me  that  until  he  had  reached  the  age  of  twenty 
years  he  had  never  been  taught  anything  whatever  regard- 
ing natural  phenomena,  or  natural  law.  Twelve  years  of 
his  life  previously  had  been  spent  exclusively  among  the 
ancients.  The  case,  I  regret  to  say,  is  typical.  Now,  we 
cannot,  without  prejudice  to  humanity,  separate  the  pres- 
ent from  the  past.  The  nineteenth  century  strikes  its 
roots  into  the  centuries  gone  by>  and  draws  nutriment 
from  them.  The  world  cannot  afford  to  lose  the  record  of 
any  great  deed  or  utterance;  for  such  are  prolific  through 


218  FRAGMENTS  OF  SCIENCE. 

out  all  time.  We  cannot  yield  the  companionship  of  our 
loftier  brothers  of  antiquity — of  our  Socrates  and  Cato — 
whose  lives  provoke  us  to  sympathetic  greatness  across  the 
interval  of  two  thousand  years.  As  long  as  the  ancient 
languages  are  the  means  of  access  to  the  ancient  mind, 
they  must  ever  be  of  priceless  value  to  humanity;  but 
surely  these  avenues  might  be  kept  open  without  making 
such  sacrifices  as  that  above  referred  to,  universal.  We 
have  conquered  and  possessed  ouiselves  of  continents  of 
land,  concerning  which  antiquity  knew  nothing;  and  if 
new  continents  of  thought  reveal  themselves  to  the  explor- 
ing human  spirit,  shall  we  not  possess  them  also?  In 
these  latter  days,  the  study  of  Physics  has  given  us 
glimpses  of  the  methods  of  Nature  which  were  quite  hidden 
from  the  ancients,  and  we  should  be  false  to  the  trust 
committed  to  us,  if  we  were  to  sacrifice  the  hopes  and 
aspirations  of  the  present  out  of  deference  to  the  past. 

The  bias  of  my  own  education  probably  manifests  itself 
in  a  desire  I  always  feel  to  seize  upon  every  possible 
opportunity"  of  checking  my  assumptions  and  conclusions 
by  experience.  In  the  present  case,  it  is  true,  your  own 
consciousness  might  be  appealed  to  in  proof  of  the  tendency 
of  the  human  mind  to  inquire  into  the  phenomena  pre- 
sented to  it  by  the  senses;  but  I  trust  you  will  excuse 
me  if,  instead  of  doing  this,  I  take  advantage  of  the 
facts  which  have  fallen  in  my  way  through  life,  refer- 
ring to  your  judgment  to  decide  whether  such  facts  are 
truly  representative  and  general,  and  not  merely  individual 
and  local. 

At  an  agricultural  college  in  Hampshire,  with  which  I 
was  connected  for  some  time,  and  which  is  now  converted 
into  a  school  for  the  general  education  of  youth,  a  society 
was  formed  among  the  boys,  who  met  weekly  for  the  pur- 
pose of  reading  reports  and  papers  upon  various  subjects. 
The  society  had  its  president  and  treasurer;  and  abstracts 
of  its  proceedings  were  published  in  a  little  monthly 
periodical  issuing  from  the  school  press.  One  of  the  most 
remarkable  features  of  these  weekly  meetings  was,  that 
after  the  general  business  had  been  concluded,  each 
member  en  joyed  the  right  of  asking  questions  on  any  sub- 
ject on  which  he  desired  information.  The  questions 
were  either  written  out  previously  in  a  book,  or,  if  a  ques- 
tion, happened  to  suggest  itself  during  the  meeting,  it  was 


ON  THE  STUD  T  OF  PHYSICS.  2]  9 

written  upon  a  slip  of  paper  and  handed  in  to  the  secretary, 
who  afterward  read  all  the  questions  aloud.  A  number  of 
teachers  were  usually  present,  and  they  and  the  boys  made 
a  common  stock  of  their  wisdom  in  furnishing  replies. 
As  might  be  expected  from  an  assemblage  of  eighty  or 
ninety  boys,  varying  from  eighteen  to  eight  years  old, 
many  odd  questions  were  proposed.  To  the  mind  which 
loves  to  detect  in  the  tendencies  of  the  young  the  instincts 
of  humanity  generally,  such  questions  are  not  without  a 
certain  philosophic  interest,  and  I  have  therefore  thought 
it  not  derogatory  to  the  present  course  of  lectures  to  copy 
a  few  of  them,  and  to  introduce  them  here.  They  run  as 
follows: 

What  are  the  duties  of  the  astronomer  royal? 

What  is  frost? 

Why  are  thunder  and  lightning  more  frequent  in  summer 
than  in  winter? 

What  occasions  falling  stars? 

What  is  the  cause  of  the  sensation  called  "  pins  and 
needles  ?" 

What  is  the  cause  of  waterspouts? 

What  is  the  cause  of  hiccough? 

If  a  towel  be  wetted  with  water,  why  does  the  wet 
portion  become  darker  than  before? 

What  is  meant  by  Lancashire  witches? 

Does  the  dew  rise  or  fall? 

What  is  the  principle  of  the  hydraulic  press? 

Is  there  more  oxygen  in  the  air  in  summer  than  in 
winter? 

What  are  those  rings  which  we  see  round  the  gas  and 
sun? 

What  is  thunder? 

How  is  it  that  a  black  hat  can  be  moved  by  forming 
round  it  a  magnetic  circle,  while  a  white  hat  remains 
stationary? 

What  is  the  cause  of  perspiration? 

Is  it  true  that  men  were  once  monkeys? 

What  is  the  difference  between  the  soul  and  the  mind  ? 

Is  it  contrary  to  the  rules  of  vegetarianism  to  eat  eggs? 

In  looking  over  these  questions,  which  were  wholly  un- 
prompted, and  have  been  copied  almost  at  random  from 
the  book  alluded  to,  we  see  that  many  of  them  are  sug- 
gested directly  by  natural  objects,  and  are  not  such  as  had 


220  FRAGMENTS  OF  SCIENCE. 

an  interest  conferred  on  them  by  previous  culture.  Now 
the  fact  is  beyond  the  boy's  control,  and  so  certainly  is  the 
desire  to  know  its  cause.  The  sole  question  then  is, 
whether  this  desire  is  to  be  gratified  or  not.  Who  created 
the  fact?  Who  implanted  the  desire?  Certainly  not  man. 
Who  then  will  undertake  to  place  himself  between  the 
desire  and  its  fulfillment,  and  proclaim  a  divorce  between 
them?  Take,  for  example,  the  case  of  the  wetted  towel, 
which  at  first  sight  appears  to  be  one  of  the  most  unprom- 
ising questions  in  the  list.  Shall  we  tell  the  proposer  to 
repress  his  curiosity,  as  the  subject  is  improper  for  him  to 
know,  and  thus  interpose  our  wisdom  to  rescue  the  boy 
from  the  consequences  of  a  wish  which  acts  to  his  prej- 
udice? Or,  recognizing  the  propriety  of  the  question, 
how  shall  we  answer  it?  It  is  impossible  to  answer  it  with- 
out reference  to  the  laws  of  optics — without  making  the 
boy  to  some  extent  a  natural  philosopher.  You  may  say 
that  the  effect  is  due  to  the  reflection  of  light  at  the 
common  surface  of  two  media  of  different  refractive  in- 
dices. But  this  answer  presupposes  on  the  part  of  the  boy 
a  knowledge  of  what  reflection  and  refraction  are,  or  re- 
duces you  to  the  necessity  of  explaining  them. 

On  looking  more  closely  into  the  matter,  we  find  that 
our  wet  towel  belongs  to  a  class  of  phenomena  which  have 
long  excited  the  interest  of  philosophers.  The  towel  is 
white  for  the  same  reason  that  snow  is  white,  that  foam  is 
white,  that  pounded  granite  or  glass  is  white,  and  that  the 
salt  we  use  at  table  is  white.  On  quitting  one  medium  and 
entering  another,  a  portion  of  light  is  always  reflected,  but 
on  this  condition — the  media  must  possess  different  re- 
fractive indices.  Thus,  when  we  immerse  a  bit  of  glass 
in  water,  light  is  reflected  from  the  common  surface  of 
both,  and  it  is  this  light  which  enables  us  to  see  the  glass. 
But  when  a  transparent  solid  is  immersed  in  a  liquid  of 
the  same  refractive  index  as  itself,  it  immediately  disap- 
pears. I  remember  once  dropping  the  eyeball  of  an  ox 
into  water;  it  vanished  as  if  by  magic,  with  the  exception 
of  the  crystalline  lens,  and  the  surprise  was  so  great  as  to 
cause  a  bystander  to  suppose  that  the  vitreous  humor  had 
been  instantly  dissolved.  This,  however,  was  not  the  case, 
and  a  comparison  of  the  refractive  index  of  the  humor 
with  that  of  water  cleared  up  the  whole  matter.  The  in- 
dices were  identical,  and  hence  the  light  pursued  its  way 
through  both  as  if  they  formed  one  continuous  rna,ss, 


ON"  THE!  STUD  7  OF  PHYSICS.  221 

In  the  case  of  snow,  powdered  quartz,  or  salt,  we  have  a 
transparent  solid  mixed  with  air.  At  every  transition 
from  solid  to  air,  or  from  air  to  solid,  a  portion  of  light  is 
reflected,  and  this  takes  place  so  often  that  the  light  is 
wholly  intercepted.  Thus  from  the  mixture  of  two  trans- 
parent bodies  we  obtain  an  opaque  one.  Now  the  case  of 
the  towel  is  precisely  similar.  The  tissue  is  composed  of 
semi-transparent  vegetable  fibers,  with  the  interstices  be- 
tween them  filled  with  air;  repeated  reflection  takes  place 
at  the  limiting  surfaces  of  air  and  fiber,  and  hence  the 
towel  becomes  opaque  like  snow  or  salt.  But  if  we  fill  the 
interstices  with  water,  we  diminish  the  reflection;  a  portion 
of  the  light  is  transmitted,  and  the  darkness  of  the  towel  is 
due  to  its  increased  transparency.  Thus  the  deportment  of 
various  minerals,  such  as  hydrophane  and  tabasheer,  the 
transparency  of  tracing  paper  used  by  engineers,  and  many 
other  considerations  of  the  highest  scientific  interest,  are 
involved  in  the  simple  inquiry  of  this  unsuspecting  little 
boy. 

Again,  take  the  question  regarding  the  rising  or  falling 
of  the  dew — a  question  long  agitated,  and  finally  set  at  rest 
by  the  beautiful  researches  of  Wells.  I  do  not  think  that 
any  boy  of  average  intelligeiiee  will  be  satisfied  with  the 
simple  answer  that  the  dew  falls.  He  will  wish  to  learn 
how  you  know  that  it  falls,  and,  if  acquainted  with  the 
notions  of  the  middle  ages,  he  may  refer  to  the  opinion  of 
Father  Laurns,  that  a  goose  egg  filled  in  the  morning  with 
dew  and  exposed  to  the  sun,  will  rise  like  a  balloon — a 
swan's  egg  being  better  for  the  experiment  than  a  goose 
egg.  It  is  impossible  to  give  the  boy  a  clear  notion  of  the 
beautiful  phenomenon  to  which  his  question  refers,  with- 
out first  making  him  acquainted  with  the  radiation  and 
conduction  of  heat.  Take,  for  example,  a  blade  of  grass, 
from  which  one  of  these  orient  pearls  is  depending.  During 
the  day  the  grass,  and  the  earth  beneath  it,  possess  a 
certain  amount  of  warmth  imparted  by  the  sun;  during  a 
serene  night,  heat  is  radiated  from  the  surface  of  the  grass 
into  space,  and  to  supply  the  loss,  there  is  a  flow  of  heat 
from  the  earth  to  the  blade.  Thus  the  blade  loses  heat  by 
radiation,  and  gains  heat  by  conduction.  Now,  in  the 
case  before  us,  the  power  of  radiation  is  great,  whereas  the 
power  of  conduction  is  small;  the  consequence  is  that  the 
blade  loses  more  than  it  gains,  and  hence  becomes  more 


222  FRAGMENTS  OF  SClENCti. 

and  more  refrigerated.  The  light  vapor  floating  around 
the  surface  so  cooled  is  condensed  upon  it,  and  there 
accumulates  to  form  the  little  pearly  globe  which  we  call  a 
dewdrop. 

Thus  the  boy  finds  the  simple  and  homely  fact  which 
addressed  his  senses  to  be  the  outcome  and  flower  of  the 
deepest  laws.  The  fact  becomes,  in  a  measure,  sanctified 
as  an  object  of  thought,  and  invested  for  him  with  a  beauty 
for  evermore.  He  thus  learns  that  things  which,  at  first 
sight,  seem  to  stand  isolated  and  without  apparent  brother- 
hood in  Nature  are  organically  united,  and  finds  the 
detection  of  such  analogies  a  source  of  perpetual  delight. 
To  enlist  pleasure  on  the  side  of  intellectual  performance 
is  a  point  of  the  utmost  importance;  for  the  exercise  of  the 
mind,  like  that  of  the  body,  depends  for  its  value  upon  the 
spirit  in  which  it  is  accomplished.  Every  physician  knows 
that  something  more  than  mere  mechanical  motion  is  com- 
prehended under  the  idea  of  healthful  exercise — that, 
indeed,  being  most  healthful  which  makes  us  forget  all 
ulterior  ends  in  the  mere  enjoyment  of  it.  What,  for 
example,  could  be  substituted  for  the  action  of  the  play- 
ground, where  the  boy  plays  for  the  mere  love  of  playing, 
and  without  reference  to  physiological  laws;  while  kindly 
Nature  accomplishes  her  ends  unconsciously,  and  makes 
his  very  indifference  beneficial  to  him.  You  may  have 
more  systematic  motions,  you  may  devise  means  for  the 
more  perfect  traction  of  each  particular  muscle,  but 
you  cannot  create  the  joy  and  gladness  of  the  game,  and 
where  these  are  absent,  the  charm  and  the  health  of  the 
exercise  are  gone.  The  case  is  similar  with  the  education 
of  the  mind. 

The  study  of  Physics,  as  already  intimated,  consists  of 
two  processes,  which  are  complementary  to  each  other — 
the  tracing  of  facts  to  their  causes,  and  the  logical  advance 
from  the  cause  to  the  fact.  In  the  former  process,  called 
induction,  certain  moral  qualities  come  into  play.  The 
first  condition  of  success  is  patient  industry,  an  honest 
receptivity,  and  a  willingness  to  abandon  all  preconceived 
notions,  however  cherished,  if  they  be  found  to  contradict 
the  truth.  Believe  me,  a  self-renunciation  which  has 
something  lofty  in  it,  and  of  which  the  world  never  hears, 
is  often  enacted  in  the  private  experience  of  the  true  votary 
of  science.  And  if  a  man  be  not  capable  of  this  self-renun- 


ON-  THE  STVD  T  OF  PKY8ICS.  223 

ciation — this  loyal  surrender  of  himself  to  Nature  and  to 
fact,  lie  lacks,  in  my  opinion,  the  first  mark  of  a  true 
philosopher.  Thus  the  earnest  prosecutor  of  science,  who 
does  not  work  with  the  idea  of  producing  a  sensation  in 
the  world,  who  loves  the  truth  better  than  the  transitory 
blaze  of  to-day's  fame,  who  comes  to  his  task  with  a  single 
eye,  finds  in  that  task  an  indirect  means  of  the  highest 
moral  culture.  And  although  the  virtue  of  the  act  depends 
upon  its  privacy,  this  sacrifice  of  self,  this  upright  deter- 
mination to  accept  the  truth,  no  matter  how  it  may  present 
itself — even  at  the  hands  of  a  scientific  foe,  if  necessary — 
carries  with  it  its  own  reward.  When  prejudice  is  put  under 
foot  and  the  stains  of  personal  bias  have  been  washed  away 
— when  a  man  consents  to  lay  aside  his  vanity  and  to 
become  Nature's  organ — his  elevation  is  the  instant  conse- 
quence of  his  humility.  I  should  not  wonder  if  my  remarks 
provoked  a  smile,  for  they  seem  to  indicate  thac  I  regard 
the  man  of  science  as  a  heroic,  if  not  indeed  an  angelic, 
character;  and  cases  may  occur  to  you  which  indicate  the 
reverse.  You  may  point  to  the  quarrels  of  scientific  men, 
at  their  struggles  for  priority,  to  that  unpleasant  egotism 
which  screams  around  its  little  property  of  discovery  like  a 
scared  plover  about  its  young.  I  will  not  deny  all  this;  but 
let  it  be  set  down  to  its  proper  account,  to  the  weakness — 
or,  if  you  will — to  the  selfishness  of  Man,  but  not  to  the 
charge  of  Physical  Science. 

The  second  process  in  physical  investigation  is  deduction, 
or  the  advance  of  the  mind  from  fixed  principles  to  the 
conclusions  which  flow  from  them.  The  rules  of  logic  are 
the  formal  statement  of  this  process,  which,  however,  was 
practiced  by  every  healthy  mind  before  ever  such  rules 
were  written.  In  the  study  of  Physics,  induction  and  de- 
duction are  perpetually  wedded  to  each  other.  The  man 
observes,  strips  facts  of  their  peculiarities  of  form,  and 
tries  to  unite  them  by  their  essences;  having  effected  this, 
he  at  once  deduces,  and  thus  checks  his  induction.  Here 
the  grand  difference  between  the  methods  at  present  fol- 
lowed, and  those  of  the  ancients,  becomes  manifest.  They 
were  one-sided  in  these  matters:  they  omitted  the  process 
of  induction,  and  substituted  conjecture  for  observation. 
They  could  never,  therefore,  fulfill  the  mission  of  Man  to 
"  replenish  the  earth,  and  subdue  it."  The  subjugation  of 
Nature  is  only  to  be  accomplished  by  the  penetration,  of 


224  FRAGMENTS  OP  SCIENCE. 

her  secrets  and  the  patient  mastery  of  her  laws.  This  not 
only  enables  ns  to  protect  ourselves  from  the  hostile  action 
of  natural  forces,  but  makes  them  our  slaves.  By  the  study 
of  Physics  we  have  indeed  opened  to  us  treasuries  of  power 
of  which  antiquity  never  dreamed.  But  while  we  lord  it 
over  Matter,  we  have  thereby  become  better  acquainted 
with  the  laws  of  Mind;  for  to  the  mental  philosopher  the 
study  of  Physics  furnishes  a  screen  against  which  the  human 
spirit  projects  its  own  image,  and  thus  becomes  capable  of 
self-inspection. 

Thus,  then,  as  a  means  of  intellectual  culture,  the  study 
of  Physics  exercises  and  sharpens  observation :  it  brings  the 
most  exhaustive  logic  into  play:  it  compares,  abstracts, 
and  generalizes,  and  provides  a  mental  scenery  appropriate 
to  these  processes.  The  strictest  precision  of  thought  is 
everywhere  enforced,  and  prudence,  foresight,  and  sagac- 
ity are  demanded.  By  its  appeals  to  experiment,  it  con- 
tinually checks  itself,  and  thus  walks  on  a  foundation  of 
facts.  Hence  the  exercise  it  invokes  does  not  end  in  a 
mere  game  of  intellectual  gymnastics,  such  as  the  ancients 
delighted  in,  but  tends  to  the  mastery  of  Nature.  This 
gradual  conquest  of  the  external  world,  and  the  conscious- 
ness of  augmented  strength  which  accompanies  »it,  render 
the  study  of  Physics  as  delightful  as  it  is  important. 

With  regard  to  the  effect  on  the  imagination,  certain  it 
is  that  the  cool  results  of  physical  induction  furnish  con- 
ceptions which  transcend  the  most  daring  flights  of  that 
faculty.  Take  for  example  the  idea  of  an  all-pervading 
ether  which  transmits  a  tingle,  so  to  speak,  to  the  finger 
ends  of  the  universe  every  time  a  street  lamp  is  lighted. 
The  invisible  billows  of  this  ether  can  be  measured  with  the 
same  ease  and  certainty  as  that  with  which  an  engineer  meas- 
ures a  base  and  two  angles,  and  from  these  finds  the  distance 
across  the  Thames.  Now  it  is  to  be  confessed  that  there 
may  be  just  as  little  poetry  in  the  measurement  of  an  ethe- 
real undulation  as  in  that  of  the  river;  for  the  intellect, 
during  the  acts  of  measurement  and  calculation,  destroys 
those  notions  of  size  which  appeal  to  the  poetic  sense.  It  is 
a  mistake  to  suppose,  with  Dr.  Young,  that 

An  undevout  astronomer  is  mad; 

there  being  no  necessary  connection  between  a  devout 
state  of  mind  and  the  observations  and  calculations  of  a 


ON  THE  STUDY  OF  PHYSICS.  225 

practical  astronomer.  It  is  not  until  the  man  withdraws 
from  his  calculation,  as  a  painter  from  his  work,  and  thus 
realizes  the  great  idea  on  which  lie  has  been  engaged,  that 
imagination  and  wonder  are  excited.  There  is,  I  admit,  a 
possible  danger  here.  If  the  arithmetical  processes  of 
science  be  too  exclusively  pursued,  they  may  impair  the  im- 
agination, and  thus  the  study  of  Physics  is  open  to  the  same 
objection  as  philological,  theological,  or  political  studies, 
when  carried  to  excess.  But  even  in  this  case,  the  injury 
done  is  to  the  investigator  himself:  it  does  not  reach  the 
mass  of  mankind.  Indeed,  the  conceptions  furnished  by 
his  cold,  unimaginative  reckonings  may  furnish  themes  for 
the  poet,  and  excite  in  the  highest  degree  that  sentiment  of 
wonder  which,  notwithstanding  all  its  foolish  vagaries,  table- 
turning  included,  I,  for  my -part,  should  be  sorry  to  see 
banished  from  the  world. 

I  have  thus  far  dwelt  upon  the  study  of  Physics  as  an 
agent  of  intellectual  culture;  but  like  other  things  in 
Nature,  this  study  subserves  more  than  a  single  end.  The 
colors  of  the  clouds  delight  the  eye,  and,  no  doubt,  accom- 
plish moral  purposes  also,  but  the  self-same  clouds  hold 
within  their  fleeces  the  moisture  by  which  our  fields  are 
rendered  fruitful.  The  sunbeams  excite  our  interest  and 
invite  our  investigation;  but  they  also  extend  their  benefi- 
cent influences  to  our  fruits  and  corn,  and  thus  accomplish 
not  only  intellectual  ends,  but  minister,  at  the  same  time, 
to  our  material  necessities.  And  so  it  is  with  scientific  re- 
search. While  the  love  of  science  is  a  sufficient  incentive 
to  the  pursuit  of  science,  and  the  investigator,  in  the  pros- 
ecution of  his  inquiries,  is  raised  above  all  material  con- 
siderations, the  results  of  his  labors  may  exercise  a  potent 
influence  upon  the  physical  condition  of  the  community. 
This  is  the  arrangement  of  Nature,  and  not  that  of  the  scien- 
tific investigator  himself;  for  he  usually  pursues  his  object 
without  regard  to  its  practical  applications. 

And  let  him  who  is  dazzled  by  such  applications — who 
sees  in  the  steam-engine  and  the  electric  telegraph  the 
highest  embodiment  of  human  genius  and  the  only  legiti- 
mate object  of  scientific  research,  beware  of  prescribing 
conditions  to  the  investigator.  Let  him  beware  of  attempt- 
ing to  substitute  for  that  simple  love  with  which  the  votary 
of  science  pursues  his  task,  the  calculations  of  what  he  is 
pleased  to  call  utility.  The  professed  utilitarian  is  unfor- 


226  FRAGMENTS  OF  SCIENCE. 

tunately,  in  most  cases,  the  very  last  man  to  see  the  occult 
sources  from  which  useful  results  are  derived.  He  admires 
the  flower,  but  is  ignorant  of  the  conditions  of  its  growth. 
The  scientific  man  must  approach  Nature  in  his  own  way; 
for  if  you  invade  his  freedom  by  your  so-called  practical 
considerations,  it  may  be  at  the  expense  of  those  qualities 
on  which  his  success  as  a  discoverer  depends.  Let  the  self- 
styled  practical  man  look  to  those  from  the  fecundity  of 
whose  thoughts  he,  and  thousands  like  him,  have  sprung 
into  existence.  Were  they  inspired  in  their  first  inquiries 
by  the  calculations  of  utility?  Not  one  of  them.  They 
were  often  forced  to  live  low  and  lie  hard,  and  to  seek 
compensation  for  their  penury  in  the  delight  which  their 
favorite  pursuits  afforded  them.  In  the  words  of  one  well 
qualified  to  speak  upon  this  subject,  "  I  say  not  merely 
look  at  the  pittance  of  men  like  John  Dalton,  or  the  volun- 
tary starvation  of  the  late  Graff;  but  compare  what  is  con- 
sidered as  competency  or  affluence  by  your  Faradays,  Lie- 
bigs,  and  Herschels,  with  the  expected  results  of  a  life  of 
successful  commercial  enterprise:  then  compare  the  amount 
of  mind  put  forth,  the  work  done  for  society  in  either  case, 
and  you  will  be  constrained  to  allow  that  the  former  belong 
to  a  class  of  workers  who,  properly  speaking,  are  not  paid, 
and  cannot  be  paid  for  their  work,  as  indeed  it  is  of  a  sort 
to  which  no  payment  could  stimulate." 

But  while  the  scientific  investigator,  standing  upon  the 
frontiers  of  human  knowledge,  and  aiming  at  the  conquest 
of  fresh  soil  from  the  surrounding  region  of  the  unknown, 
makes  the  discovery  of  truth  his  exclusive  object  for  the 
time,  he  cannot  but  feel  the  deepest  interest  in  the  practi- 
cal application  of  the  truth  discovered.  There  is  some- 
thing ennobling  in  the  triumph  of  Mind  over  Matter. 
Apart  even  from  its  uses  to  society,  there  is  something  ele- 
vating in  the  idea  of  Man  having  tamed  that  wild  force 
which  flashes  through  the  telegraphic  wire,  and  made  it  the 
minister  of  his  will.  Our  attainments  in  these  directions 
appear  to  be  commensurate  with  our  needs.  We  had  already 
subdued  horse  and  mule,  and  obtained  from  them  all  the 
service  which  it  was  in  their  power  to  render:  we  must 
either  stand  still,  or  find  more  potent  agents  to  execute  our 
purposes.  At  this  point  the  steam-engine  appears.  These 
are  still  new  things;  it  is  not  long  since  we  struck  into  the 
scientific  methods  which  have  produced  these  results.  We 


ON  THE  STUDY  OF  PHYSICS.  227 

cannot  for  an  instant  regard  them  as  the  final  achievements 
of  Science,  but  rather  as  an  earnest  of  what  she  is  yet  to  do. 
They  mark  our  first  great  advances  upon  the  dominion  of 
Nature.  Animal  strength  fails,  but  here  are  the  forces 
which  hold  the  world  together,  and  the  instincts  and  suc- 
cesses of  Man  assure  him  that  these  forces  are  his  when  he 
is  wise  enough  to  command  them. 

As  an  instrument  of  intellectual  culture,  the  study  of 
Physics  is  profitable  to  all;  as  bearing  upon  special  func- 
tions, its  value,  though  not  so  great,  is  still  more  tangible. 
Why,  for  example,  should  members  of  parliament  be 
ignorant  of  the  subjects  concerning  which  they  are  called 
npon  to  legislate?  In  this  land  of  practical  physics,  why 
should  they  be  unable  to  form  an  independent  opinion 
upon  a  physical  question?  Why  should  the  member  of  a 
parliamentary  committee  be  left  at  the  mercy  of  interested 
disputants  when  a  scientific  question  is  discussed,  until  he 
deems  the  nap  a  blessing  which  rescues  him  from  the  be- 
wilderments of  the  committee-room?  The  education 
which  does  not  supply  the  want  here  referred  to,  fails  in 
its  duty  to  England.  Wilh  regard  to  our  working  people, 
in  the  ordinary  sense  of  the  term  working,  the  study  of 
Physics  would,  I  imagine,  be  profitable,  not  only  as  a 
means  of  intellectual  culture,  but  also  as  a  moral  influence 
to  woo  them  from  pursuits  which  now  degrade  them.  A 
man's  reformation  oftener  depends  upon  the  indirect,  than 
upon  the  direct  action  of  the  will.  The  will  must  be 
exerted  in  the  choice  of  employment  which  shall  break  the 
force  of  temptation  by  erecting  a  barrier  against  it.  The 
drunkard,  for  example,  is  in  a  perilous  condition  if  he 
content  himself  merely  with  saying,  or  swearing,  that  he 
will  avoid  strong  drink.  His  thoughts,  if  not  attracted 
by  another  force,  will  revert  to  the  public  house,  and  to 
rescue  him  permanently  from  this,  you  must  give  him  an 
equivalent. 

By  investing  the  objects  of  hourly  intercourse  with  an 
interest  which  prompts  reflection,  new  enjoyments  would 
be  opened  to  the  workingman,  and  every  one  of  these 
would  be  a  point  of  force  to  protect  him  against  tempta- 
tion. Besides  this,  our  factories  and  our  foundries  present 
an  extensive  field  of  observation,  and  were  those  who  work 
in  them  rendered  capable,  by  previous  culture,  of  observing 
what  they  see,,  the  results  might  be  incalculable.  Who 


228  FRAGMENTS  OF  SCIENCE. 

can  say  what  intellectual  Samsons  are  at  the  present 
moment  toiling  with  closed  eyes  in  the  mills  and  forges  of 
Manchester  and  Birmingham?  Grant  these  Samsons 
sight,  and  you  multiply  the  chances  of  discovery,  and  with 
them  the  prospects  of  national  advancement.  In  our 
multitudinous  technical  operations  we  are  constantly  play- 
ing with  forces  our  ignorance  of  which  is  often  the  cause 
of  our  destruction.  There  are  agencies  at  work  in  a 
locomotive  of  which  the  maker  of  it  probably  never 
dreamed,  but  which  nevertheless  may  be  sufficient  to  con- 
vert it  into  an  engine  of  death.  When  we  reflect  on  the 
intellectual  condition  of  the  people  who  work  in  our  coal 
mines,  those  terrific  explosions  which  occur  from  time  to 
time  need  not  astonish  us.  If  these  men  possessed  suf- 
ficient physical  knowledge,  from  the  operatives  themselves 
would  probably  emanate  a  system  by  which  these  shocking 
accidents  might  be  avoided.  Possessed  of  the  knowledge, 
their  personal  interests  would  furnish  the  necessary 
stimulus  to  its  practical  application,  and  thus  two  ends 
would  be  served  at  the  same  time — the  elevation  of  the 
men  and  the  diminution  of  the  calamity. 

Before  the  present  Course  of  Lectures  was  publicly  an- 
nounced, I  had  many  misgivings  as  to  the  propriety  of  my 
taking  a  part  in  them,  thinking  that  my  place  might  be 
better  filled  by  an  older  and  more  experienced  man.  To 
my  experience,  however,  such  as  it  was,  I  resolved  to 
adhere,  and  I  have  therefore  described  things  as  they  re- 
vealed themselves  to  my  own  eyes,  and  have  been  enacted 
in  my  own  limited  practice.  There  is  one  mind  common 
to  us  all;  and  the  true  expression  of  this  mind,  even  in 
small  particulars,  will  attest  itself  by  the  response  which  it 
calls  forth  in  the  convictions  of  my  hearers.  I  ask  your 
permission  to  proceed  a  little  further  in  this  fashion,  and 
to  refer  to  a  fact  or  two  in  addition  to  those  already  cited, 
which  presented  themselves  to  my  notice  during  my  brief 
career  as  a  teacher  in  the  college  already  alluded  to.  The 
facts,  though  extremely  humble,  and  deviating  in  some 
slight  degree  from  the  strict  subject  of  the  present  dis- 
course, may  yet  serve  to  illustrate  an  educational  principle. 

One  of  the  duties  which  fell  to  my  share  was  the  in- 
struction of  a  class  in  mathematics,  and  I  usually  found 
that  Euclid  and  the  ancient  geometry  generally,  when 
properly  and  sympathetically  addressed  to  the  understand- 


ON  THE  STUDY  OF  PHYSICS.  229 

ing,  formed  a  most  attractive  study  for  youth.  But  it  was 
my  habitual  practice  to  withdraw  the  boys  from  the  rou- 
tine of  the  book,  and  to  appeal  to  their  "self-power  in  the 
treatment  of  questions  not  comprehended  in  that  routine. 
At  first,  the  change  from  the  beaten  track  usually  excited 
aversion:  the  youth  felt  like  a  child  amid  strangers;  but  in 
no  single  instance  did  this  feeling  continue.  When  utterly 
disheartened,  I  have  encouraged  the  boy  by  the  anecdote 
of  Newton,  where  he  attributes  the  difference  between  him 
and  other  men  mainly  to  his  own  patience;  or  of  Mirabeau, 
when  he  ordered  his  servant,  who  had  stated  something  to 
be  impossible,  never  again  to  use  that  blockhead  of  a  word. 
Thus  cheered,  the  boy  has  returned  to  his  task  with  a  smile, 
which  perhaps  had  something  of  doubt  in  it,  but  which, 
nevertheless,  evinced  a  resolution  to  try  again.  I  have 
seen  his  eye  brighten,  and,  at  length,  with  a  pleasure  of 
which  the  ecstasy  of  Archimedes  was  but  a  simple  expan- 
sion, heard  him  exclaim,  "I  have  it,  sir."  The  conscious- 
ness of  self-power,  thus  awakened,  was  of  immense  value; 
and,  animated  by  it,  the  progress  of  the  class  was  aston- 
ishing. It  was  often  my  custom  to  give  the  boys  the 
choice  of  pursuing  their  propositions  in  the  book,  or  of 
trying  their  strength  at  others  not  to  be  found  there. 
Never  in  a  single  instance  was  the  book  chosen.  I  was 
ever  ready  to  assist  when  help  was  needful,  but  my  offers 
of  assistance  were  habitually  declined.  The  boys  had  tasted 
the  sweets  of  intellectual  conquest  and  demanded  victories 
of  their  own.  Their  diagrams  were  scratched  on  the  walls, 
cut  into  the  beams  upon  the  playground,  and  numberless 
other  illustrations  were  afforded  of  the  living  interest  they 
took  in  the  subject.  For  my  own  part,  as  far  as  experience 
in  teaching  goes,  I  was  a  mere  fledgling — knowing  nothing 
of  the  rules  of  pedagogics,  as  the  Germans  name  it;  but 
adhering  to  the  spirit  indicated  at  the  commencement  of 
this  discourse,  and  endeavoring  to  make  geometry  a  means 
rather  than  a  branch  of  education.  The  experiment  was 
successful,  and  some  of  the  most  delightful  hours  of  my 
existence  have  been  spent  in  marking  the  vigorous  and 
cheerful  expansion  of  mental  power,  when  appealed  to  in 
the  manner  here  described. 

Our  pleasure  was  enhanced  when  we  applied  our  math- 
ematical knowledge  to  the  solution  of  physical  problems. 
Many  objects  of  hourly  contact  had  thus  a  new  interest  and 


230  fRA  OMENTS  0 F  SCIENCE. 

significance  imparted  to  them.  The  swing,  the  see-saw; 
the  tension  of  the  giant-stride  ropes,  the  fall  and  rebound 
of  the  football,  the  advantage  of  a  small  boy  over  a  large 
one  when  turning  short,  particularly  in  slippy  weather;  all 
became  subjects  of  investigation.  A  lady  stands  before  a 
looking-glass,  of  her  own  height;  it  was  required  to  know 
how  much  of  the  glass  was  really  useful  to  her?  We 
learned  with  pleasure  the  economic  fact  that  she  might 
dispense  with  the  lower  half  and  see  her  whole  figure  not- 
withstanding. It  was  also  pleasant  to  prove  bv  mathe- 
matics, and  verify  by  experiment,  that  the  angular  velocity 
of  a  reflected  beam  is  twice  that  of  the  mirror  which 
reflects  it.  From  the  hum  of  a  bee  we  were  able  to  deter- 
mine the  number  of  times  the  insect  flaps  its  wings  in  a 
second.  Following  up  our  researches  upon  the  pendulum, 
we  learned  how  Colonel  Sabine  had  made  it  the  means  of 
determining  the  figure  of  the  earth;  and  we  were  also 
startled  by  the  inference  which  the  pendulum  enabled  us 
to  draw,  that  if  the  diurnal  velocity  of  the  earth  were 
seventeen  times  its  present  amount,  the  centrifugal  force 
at  the  equator  would  be  precisely  equal  to  the  force  of 
gravitation,  so  that  an  inhabitant  of  those  regions  would 
then  have  the  same  tendency  to  fall  upward  as  down- 
ward. All  these  things  were  sources  of  wonder  and  de- 
light to  us:  and  when  we  remembered  that  we  were  gifted 
with  the  powers  which  had  reached  such  results,  and  that 
the  same  great  field  was  ours  to  work  in,  our  hopes  arose 
that  at  some  future  day  we  might  possibly  push  the  subject 
a  little  further,  and  add  our  own  victories  to  the  conquests 
already  won. 

I  ought  to  apologize  to  you  for  dwelling  so  long  upon 
this  subject;  but  the  days  spent  among  these  young 
philosophers  made  a  deep  impression  on  me.  I  learned 
among  them  something  of  myself  and  of  human  nature, 
and  obtained  some  notion  of  a  teacher's  vocation.  If  there 
be  one  profession  in  England  of  paramount  importance, 
I  believe  it  to  be  that  of  the  schoolmaster;  and  if  there  be 
a  position  where  selfishness  and  incompetence  do  most  seri- 
ous mischief,  by  lowering  the  moral  tone  and  exciting 
irreverence  and  cunning  where  reverence  and  noble  truth- 
fulness ought  to  be  the  feelings  evoked,  it  is  that  of  the 
principal  of  a  school.  When  a  man  of  enlarged  heart  and 
mind  comes  among  boys — when  he  allows  his  spirit  to 


ON  THE  STUDY  OF  PHYSICS.  231 

stream  through  them,  and  observes  the  operation  of  his 
own  character  evidenced  in  the  elevation  of  theirs — it 
would  be  idle  to  talk  of  the  position  of  such  a  man  being 
honorable.  It  is  a  blessed  position.  The  man  is  a  bless- 
ing to  himself  and  to  all  around  him.  Such  men,  I  be- 
lieve, are  to  be  found  in  England,  and  it  behoves  those 
who  busy  themselves  with  the  mechanics  of  education  at 
the  present  day,  to  seek  them  out.  For  no  matter  what 
means  of  culture  may  be  chosen,  whether  physical  or 
philological,  success  must  ever  mainly  depend  upon  the 
amount  of  life,  love,  and  earnestness,  which  the  teacher 
himself  brings  with  him  to  his  vocation. 

Let  me  again,  and  finally,  remind  you  that  the  claims 
of  that  science  which  finds  in  me  to-day  its  unripened 
advocate,  are  those  of  the  logic  of  Nature  upon  the  reason 
of  her  child — that  its  disciplines,  as  an  agent  of  culture, 
are  based  upon  the  natura'  relations  subsisting  befween 
Man  and  the  universe  of  which  he  forms  a  part.  On  the 
one  side,  we  have  the  apparently  lawless  shifting  of 
phenomena;  on  the  other  side,  mind,  which  requires  law 
for  its  equilibrium,  and  through  its  own  indestructible 
instincts,  as  well  as  through  the  teachings  of  experience, 
knows  that  these  phenomena  are  reducible  to  law.  To 
chasten  this  apparent  chaos  is  a  problem  which  man  has 
set  before  him.  The  world  was  built  in  order:  and  to  us 
are  trusted  the  will  and  power  to  discern  its  harmonies, 
and  to  make  them  the  lessons  of  our  lives.  From  the 
cradle  to  the  grave  we  are  surrounded  with  objects  which 
provoke  inquiry.  Descending  for  a  moment  from  this  high 
plea  to  considerations  which  lie  closer  to  us  as  a  nation — 
as  a  land  of  gas  and  furnaces,  of  steam  and  electricity:  as 
a  land  which  science,  practically  applied,  has  made  great 
in  peace  and  mighty  in  war:  I  ask  you  whether  this  "  land 
of  old  and  just  renown"  has  not  a  right  to  expect  from 
her  institutions  a  culture  more  in  accordance  with  her 
present  needs  than  that  supplied  by  declension  and  con- 
jugation? And  if  the  tendency  should  be  to  lower  the 
estimate  of  science,  by  regarding  it  exclusively  as  the 
instrument  of  material  prosperity,  let  it  be  this  high  mis- 
sion of  our  universities  to  furnish  the  proper  counterpoise 
bv  pointing  out  its  nobler  uses — lifting  the  national  mind 
to  the  contemplation  of  it  as  the  last  development  of  that 
''increasing  purpose  "  which  runs  through  the  ages  and 
widens  the  thoughts  of  men. 


232  FRAGMENTS  OF  SCIENCE. 

CHA.PTEE  XII. 

ON   CRYSTALLINE   AND   SLATY   CLEAVAGE.* 

WHEN  the  student  of  physical  science  has  to  investigate 
the  character  of  any  natural  force,  his  first  care  must  be  to 
purify  it  from  the  mixture  of  other  forces,  and  thus  study 
its  simple  action.  If,  for  exam  pie,  he  wishes  to  know  how 
a  mass  of  liquid  would  shape  itself  if  at  liberty  to  follow 
the  bent  of  its  own  molecular  forces,  he  must  see  that 
these  forces  have  free  and  undisturbed  exercise.  We 
might  perhaps  refer  him  to  the  dewdrop  for  a  solution  of 
the  question;  but  here  we  have  to  do,  not  only  with  the 
action  of  the  molecules  of  the  liquid  upon  each  other,  but 
also  with  the  action  of  gravity  upon  the  mass,  which  pulls 
the  drop  downward  and  elongates  it.  If  he  would  examine 
the  problem  in  its  purity,  he  must  do  as  Plateau  has  done, 
detach  the  liquid  mass  from  the  action  of  gravity;  he 
would  then  find  the  shape  to  be  a  perfect  sphere.  Natural 
processes  come  to  us  in  a  mixed  manner,  and  to  the  un- 
instructed  mind  are  a  mass  of  unintelligible  confusion. 
Suppose  half  a  dozen  of  the  best  musical  performers  to  be 
placed  in  the  same  room,  each  playing  his  own  instrument 
to  perfection,  but  no  two  playing  the  same  tune;  though 
each  individual  instrument  might  be  a  source  of  perfect 
music,  still  the  mixture  of  all  would  produce  mere  noise. 
Thus  it  is  with  the  processes  of  nature,  where  mechanical 
and  molecular  laws  intermingle  and  create  apparent  con- 
fusion. Their  mixture  constitutes  what  may  be  called  the 
noise  of  natural  laws,  and  it  is  the  vocation  of  the  man  of 
science  to  resolve  this  noise  into  its  components,  and  thus 
to  detect  the  underlying  music. 

The  necessity  of  this  detachment  of  one  force  from  all 
other  forces  is  nowhere  more  strikingly  exhibited  than  in 
the  phenomena  of  crystallization.  Here,  for  example,  is  a 
solution  of  common  sulphate  of  soda  or  Glauber  salt. 
Looking  into  it  mentally,  we  see  the  molecules  of  that 
liquid,  like  disciplined  squadrons  under  a  governing  eye, 
arranging  themselves  into  battalions,  gathering  round  dis- 
tinct centers,  and  forming  themselves  into  solid  masses, 

*  From  a  discourse  delivered  in  the  Royal  Institution  of  Great 
Britain,  June  6,  1856. 


ON  CRYSTALLINE  AND  SLAT7  CLEA  VAQE.      233 

which  after  a  time  assume  the  visible  shape  of  the  crystal 
now  held  iu  my  hand.  I  may,  like  au  ignorant  meddler 
wishing  to  hasten  matters,  introduce  confusion  into  this 
order.  This  may  be  done  by  plunging  a  glass  rod  into  the 
vessel;  the  consequent  action  is  not  the  pure  expression  of 
the  crystalline  forces;  the  molecules  rush  together  with  the 
confusion  of  an  unorganized  mob,  and  not  with  the  steady 
accuracy  of  a  disciplined  host.  In  this  mass  of  bismuth 
also  we  have  an  example  of  confused  crystallization;  but 
in  the  crucible  behind  me  a  slower  process  is  going  on: 
here  there  is  an  architect  at  work  "  who  makes  no  chips, 
no  din,"  and  who  is  now  building  the  particles  into 
crystals,  similar  in  shape  and  structure  to  those  beautiful 
masses  which  we  see  upon  the  table.  By  permitting  alum 
to  crystallize  in  this  slow  way,  we  obtain  these  perfect 
octahedrons;  by  allowing  carbonate  of  lime  to  crystallize, 
nature  produces  these  beautiful  rhomboids;  when  silica 
crystallizes,  we  have  formed  these  hexagonal  prisms  capped 
at  the  ends  by  pyramids;  by  allowing  saltpeter  to  crystallize 
we  have  these  prismatic  masses,  and  when  carbon  crystal- 
lizes, we  have  the  diamond.  If  we  wish  to  obtain  a  per- 
fect crystal  we  must  allow  the  molecular  forces  free  play; 
if  the  crystallizing  mass  be  permitted  to  rest  upon  a  sur- 
face it  will  be  flattened,  and  to  prevent  this  a  small  crystal 
must  be  so  suspended  as  to  bs  surrounded  on  all  sides  by 
the  liquid,  or,  if  it  rest  upon  the  surface,  it  must  be  turned" 
daily  so  as  to  present  all  its  faces  in  succession  to  the 
working  builder. 

In  building  up  crystals  these  little  atomic  bricks  often 
arrange  themselves  into  layers  which  are  perfectly  parallel 
to  each  other,  and  which  can  be  separated  by  mechanical 
means;  this  is  called  the  cleavage  of  the  crystal.  The 
crystal  of  sugar  I  hold  in  my  hand  has  thus  far  escaped 
the  solvent  and  abrading  forces  which  sooner  or  later 
determine  the  fate  of  sugar-candy.  I  readily  discover  that 
it  cleaves  with  peculiar  facility  in  one  direction.  Again  I 
lay  my  knife  upon  this  piece  of  rocksalt,  and  with  a  blow 
cleave  it  in  one  direction.  Laying  the  knife  at  right 
angles  to  its  former  position,  the  crystal  cleaves  again;  and 
finally  placing  the  knife  at  right  angles  to  the  two  former 
positions,  we  find  a  third  cleavage.  Rocksalt  cleaves  in 
three  directions  and  the  resulting  solid  is  this  perfect  cube, 
•which  may  be  broken  up  into  any  number  of  smaller  cubes. 


234  FRAGMENTS  OF  SVlENCW. 

Iceland  spar  also  cleaves  in  three  directions,  not  at  right 
angles,  but  oblique  to  each  other,  the  resulting  solid  being 
a  rhomboid.  In  each  of  these  cases  the  mass  cleaves  with 
equal  facility  in  all  three  directions.  For  the  sake  of  com- 
pleteness I  mav  say  that  many  crystals  cleave  with  unequal 
facility  in  different  directions:  heavy  spar  presents  an 
example  of  this  kind  of  cleaVage. 

Turn  we  now  to  the  consideration  of  some  other  phenom- 
ena to  which  the  term  cleavage  may  be  applied.  Beech, 
deal,  and  other  woods  cleave  with  facility  along  the  fiber, 
and  this  cleavage  is  most  perfect  when  the  edge  of  the  axe 
is  laid  across  the  rings  which  mark  the  growth  of  the  tree. 
If  you  look  at  this  bundle  of  hay  severed  from  a  rick,  you 
will  see  a  sort  of  cleavage  in  it  also;  the  stalks  lie  in  hori- 
zontal planes,  and  only  a  small  force  is  required  to  separate 
them  laterally.  But  we  cannot  regard  the  cleavage  of  the 
tree  as  the  same  in  character  as  that  of  the  hayrick.  In 
the  one  case  it  is  the  molecules  arranging  themselves  accord- 
ing to  organic  laws  which  produce  a  cleavable  structure,  in 
the  other  case  the  easy  separation  in  one  direction  is  due  to 
the  mechanical  arrangement  of  the  coarse  sensible  stalks 
of  hay. 

This  sandstone  rock  was  once  a  powder  held  in  mechan- 
ical suspension  by  water.  The  powder  was  composed  of  two 
distinct  parts,  fine  grains  of  sand  and  small  plates  of  mica. 
Imagine  a  wide  strand  covered  by  a  tide,  or  an  estuary 
with  water  which  holds  such  powder  in  suspension:  how 
will  it  sink?  The  rounded  grains  of  sand  will  reach  the 
bottom  first,  because  they  encounter  least  resistance,  the 
mica  afterward,  and  when  the  tide  recedes  we  have  the  little 
plates  shining  like  spangles  upon  the  surface  of  the  sand. 
Each  successive  tide  brings  its  charge  of  mixed  powder, 
deposits  its  duplex  layer  day  after  day,  and  finally  masses 
of  immense  thickness  are  piled  up,  which  by  preserving 
the  alternations  of  sand  and  mica,  tell  the  tale  of  their 
formation.  Take  the  sand  and  mica,  mix  them  together  in 
water,  and  allow  them  to  subside;  they  will  arrange  them- 
selves in  the  manner  indicated,  and  by  repeating  the  proc- 
ess you  can  actually  build  up  a  mass  which  shall  be  the 
exact  counterpart  of  that  presented  by  nature.  Now  this 
structure  cleaves  with  readiness  along  the  planes  in  which 
the  particles  of  mica  are  strewn.  Specimens  of  such  a  rock 
sent  to  me  from  Halifax,  and  other  masses  from  the 


ON  OR  7STA  LLINE  AND  SLA  TT  OLE  A  VA  GE.     235 

quarries  of  Over  Darwen  in  Lancashire,  are  here  before 
you.  With  a  hammer  and  chisel  I  can  cleave  them  into 
flags;  indeed  these  flags  are  employed  for  roofing  purposes 
in  the  districts  from  which  the  specimens  have  come,  and 
receive  the  name  of  "  slatestone."  But  you  will  discern 
without  a  word  from  me,  that  this  cleavage  is  not  a  crystal- 
line cleavage  any  more  than  that  of  a  hayrick  is.  It  is 
molar,  not  molecular. 

This,  so  far  as  I  am  aware  of,  has  never  been  imagined, 
and  it  has  been  agreed  among  geologists  not  to  call  such 
splitting  as  this  cleavage  at  all,  but  to  restrict  the  term  to  a 
phenomenon  of  a  totally  different  character. 

Those  who  have  visited  the  slate  quarries  of  Cumberland 
and  North  Wales  will  have  witnessed  the  phenomenon  to 
which  1  refer.  We  have  long  drawn  our  supply  of  roofing- 
slates  from  such  quarries;  schoolboys  ciphered  on  these 
slates,  they  were  used  for  tombstones  in  churchyards,  and 
for  billiard- tables  in  the  metropolis;  but  not  until  a  com- 
paratively late  period  did  men  begin  to  inquire  how  their 
wonderful  structure  is  produced.  What  is  the  agency 
which  enables  us  to  split  Honister  Crag,  or  the  cliffs  of 
Snowdon,  into  laminae  from  crown  to  base?  This  question 
is  at  the  present  moment  one  of  the  great  difficulties  of 
geologists,  and  occupies  their  attention  perhaps  more  than 
any  other.  You  may  wonder  at  this.  Looking  into  the 
quarry  of  Penrhyn,  you  may  be  disposed  to  offer  the 
explanation  I  heard  given  two  years  ago.  "  These  p] 


explanation  I  heard  given  two  years  ago.  "  These  ph 
of  cleavage,"  said  a  friend  who  stood  beside  me  on  the 
quarry's  edge,  "are  the  planes  of  stratification  which  have 
been  lifted  by  some  convulsion  into  an  almost  vertical  posi- 
tion." But  this  was  a  mistake,  and  indeed  here  lies,  the 
grand  difficulty  of  the  problem.  The  planes  of  cleavage 
stand  in  most  cases  at  a  high  angle  to  the  bedding.  Thanks 
to  Sir  Roderick  Murchison,  I  am  able  to  place  the  proof 
of  this  before  you.  Here  is  a  specimen  of  slate  in  which 
both  the  planes  of  cleavage  and  of  bedding  are  distinctly 
marked,  one  of  them  making  a  large  angle  with  the  other. 
This  is  common.  The  cleavage  of  slates  then  is  not  a  ques- 
tion of  stratification;  what  then  is  its  cause? 

In  an  able  and  elaborate  essay  published  in  1835,  Pro- 
fessor Sedgwick  proposed  the  theory  that  cleavage  is  due  to 
the  action  of  crystalline  or  polar  forces  subsequent  to  the 
consolidation  of  the  rock.  "  We  may  affirm,"  he  says, 


236  FRAGMENTS  OF  8C1RNCB. 

"  that  no  retreat  of  the  parts,  no  contraction  of  dimensions 
in  passing  to  a  solid  state,  can  explain  such  phenomena. 
They  appear  to  me  only  resolvable  on  the  supposition  that 
crystalline  or  polar  forces  acted  upon  the  ~whole  mass 
simultaneously  in  one  direction  and  with  adequate  force." 
And  again,  in  another  place:  "  Crystalline  forces  have  re- 
arranged whole  mountain  masses,  producing  a  beautiful 
crystalline  cleavage,  passing  alike  through  afl  the  strata."* 
The  utterance  of  such  a  man  struck  deep,  as  it  ought  to  do, 
into  the  minds  of  geologists,  and  at  the  present  day  there 
are  few  who  do  not  entertain  this  view,  either  in  whole  or 
in  part.f  The  boldness  of  the  theory,  indeed,  has,  in  some 
cases,  caused  speculation  to  run  riot,  and  we  have  books 
published  on  the  action  of  polar  forces  and  geologic 
magnetism,  which  rather  astonish  those  who  know  some- 
thing about  the  subject.  According  to  this  theory  whole 
districts  of  North  Wales  and  Cumberland,  mountains 
included,  are  neither  more  nor  less  than  the  parts  of  a 
gigantic  crystal.  These  masses  of  slate  were  originally  fine 
mud,  composed  of  the  broken  and  abraded  particles  of 
older  rocks.  They  contain  silica,  alumina,  potash,  soda, 
and  mica  mixed  mechanically  together.  In  the  course  of 
ages  the  mixture  became  consolidated,  and  the  theory  be- 
fore us  assumes  that  a  process  of  crystallization  afterward 
rearranged  the  particles  and  developed  in  it  a  single 
plane  of  cleavage.  Though  a  bold,  and  I  think  inadmis- 
sible, stretch  of  analogies,  this  hypothesis  has  done  good 
service.  Right  or  wrong,  a  thoughtfully  uttered  theory  has 
a  dynamic  power  which  operates  against  intellectual  stag- 
nation; and  even  by  provoking  opposition  is  eventually  of 
service  to  the  cause  of  truth.  It  would,  however,  have 
been  remarkable  if,  among  the  ranks  of  geologists  them- 

*  Transactions  of  the  Geological  Society ,  ser.  ii.,  vol.  Hi.,  p.  477. 

f  In  a  letter  to  Sir  Charles  Lyell,  dated  from  the  Cape  of  Good 
Hope,  February  20.  1836,  Sir  John  Herschel  writes  as  follows:  "  If 
rocks  have  been  so  heated  as  to  allow  of  a  commencement  of  crys- 
tallization, that  is  to  say,  if  they  have  been  heated  to  a  point  at 
which  the  particles  can  begin  to  move  among  themselves,  or  at  least 
on  their  own  axes,  some  general  law  must  then  determine  the  posi- 
tion in  which  these  particles  will  rest  on  cooling.  Probably  that 
position  will  have  some  relation  to  the  direction  in  which  the  heat 
escapes.  Now  when  all  or  a  majority  of  particles  of  the  same  nature 
have  a  general  tendency  to  one  position,  that  must  of  course  deter- 
mine a  cleavage  plane." 


ON  CR TSTALLINE  AND  SLA TT  CLEA  VAGE.      237 

selves,  men  were  not  found  to  seek  an  explanation  of  slate- 
cleavage  involving  a  less  hardy  assumption. 

The  first  step  in  an  inquiry  of  this  kind  is  to  seek  facts. 
This  has  been  done,  and  the  labors  of  Daniel  Sharpe  (the 
late  president  of  the  Geological  Society,  who,  to  the  loss  of 
science  and  the  sorrow  of  all  who  knew  him,  has  so  sud- 
denly been  taken  away  from  us),  Mr.  Henry  Clifton  Sorby, 
and  "others,  have  furnished  us  with  a  body  of  facts 
associated  with  slaty  cleavage,  and  having  a  most  important 
bearing  upon  the  question. 

Fossil  shells  are  found  in  these  slate-rocks.  I  have 
here  several  specimens  of  such  shells  in  the  actual  rock, 
and  occupying  various  positions  in  regard  to  the  cleavage 
planes.  They  are  squeezed,  distorted,  and  crushed;  in 
all  cases  the  distortion  leads  to  the  inference  that  the 
rock  which  contains  these  shells  has  been  subjected  to 
enormous  pressure  in  a  direction  at  right  angles  to  the 
planes  of  cleavage.  The  shells  are  all  flattened  and  spread 
out  in  these  planes.  Compare  this  fossil  trilobite  of  normal 
proportions  with  these  others  which  have  suffered  distor- 
tion. Some  have  lain  across,  some  along,  and  some  oblique 
to  the  cleavage  of  the  slate  in  which  they  are  found;  but  in 
all  cases  the  distortion  is  such  as  required  for  its  production 
a  compressing  force  acting  at  right  angles  to  the  planes  of 
cleavage.  As  the  trilobites  lay  in  the  mud,  the  jaws  of  a 
gigantic  vise  appear  to  have  closed  upon  them  and  squeezed 
them  into  the  shapes  you  see. 

We  sometimes  find  a  thin  layer  of  coarse  gritty  material, 
between  two  layers  of  finer  rock,  through  which  and  across 
the  gritty  layer  pass  the  planes  of  lamination.  The  coarse 
layer  is  found  bent  by  the  pressure  into  sinuosities  like  a 
contorted  ribbon.  Mr.  Sorby  has  described  a  striking  case 
of  this  kind.  This  crumpling  can  be  experimentally  imi- 
tated; the  amount  of  compression  might,  moreover,  be 
roughly  estimated  by  supposing  the  contorted  bed  to  be 
stretched  out,  its  length  measured  and  compared  with 
the  shorter  distance  into  which  it  has  been  squeezed.  We 
find  in  this  way  that  the  yielding  of  the  mass  has  been 
considerable. 

Let  me  now  direct  your  attention  to  another  proof  of 
pressure;  you  see  the  varying  colors  which  indicate  the 
bedding  on  this  mass  of  slate.  The  dark  portion  is  gritty, 
being  composed  of  comparatively  coarse  particles,  which. 


238  FRAGMENTS  OF  SCIENCE. 

owing  to  their  size,  shape  and  gravity,  sink  first  and  con- 
stitute the  bottom  of  each  layer.  Gradually,  from  bottom 
to  top  the  coarseness  diminishes,  and  near  the  upper  surface 
we  have  a  layer  of  exceedingly  fine  grain.  It  is  the  fine 
mud  thus  consolidated  from  which  are  derived  the  German 
razor-stones,  so  much  prized  for  the  sharpening  of  surgical 
instruments.  When  a  bed  is  thin,  the  fine-grain  slate  is 
permitted  to  rest  upon  a  slab  of  the  coarse  slate  in  contact 
with  it;  when  the  fine  bed  is  thick,  it  is  cut  into  slices 
which  are  cemented  to  pieces  of  ordinary  slate,  and  thus 
rendered  stronger.  The  mud  thus  deposited  is,  as  might 
be  expected,  often  rolled  up  into  nodular  masses,  carried 
forward,  and  deposited  among  coarser  material  by  the  rivers 
from  which  the  slate-mud  has  subsided.  Here  are  such 
nodules  enclosed  in  sandstone.  Everybody,  moreover,  who 
has  ciphered  upon  a  school-slate  must  remember  the 
whitish-green  spots  which  sometimes  dotted  the  surface  of 
the  slate,  and  over  which  the  pencil  usually  slid  as  if  the 
spots  were  greasy.  Now  these  spots  are  composed  of  the 
finer  mud,  and  they  could  not,  on  account  of  their  fineness, 
bite  the  pencil  like  the  surrounding  gritty  portions  of  the 
slate.  Here  is  a  beautiful  example  of  these  spots:  you 
observe  them,  on  the  cleavage  surface,  in  broad  round 
patches.  But  turn  the  slate  edgeways  and  the  section  of 
each  nodule  is  seen  to  be  a  sharp  oval  with  its  longer  axis 
parallel  to  the  cleavage.  This  instructive  fact  has  been 
adduced  by  Mr.  Sorby.  I  have  made  excursions  to  the 
quarries  of  Wales  and  Cumberland,  and  to  many  of  the 
slate  yards  of  London,  and  found  the  fact  general.  Thus 
we  elevate  a  common  experience  of  our  boyhood  into 
evidence  of  the  highest  significance  as  regards  a  most  im- 
portant geological  problem.  From  the  magnetic  deport- 
ment of  these  slates,  I  was  led  to  infer  that  these  spots  con- 
tain a  less  amount  of  iron  than  the  surrounding  dark  slate. 
An  analysis  was  made  for  me  by  Mr.  Hambly  in  the 
laboratory  of  Dr.  Percy  at  the  School  of  Mines  with  the 
following  result: 

ANALYSIS  OP  SLATE. 
Dark  Slate,  two  analyses. 

1.  Percentage  ot  iron 5.85 

2.  "  " 6.13 

Mean.  5.99 


ON  CR  YSTALLINE  AND  .SLA TT  GLEA  VAOE.      239 

Whitish  Green  Slate. 

1.  Percentage  of  iron 3.24 

2.  " 3  13- 

Mean .        .         3.18 

According  to  these  analyses  the  quantity  of  iron  in  the 
dark  slate  immediately  adjacent  to  the  greenish  spot  is 
nearly  double  the  quantity  contained  in  the  spot  itself. 
This  is  about  the  proportion  which  the  magnetic  experi- 
ments suggested. 

Let  me  now  remind  you  that  the  facts  brought  before 
you  are  typical — each  is  the  representative  of  a  class.  We 
have  seen  shells  crushed,  the  trilobites  squeezed,  beds  con- 
torted, nodules  of  greenish  marl  flattened;  and  all  these 
sources  of  independent  testimony  point  to  one  and  the 
same  conclusion,  namely,  that  slate-rocks  have  been  sub- 
jected to  enormous  pressure  in  a  direction  at  right  angles 
to  the  planes  of  cleavage. 

In  reference  to  Mr.  Sorby's  contorted  bed,  I  have  said 
that  by  supposing  it  to  be  stretched  out  and  its  length 
measured,  it  would  give  us  an  idea  of  the  amount  of  yield- 
ing of  the  mass  above  and  below  the  bed.  Such  a  measure- 
ment, however,  would  not  give  the  exact  amount  of  yield- 
ing. I  hold  in  my  hand  a  specimen  of  slate  with  its  bed- 
ding marked  upon  it;  the  lower  portions  of  each  layer  being 
composed  of  a  comparatively  coarse  gritty  material  some- 
thing like  what  you  may  suppose  the  contorted  bed  to  be 
composed  of.  Now,  in  crossing  these  gritty  portions,  the 
cleavage  turns,  as  if  tending  to  cross  the  bedding  at 
another  angle.  When  the  pressure  began  to  act,  the  inter- 
mediate bed,  which  is  not  entirely  unyielding,  suffered 
longitudinal  pressure;  as  it  bent,  the  pressure  became 
gradually  more  transverse,  and  the  direction  of  its  cleav- 
age is  exactly  such  as  you  would  infer  from  an  action  of 
this  kind — it  is  neither  quite  across  the  bed,  nor  yet  in  the 
same  direction  as  the  cleavage  of  the  slate  above  and  below 
it,  but  intermediate  between  both.  Supposing  the  cleav- 
age to  be  at  right  angles  to  the  pressure,  this  is  the 
direction  which  it  ought  to  take  across  these  more  unyield- 
ing strata. 

Thus  we  have  established  the  concurrence  of  the  phenom- 
ena of  cleavage  and  pressure — that  they  accompany  each 
other]  but  the  question  still  remains.  Is  the  pressure  suffi- 


240  FRAGMENTS  OF  SCIENCE. 

cient  to  account  for  the  cleavage?  A  single  geologist,  as 
far  as  I  am  aware,  answers  boldly  in  the  affirmative.  This 
geologist  is  Sorby,  who  has  attacked  the  question  in  the 
true  spirit  of  a  physical  investigator.  Call  to  mind  the 
cleavage  of  the  flags  of  Halifax  and  Over  Darvven,  which  is 
caused  by  the  interposition  of  layers  of  mica  between  the 
gritty  strata.  Mr.  Sorby  finds  plates  of  rnica  to  be  also  a 
constituent  of  slate-rock.  He  asks  himself,  what  will  be 
the  effect  of  pressure  upon  a  mass  containing  such  plates 
confusedly  mixed  up  in  it?  It  will  be,  he  argues,  and  he 
argues  rightly,  to  place  the  plates  with  their  flat  surfaces 
more  or  less  perpendicular  to  the  direction  in  which  the 
pressure  is  exerted.  He  takes  scales  of  the  oxide  of  iron, 
mixes  them  with  a  fine  powder,  and  on  squeezing  the  mass 
finds  that  the  tendency  of  the  scales  is  to  set  themselves  at 
right  angles  to  the  line  of  pressure.  Along  the  planes  of 
weakness  produced  by  the  scales  the  mass  cleaves. 

By  tests  of  a  different  character  from  those  applied  by 
Mr.  Sorby,  it  might  be  shown  how  true  his  conclusion  is — 
that  the  effect  of  pressure  on  elongated  particles,  or  plates, 
will  be  such  as  he  describes  it.  But  while  the  scales  must 
be  regarded  as  a  true  cause,  I  should  not  ascribe  to  them  a 
large  share  in  the  production  of  the  cleavage.  I  believe 
that  even  if  the  plates  of  mica  were  wholly  absent,  the 
cleavage  of  slate-rocks  would  be  much  the  same  as  it  is  at 
present. 

Here  is  a  mass  of  pure  white  wax;  it  contains  no  mica 
particles,  no  scales  of  iron,  or  anything  analogous  to  them. 
Here  is  the  selfsame  substance  submitted  to  pressure.  I 
would  invite  the  attention  of  the  eminent  geologists  now 
before  me  to  the  structure  of  this  wax.  No  slate  ever  ex- 
hibited so  clean  a  cleavage;  it  splits  into  laminae  of  sur- 
passing tenuity,  and  proves  at  a  single  stroke  that  pressure 
is  sufficient  to  produce  cleavage,  and  that  this  cleavage  is 
independent  of  intermixed  plates  or  scales.  I  have  pur- 
posely mixed  this  wax  with  elongated  particles,  and  am 
unable  to  say  at  the  present  moment  that  the  cleavage  is 
sensibly  affected  by  their  presence — if  anything,  I  should 
say  they  rather  impair  its  fineness  and  clearness  than 
promote  it. 

The  finer  the  slate  is  the  more  perfect  will  be  the  resem- 
blance of  its  cleavage  to  that  of  the  wax.  Compare  the 
surface  of  the  wax  with  the  surface  of  this  slate  from  Bor- 


ON  OR TSTA LLTNtt  AND  SLA TY  CLEA  VAGE.     34! 

rod  ale  in  Cumberland.  You  have  precisely  the  same  fea- 
tures in  both;  you  see  flakes  clinging  to  the  surfaces  of 
each,  which  have  been  partially  torn  away  in  cleaving. 
Let  any  close  observer  compare  these  two  effects,  he  will, 
I  am  persuaded,  be  led  to  the  conclusion  that  they  are  the 
product  of  a  common  cause.* 

But  you  will  ask  me  how,  according  to  my  view,  does 
pressure  produce  this  remarkable  result?  This  may  be 
stated  in  a  very  few  words. 

There  is  no  such  thing  in  nature  as  a  body  of  perfectly 
homogeneous  structure.  I  break  this  clay  which  seems  so 
uniform,  and  find  that  the  fracture  presents  to  my  eyes  in- 
numerable surfaces  along  which  it  has  given  way,  and  it 
has  yielded  along  those  surfaces  because  in  them  the  cohe- 
sion of  the  mass  is  less  than  elsewhere.  I  break  this  mar- 
ble, and  even  this  wax,  and  observe  the  same  result;  look 
at  the  mud  at  the  bottom  of  a  dried  pond;  look  at  some  of 
the  ungraveled  walks  in  Kensington  Gardens  on  drying 
after  rain — they  are  cracked  and  split,  and  other  circum- 
stances being  equal,  they  crack  and  split  where  the  cohesion 
is  a  minimum.  Take  then  a  mass  of  partially  consol- 
idated mud.  Such  a  mass  is  divided  and  subdivided  by 
interior  surfaces  along  which  the  cohesion  is  comparatively 
small.  Penetrate  the  mass  in  idea,  and  you  will  see  it  com- 
posed of  numberless  irregular  polyhedra  bounded  by  surfaces 
of  weak  cohesion.  Imagine  such  a  mass  subjected  to  pres- 
sure— it  yields  and  spreads  out  in  the  direction  of  least 
resistance;!  the  little  polyhedra  become  converted  into 
lamina?,  separated  from  each  other  by  surfaces  of  weak 
cohesion,  and  the  infallible  result  will  be  a  tendency  to 
cleave  at  right  angles  to  the  line  of  pressure. 

*  I  Lave  usually  softened  the  wax  by  warming  it,  kneaded  it  with 
the  fingers,  and  pressed  it  between  thick  plates  of  glass  previously 
wetted.  At  the  ordinary  summer  temperature  the  pressed  wax  is 
soft,  and  tears  rather  than  cleaves;  on  this  account  I  cool  my  com- 
pressed specimens  in  a  mixture  of  pounded  ice  and  salt,  and  when 
thus  cooled  they  split  cleanly. 

f  It  is  scarcely  necessary  to  say  that  if  the  mass  were  squeezed 
equally  in  all  directions  no  laminated  structure  could  be  produced  ; 
it  must  have  room  to  yield  in  a  lateral  direction.  Mr.  Warren  De  la 
Rue  informs  me  that  he  once  wished  to  obtain  white-lead  in  a  fine 
granular  state,  and  to  accomplish  this  he  first  compressed  it.  The 
mold  was  conical,  and  permitted  the  lead  to  spread  out  a  little  later- 
ally. The  lamination  was  as  perfect  as  that  of  slate,  and  it  quite 
defeated  Mm  in  his  effort  to  obtain  a  granular  powder. 


242  #&4  GMENTS  0  V  8UTENCK. 

Further,  a  mass  of  dried  mud  is  full  of  cavities  and  fis- 
sures. If  you  break  dried  pipe-clay  you  see  them  in  great 
numbers,  and  there  are  multitudes  of  them  so  small  that 
you  cannot  see  them.  A  flattening  of  these  cavities  must 
take  place  in  squeezed  mud,  and  this  must  to  some  extent 
facilitate  the  cleavage  of  the  mass  in  the  direction 
indicated. 

Although  the  time  at  my  disposal  has  not  permitted  me 
duly  to  develop  these  thoughts,  yet  for  the  last  twelve 
months  the  subject  has  presented  itself  to  me  almost  daily 
under  one  aspect  or  another.  I  have  never  eaten  a  biscuit 
during  this  period  without  remarking  the  cleavage 
developed  by  the  rolling-pin.  You  have  only  to  break  a 
biscuit  across,  an-d  to  look  at  the  fracture,  to  see  the 
laminated  structure.  We  have  here  the  means  of  pushing 
the  analogy  further.  I  invite  you  to  compare  the  struc- 
ture of  the  slate,  which  was  subjected  to  a  high  tempera- 
ture during  the  conflagration  of  Mr. Scott  Russell's  premises, 
with  that  of  a  biscuit.  Air  or  vapor  within  the  slate  has 
caused  it  to  swell,  and  the  mechanical  structure  it  reveals 
is  precisely  that  of  a  biscuit.  During  these  inquiries  I 
have  received  much  instruction  in  the  manufacture  of 
puff-paste.  Here  is  some  such  paste  baked  under  my  own 
superintendence.  The  cleavage  of  our  hills  is  accidental 
cleavage,  but  this  is  cleavage  with  intention.  The  volition 
of  the  pastrycook  has  entered  into  its  formation.  It  has 
been  his  aim  to  preserve  a  series  of  surfaces  of  struc- 
tural weakness,  along  which  the  dough  divides  into  layers. 
Puff-paste  in  preparation  must  not  be  handled  too  much; 
it  ought,  moreover,  to  be  rolled  on  a  cold  slab,  to 
prevent  the  butter  from  melting,  and  diffusing  itself,  thus 
rendering  the  paste  more  homogeneous  and  less  liable  to 
split.  Puff-paste  is,  then,  simply  an  exaggerated  case  of 
slaty  cleavage. 

The  principle  here  enunciated  is  so  simple  as  to  be 
almost  trivial;  nevertheless,  it  embraces  not  only  the  cases 
mentioned,  but,  if  time  permitted,  it  might  be  shown  you 
that  the  principle  has  a  much  wider  range  of  application. 
When  iron  is  taken  from  the  puddling  furnace  it  is  more 
or  less  spongy,  an  aggregate  in  fact  of  small  nodules:  it  is 
at  a  welding  heat,  and  at  this  temperature  is  submitted  to 
the  process  of  rolling.  Bright  smooth  bars  are  the  result. 
But  notwithstanding  the  high  heat  the  nodules  do  not 


ON  CR Y8TAL LINE  AND  SLA  TY  CL  EA  VA GE.      243 

perfectly  blend  together.  The  process  of  rolling  draws 
them  into  fibers.  Here  is  a  mass  acted  upon  by  dilute 
sulphuric  acid,  which  exhibits  in  a  striking  manner  this 
fibrous  structure.  The  experiment  was  made  by  my 
friend  Dr.  Percy,  without  any  reference  to  the  question  of 
cleavage. 

Break  a  piece  of  ordinary  iron  and  you  have  a  granular 
fracture;  beat  the  iron,  you  elongate  these  granules,  and 
finally  render  the  mass  fibrous.  Here  are  pieces  of  rails 
along  which  the  wheels  of  locomotives  have  slidden;  the 
granules  have  yielded  and  become  plates.  They  exfoliate 
or  come  off  in  leaves;  all  these  effects  belong,  I  believe,  to 
the  great  class  of  phenomena  of  which  slaty  cleavage  forms 
the  most  prominent  example.* 

We  have  now  reached  the  termination  of  our  task.  You 
have  witnessed  the  phenomena  of  crystallization,  and  have 
had  placed  before  you  the  facts  which  are  found  associated 
with  the  cleavage  of  slate  rocks.  Such  facts,  as  expressed 
by  Helmholtz,  are  so  many  telescopes  to  our  spiritual 
vision,  by  which  we  can  see  backward  through  the  night 
of  antiquity,  and  discern  the  forces  which  have  been  in 
operation  upon  the  earth's  surface 

Ere  the  lion  roared, 
Or  the  eagle  soared. 

From  evidence  of  the  most  independent  and  trustworthy 
character,  we  come  to  the  conclusion  that  these  slaty  masses 
have  been  subjected  to  enormous  pressure,  and  by  the  sure 
method  of  experiment  we  have  shown — and  this  is  the  only 
really  new  point  which  has  been  brought  before  you — how 
the  pressure  is  sufficient  to  produce  the  cleavage.  Expand- 
ing our  field  of  view,  we  find  the  selfsame  law,  whose  foot- 
steps we  trace  amid  the  crags  of  Wales  and  Cumberland, 
extending  into  the  domain  of  the  pastrycook  and  iron- 
founder;  nay,  a  wheel  cannot  roll  over  the  half-dried  mud 
of  our  streets  without  revealing  to  us  more  or  less  of  the 
features  of  this  law.  Let  me  say,  in  conclusion,  that  the 
spirit  in  which  this  problem  has  been  attacked  by  geologists, 
indicates  the  dawning  of  a  new  day  for  their  science.  The 
great  intellects  who  have  labored  at  geology,  and  who  have 
raised  it  to  its  present  pitch  of  grandeur,  were  compelled  to 

*For  some  further  observations  on  this  subject  by  Mr.  Sorby  and 
myself,  see  Philosophical  Magazine  for  August,  1856. 


244  FRAGMENTS  OP  SCIENCE. 

deal  with  the  "subject  in  mass;  they  had  no  time  to  look 
after  details.  But  the  desire  for  more  exact  knowledge  is 
increasing;  facts  are  flowing  in  which,  while  they  leave 
untouched  the  intrinsic  wonders  of  geology,  are  gradually 
supplanting  by  solid  truths  the  uncertain  speculations 
which  beset  the  subject  in  its  infancy.  Geologists  now 
aim  to  imitate,  as  far  as  possible,  the  conditions  of  nature, 
and  to  produce  her  results;  they  are  approaching  more  and 
more  to  the  domain  of  physics,  and  I  trust  the  day  will 
soon  come  when  we  shall  interlace  our  friendly  arms  across 
the  common  boundary  of  our  sciences,  and  pursue  our 
respective  tasks  in  a  spirit  of  mutual  helpfulness,  encourage- 
ment and  goodwill. 

[I  would  now  lay  more  stress  on  the  lateral  yielding, 
referred  to  in  the  note  at  the  bottom  of  page  241,  accom- 
panied as  it  is  by  tangential  sliding,  than  I  was  prepared  to 
do  when  this  lecture  was  given.  This  sliding  is,  I  think, 
the  principal  cause  of  the  planes  of  weakness,  both  in 
pressed  wax  and  slate  rock.  J.  T.  1871.] 


CHAPTER  XIII. 

ON  PARAMAGNETIC    AND    DIAMAGNETIC    FORCES.* 

THE  NOTION  of  an  attractive  force,  which  draws  bodies 
toward  the  center  of  the  earth,  was  entertained  by  Anax- 
agoras  and  his  pupils,  by  Democritus,  Pythagoras,  and 
Epicurus;  and  the  conjectures  of  these  ancients  were 
renewed  by  Galileo,  Huyghens,  and  others,  who  stated 
that  bodies  attract  each  other  as  a  magnet  attracts  iron. 
Kepler  applied  the  notion  to  bodies  beyond  the  surface  of 
the  earth,  and  affirmed  the  extension  of  this  force  to  the 
most  distant  stars.  Thus  it  would  appear,  that  in  the 
attraction  of  iron  by  a  magnet  originated  the  conception  of 
the  force  of  gravitation.  Nevertheless,  if  we  look  closely 
at  the  matter,  it  will  be  seen  that  the  magnetic  force 

Eossesses  characters  strikingly  distinct  from  those  of  the 
:>rce  which  holds  the  universe   together.     The  theory   of 
gravitation   is,    that    every    particle    of    matter    attracts 

*  Abstract  of  a  discourse  delivered  in  the  Royal  Institution, 
February  1,  1856. 


PARAMAGNETIC  AND  DIAM'AONETIC  FORCES.  245 

every  other  particle;  in  magnetism  also  we  have  attraction, 
but  we  have  always,  at  the  same  time,  repulsion,  the  final 
effect  being  due  to  the  difference  of  these  two  forces.  A 
body  may  be  intensely  acted  on  by  a  magnet,  and  still  no 
motion  of  translation  will  follow,  if  the  repulsion  be  equal 
to  the  attraction.  Previous  to  magnetization,  a  dipping 
needle,  when  its  center  of  gravity  is  supported,  stands 
accurately  level;  but,  after  magnetization,  one  end  of  it, 
in  our  latitude,  is  pulled  toward  the  north  pole  of  the 
earth.  The  needle,  however,  being  suspended  from  the 
arm  of  a  fine  balance,  its  weight  is  found  unaltered  by  its 
magnetization.  In  like  manner,  when  the  needle  is  per- 
mitted to  float  upon  a  liquid,  and  thus  to  follow  the  attrac- 
tion of  the  north  magnetic  pole  of  the  earth,  there  is  no 
motion  of  the  mass  toward  that  pole.  The  reason  is  known 
to  be,  that  although  the  marked  end  of  the  needle  is 
attracted  by  the  north  pole,  the  unmarked  end  is  repelled 
by  an  equal  force,  the  two  equal  and  opposite  forces 
neutralizing  each  other. 

When  the  pole  of  an  ordinary  magnet  is  brought  to  act 
upon  the  swimming  needle,  the  latter  is  attracted — the 
reason  being  that  the  attracted  end  of  the  needle  being 
nearer  to  the  pole  of  the  magnet  than  the  repelled 
end,  the  force  of  attraction  is  the  more  powerful  of 
the  two.  In  the  case  of  the  earth,  its  pole  is  so 
distant  that  the  length  of  the  needle  is  practically  zero. 
In  like  manner,  when  a  piece  of  iron  is  presented  to  a 
magnet,  the  nearer  parts  are  attracted,  while  the  more  dis- 
tant parts  are  repelled;  and  because  the  attracted  portions 
are  nearer  to  the  magnet  than  the  repelled  ones,  we  have  a 
balance  in  favor  of  attraction.  Here,  then,  is  the  special 
characteristic  of  the  magnetic  force,  which  distinguishes  it 
from  that  of  gravitation.  The  latter  is  a  simple  uupolar 
force,  while  the  former  is  duplex  or  polar.  Were  gravita- 
tion like  magnetism,  a  stone  would  no  more  fall  to  the 
ground  than  a  piece  of  iron  toward  the  north  magnetic 
pole:  and  thus,  however  rich  in  consequences  the  supposi- 
tion of  Kepler  and  others  may  have  been,  it  is  clear  that  a 
force  like  that  of  magnetism  would  not  be  able  to  trans- 
act the  business  of  the  universe. 

The  object  of  this  discourse  is  to  inquire  whether 
the  force  of  diamagnetism,  which  manifests  itself  as  a 
repulsion  of  certain  bodies  by  the  poles  of  a  magnet,  is  to 


246  FRAGMENTS  OF  SCIENCE. 

be  ranged  as  a  polar  force,  beside  that  of  magnetism;  or  as 
an  unpolar  force  beside  that  of  gravitation.  When  a 
cylinder  of  soft  iron  is  placed  within  a  wire  helix,  and  sur- 
rounded by  an  electric  current,  the  antithesis  of  its  two 
ends,  or,  in  other  words,  its  polar  excitation,  is  at  once 
manifested  by  its  action  upon  a  magnetic  needle;  and  it 
may  be  asked  why  a  cylinder  of  bismuth  may  not  be  sub- 
stituted for  the  cylinder  of  iron,  and  its  state  similarly  ex- 
amined. The  reason  is,  that  the  excitement  of  the  bismuth 
is  so  feeble,  that  it  would  be  quite  masked  by  that  of  the 
helix  in  which  it  is  enclosed;  and  the  problem  that  now 
meets  us  is,  so  to  excite  a  diamagnetic  body  that  the  pure 
action  of  the  body  upon  a  magnetic  needle  may  be  observed, 
unmixed  with  the  action  of  the  body  used  to  excite  the 
diamagnetic. 

How  this  has  been  effected  may  be  illustrated  in  the 
following  manner:  When  through  an  upright  helix  of 
covered  copper  wire,  a  voltaic  current  is  sent,  the  top  of 
the  helix  attracts,  while  its  bottom  repels,  the  same  pole 


FIG.  10. 

of  a  magnetic  needle;  its  central  point,  on  the  contrary,  is 
neutral,  and  exhibits  neither  attraction  nor  repulsion. 
Such  a  helix  is  caused  to  stand  between  the  two  poles  N"  s' 
of  an  astatic  system.*  The  two  magnets  s  N'  arid  s'  N"  are 
united  by  a  rigid  cross  piece  at  their  centers,  and  are  sus- 
pended from  the  point  a,  so  that  both  magnets  swing  in 
the  same  horizontal  plane.  It  is  so  arranged  that  the  poles 
N' s' are  opposite  to  the  central  or  neutral  point  of  the 
helix,  so  that  when  a  current  is  sent  through  the  latter,  the 
magnets,  as  before  explained,  are  unaffected.  Here,  then, 
we  have  an  excited  helix  which  itself  has  no  action  upon 
the  magnets,  and  we  are  thus  enabled  to  examine  the 
action  of  a  body  placed  within  the  helix  and  excited  by  it, 

*  The  reversal  of  the  poles  of  the  two  magnets,  which  were  of  the 
same  strength,  completely  annulled  the  action  of  the  earth  as  a 
magnet. 


PARAMAGNETIC  AND  DIAMAQNETIC  FORCES.  247 

undisturbed  «by  the  influence  of  the  latter.  The  helix 
being  12  inches  high,  a  cylinder  of  soft  iron  6  inches  long, 
suspended  from  a  string  and  passing  over  a  pulley,  can  be 
raised  or  lowered  within  the  helix.  When  it  is  so  far  sunk 
that  its  lower  end  rests  upon  the  table,  the  upper  end 
finds  itself  between  the  poles  N'  s'  of  the  astatic  system. 
The  iron  cylinder  is  thus  converted  into  a  strong  magnet, 
attracting  one  of  the  poles,  and  repelling  the  other,  and 
consequently  deflecting  the  entire  astatic  system.  When 
the  cylinder  is  raised  so  that  the  upper  end  is  at  the  level 
of  the  top  of  the  helix,  its  lower  end  conies  between  the 
poles  N'  s';  and  a  deflection  opposed  in  direction  to  the 
former  one  is  the  immediate  consequence.  To  render 
these  deflections  more  easily  visible,  a  mirror  m  is  attached 
to  the  system  of  magnets.;  a  beam  of  light  thrown  upon  the 
mirror  being  reflected  and  projected  as  a  bright  disk 
against  the  wall.  The  distance  of  this  image  from  the 
mirror  being  considerable,  and  its  angular  motion  double 
that  of  the  latter,  a  very  slight  motion  of  the  magnet  is 
sufficient  to  produce  a  displacement  of  the  image  through 
several  yards. 

This,  then,  is  the  principle  of  the  beautiful  apparatus*  by 
which  the  investigation  was  conducted.  It  is  manifest 
that  if  a  second  helix  be  placed  between  the  poles  SN  with 
a  cylinder  within  it,  the  action  upon  the  astatic  magnet 
may  be  exalted.  This  was  the  arrangement  made  use  of 
in  the  actual  inquiry.  Thus  to  intensify  the  feeble  action, 
which  it  is  here  our  object  to  seek,  we  have  in  the  first 
place  neutralized  the  action  of  the  earth  upon  the  magnets, 
by  placing  them  astatically.  Secondly,  by  making  use  of 
two  cylinders,  and  permitting  them  to  act  simultaneously 
on  the  four  poles  of  the  magnets,  we  have  rendered  the 
deflecting  force  four  times  what  it  would  be,  if  only  a 
single  pole  were  used.  Finally  the  whole  apparatus  was 
enclosed  in  a  suitable  case  which  protected  the  magnets 
from  air-currents,  and  the  deflections  were  read  off 
through  a  glass  plate  in  the  case,  by  means  of  a  telescope 
and  scale  placed  at  a  considerable  distance  from  the  instru- 
ment. 

A  pair  of  bismuth  cylinders  was  first  examined.    Sending 

*  Devised  by  Prof.  W.  Weber,  and  constructed  by  M.  Leyser,  of 
Leipsic. 


248  FRAGMENTS  OF  SCIENCE. 

a  current  through  the  helices,  aud  observing  that  the 
magnets  swung  perfectly  free,  it  was  first  arranged  that  the 
bismuth  cylinders  within  the  helices  had  their  central  or 
neutral  points  opposite  to  the  poles  of  the  magnets.  All 
being  at  rest  the  number  on  the  scale  marked  by  the  cross 
wire  of  the  telescope  was  572.  The  cylinders  were  then 
moved,  one  up,  the  other  down,  so  that  two  of  their  ends 
were  brought  to  bear  simultaneously  upon  the  magnetic 
poles:  the  magnet  moved  promptly,  and  after  some  oscil- 
lations* came  to  rest  at  the  number  612;  thus  moving 
from  a  smaller  to  a  larger  number.  The  other  two  ends  of 
the  bars  were  next  brought  to  bear  upon  the  magnet:  a 
prompt  deflection  was  the  consequence,  and  the  final 
position  of  equilibrium  was  526:  the  movement  being 
from  a  larger  to  a  smaller  number.  We  thus  observe 
a  manifest  polar  action  of  the  bismuth  cylinders  upon 
the  magnet;  one  pair  of  ends  deflecting  it  in  one  direc- 
tion, and  the  other  pair  deflecting  it  in  the  opposite 
direction. 

Substituting  for  the  cylinders  of  bismuth  thin  cylinders 
of  iron,  of  magnetic  slate,  of  sulphate  of  iron,  carbonate  of 
iron,  protochloride  of  iron,  red  ferrocyanide  of  potassium, 
and  other  magnetic  bodies,  it  was  found  that  when  the 
position  of  the  magnetic  cylinders  was  the  same  as  that  of 
the  cylinders  of  bismuth,  the  deflection  produced  by  the 
former  was  always  opposed  in  direction  to  that  produced  by 
the  latter;  and  hence  the  disposition  of  the  force  in  the 
diamagnetic  body  must  have  been  precisely  antithetical  to 
its  disposition  in  the  magnetic  ones. 

But  it  will  be  urged,  and  indeed  has  been  urged  against 
this  inference,  that  the  deflection  produced  by  the  bismuth 
cylinders  may  be  due  to  induced  currents  excited  in  the 
metal  by  its  motion  within  the  helices.  In  reply  to  this 
objection,  it  may  be  stated,  in  the  first  place,  that  the  deflec- 
tion is  permanent,  and  cannot  therefore  be  due  to  induced 
currents,  which  are  only  of  momentary  duration.  It  has 
also  been  urged  that  such  experiments  ought  to  be  made 
with  other  metals,  and  with  better  conductors  than  bismuth; 
for  if  due  to  currents  of  induction,  the  better  the  conductor 
the  more  exalted  will  be  the  effect.  This  requirement  was 
complied  with. 

*  To  lessen  these  a  copper  damper  was  made  use  of. 


PARAMAGNETIC  AND  DIAMAGNETIG  FORCES.     24.9 

Cylinders  of  antimony  were  substituted  for  those  of  bis- 
muth. This  metal  is  a  better  conductor  of  electricity,  but 
less  strongly  diamugnetic  than  bismuth.  If  therefore  the 
action  referred  to  be  due  to  induced  currents  we  ought  to 
have  it  greater  in  the  case  of  antimony  than  with  bismuth; 
but  if  it  springs  from  a  true  diamaguetic  polarity,  the  action 
of  the  bismuth  ought  to  exceed  that  of  the  antimony.  Ex- 
periment proves  this  to  be  the  case.  Hence  the  deflection 
produced  by  these  metals  is  due  to  their  diamagnetic,  and 
not  to  their  conductive  capacity.  Copper  cylinders  were 
next  examined:  here  we  have  a  metal  which  conducts  elec- 
tricity fifty  times  better  than  bismuth,  but  its  diamagnetic 
power  is  nearly  null;  if  the  effects  be  due  to  induced  cur- 
rents we  ought  to  have  them  here  in  an  enormously  exag- 
gerated degree,  but  no  sensible  deflection  was  produced  by 
the  two  cylinders  of  copper. 

It  has  also  been  proposed  by  the  opponents  of  diamagnetic 
polarity  to  coat  fragments  of  bismuth  with  some  insulating 
substance,  so  as  to  render  the  formation  of  induced  cur- 
rents impossible,  and  to  test  the  question  with  cylinders 
of  these  fragments.  This  requirement  was  also  fulfilled. 
It  is  only  necessary  to  reduce  the  bismuth  to  powder  and 
expose  it  for  a  short  time  to  the  air  to  cause  the  particles 
to  become  so  far  oxidized  as  to  render  them  perfectly 
insulating.  The  insulating  power  of  the  powder  was 
exhibited  experimentally;  nevertheless,  this  powder, 
enclosed  in  glass  tubes,  exhibited  an  action  scarcely  less 
powerful  than  that  of  the  massive  bismuth  cylinders. 

But  the  most  rigid  proof,  a  proof  admitted  to  be  con- 
clusive by  those  who  have  denied  the  antithesis  of  magnet- 
ism and  diamagnetism,  remains  to  be  stated.  Prisms  of 
the  same  heavy  glass  as  that  with  which  the  diamagnetic 
force  was  discovered,  were  substituted  for  the  metallic 
cylinders,  and  their  action  upon  the  magnet  was  proved 
to  be  precisely  the  same  in  kind  as  that  of  the  cylinders  of 
bismuth.  The  inquiry  was  also  extended  to  other 
insulators:  to  phosphorus,  sulphur,  niter,  calcareous  spar, 
statuary  marble,  with  the  same  invariable  result:  each  of 
these  substances  was  proved  to  be  polar,  the  disposition  of 
the  force  being  the  same  as  that  of  bismuth  and  the 
reverse  of  that  of  iron.  When  a  bar  of  iron  is  set  erect,  its 
lower  end  is  known  to  be  a  north  pole,  and  its  upper  end 
a  south  pole,  in  virtue  of  the  earth's  induction.  A  nwblo 


250  FRAGMENTS  OF  SCIENCE. 

statue,  on  the  contrary,  has  its  feet  a  south  pole,  and  its 
head  a  north  pole,  and  there  is  no  doubt  that  the  same 
remark  applies  to  its  living  archetype;  each  man  walking 
over  the  earth's  surface  is  a  true  diamagnet,  with  its  poles 
the  reverse  of  those  of  a  mass  of  magnetic  matter  of  the 
same  shape  and  position. 

An  experiment  of  practical  value,  as  affording  a  ready 
estimate  of  the  different  conductive  powers  of  two  metals 
for  electricity,  was  exhibited  in  the  lecture,  for  the  purpose 
of  proving  experimentally  some  of  the  statements  made  in 
reference  to  this  subject.  A  cube  of  bismuth  was  suspended 
by  a  twisted  string  between  the  two  poles  of  an  electro- 
magnet. The  cube  was  attached  by  a  short  copper  wire  to 
a  little  square  pyramid,  the  base  of  which  was  horizontal, 
and  its  sides  formed  of  four  small  triangular  pieces  of 
looking-glass.  A  beam  of  light  was  suffered  to  fall  upon 
this  reflector,  and  as  the  reflector  followed  the  motion  of 
the  cube  the  images  cast  from  its  sides  followed  each 
other  in  succession,  each  describing  a  circle  about  thirty 
feet  in  diameter.  As  the  velocity  of  rotation  augmented, 
these  images  blended  into  a  continuous  ring  of  light.  At 
a  particular  instant  the  electro-magnet  was  excited,  cur- 
rents were  evolved  in  the  rotating  cube,  and  the  strength 
of  these  currents,  which  increases  with  the  conductivity  of 
the  cube  for  electricity,  was  practically  estimated  by  the 
time  required  to  bring  the  cube  and  its  associated  mirrors 
to  a  state  of  rest.  With  bismuth  this  time  amounted  to  a 
score  of  seconds  or  more:  a  cube  of  copper,  on  the  contrary, 
was  struck  almost  instantly  motionless  when  the  circuit 
was  established. 


CHAPTER  XIV. 

PHYSICAL  BASIS   OF   SOLAR   CHEMISTKY.* 

OMITTING  all  preface,  attention  was  first  drawn  to  an 
experimental  arrangement  intended  to  prove  that  gaseous 
bodies  radiate  heat  in  different  degrees.  Near  a  double 
screen  of  polished  tin*  was  placed  an  ordinary  ring  gas- 
burner,  and  on  this  was  placed  a  hot  copper  ball,  from 

*  From  a  discourse  delivered  at  the  Royal  Institution  of  Great 
Britain,  June  7,  1861. 


PHYSICAL  BASIS  OF  SOLAR  CHEMISTRY.        £51 

which  a  column  of  heated  air  ascended.  Behind  the 
screen,  but  so  situated  that  no  ray  from  the  ball  could 
reach  the  instrument,  was  an  excellent  thermo-electric  pile, 
connected  by  wires  with  a  very  delicate  galvanometer. 
The  pile  was  known  to  be  an  instrument  whereby  heat  is 
applied  to  the  generation  of  electric  currents;  the  strength 
of  the  current  being  an  accurate  measure  of  the  quantity 
of  the  heat.  As  long  as  both  faces  of  the  pile  are  at  the 
same  temperature,  no  current  is  produced;  but  the 
slightest  difference  in  the  temperature  of  the  two  faces  at 
once  declares  itself  by  the  production  of  a  current,  which, 
when  carried  through  the  galvanometer,  indicates  by  the 
deflection  of  the  needle  both  its  strength  and  its 
direction. 

The  two  faces  of  the  pile  were  in  the  first  instance 
brought  to  the  same  temperature;  the  equilibrium  being 
shown  by  the  needle  of  the  galvanometer  standing  at  zero. 
The  rays  emitted  by  the  current  of  hot  air  already  referred 
to  were  permitted  to  fall  upon  one  of  the  faces  of  the  pile; 
and  an  extremely  slight  movement  of  the  needle  showed 
that  the  radiation  from  the  hot  air,  though  sensible,  was 
extremely  feeble.  Connected  with  the  ring-burner  was  a 
holder  containing  oxygen  gas;  and  by  turning  a  cock,  a 
stream  of  this  gas  was  permitted  to  issue  from  the  burner, 
strike  the  copper  ball,  and  ascend  in  a  heated  column  in 
front  of  the  pile.  The  result  was,  that  oxygen  showed 
itself,  as  a  radiator  of  heat,  to  be  quite  as  feeble  as 
atmospheric  air. 

A  second  holder  containing  olefiant  gas  was  then 
connected  with  the  ring-burner.  Oxygen  and  air  had 
already  flowed  over  the  ball  and  cooled  it  in  some  degree. 
Hence  the  olefiant  gas  labored  under  a  disadvantage.  But 
on  permitting  the  gas  to  rise  from  the  ball,  it  casts  an 
amount  of  heat  against  the  adjacent  face  of  the  pile 
sufficient  to  impel  the  needle  of  the  galvanometer  almost 
to  ninety  degrees.  This  experiment  proved  the  vast  dif- 
ference between  two  equally  invisible  gases  with  regard  to 
their  power  of  emitting  radiant  heat. 

The  converse  experiment  was  now  performed.  The 
thermo-electric  pile  was  removed  and  placed  between  two 
cubes  filled  witli  water  kept  in  a  state  of  constant  ebulli- 
tion; and  it  was  so  arranged  that  the  quantities  of  heat 
falling  from  the  cubes  on  the  opposite  faces  of  the  pile 


252  FRAGMENTS  OF  SCIENCE. 

were  exactly  equal,  thus  neutralizing  each  other.  The 
needle  of  the  galvanometer  being  at  zero,  a  sheet  of  oxygen 
gas  was  caused  to  issue  from  a  slit  between  one  of  the 
cubes  and  the  adjacent  face  of  the  pile.  If  this  sheet  of 
gas  possessed  any  sensible  power  of  intercepting  the 
thermal  rays  from  the  cube,  one  face  of  the  pile  being  de- 
prived of  the  heat  thus  intercepted,  a  difference  of  tempera- 
ture between  its  two  faces  would  instantly  set  in,  and  the 
result  would  be  declared  by  the  galvanometer.  The 
quantity  absorbed  by  the  oxygen  under  those  circum- 
stances was  too  feeble  to  affect  the  galvanometer;  the  gas, 
in  fact,  proved  perfectly  transparent  to  the  rays  of  heat. 
It  had  but  a  feeble  power  of  radiation-:  it  had  an  equally 
feeble  power  of  absorption. 

The  pile  remaining  in  its  position,  a  sheet  of  olefiant 
gas  was  caused  to  issue  from  the  same  slit  as  that  through 
which  the  oxygen  had  passed.  No  one  present  could  see 
the  gas;  it  was  quite  invisible,  the  light  went  through  it 
as  freely  as  through  oxygen  or  air;  but  its  effect  upon  the 
thermal  rays  emanating  from  the  cube  was  what  might  be 
expected  from  a  sheet  of  metal.  A  quantity  so  large  was 
cut  off,  that  the  needle  of  the  galvanometer,  promptly 
quitting  the  zero  line,  moved  with  energy  to  its  stops. 
Thus  the  olefiant  gas,  so  light  and  clear  and  pervious  to 
luminous  rays,  was  proved  to  be  a  most  potent  destroyer  of 
the  rays  emanating  from  an  obscure  source.  The  reciprocity 
of  action  established  in  the  case  of  oxygen  comes  out  here; 
the  good  radiator  is  found  by  this  experiment  to  be  the 
good  absorber. 

This  result,  now  exhibited  before  a  public  audience  for 
the  first  time,  was  typical  of  what  had  been  obtained  with 
gases  generally.  Going  through  the  entire  list  of  gases 
and  vapors  in  this  way,  we  find  radiation  and  absorption 
to  be  as  rigidly  associated  as  positive  and  negative  in  elec- 
tricity, or  as  north  and  south  polarity  in  magnetism.  So 
that  if  we  make  the  number  which  expresses  the  absorptive 
power  the  numerator  of  a  fraction,  and  that  which  expresses 
its  radiative  power  the  denominator,  the  result  would  be, 
that  on  account  of  the  numerator  and  denominator  varying 
in  the  same  proportion,  the  value  of  that  fraction  would 
always  remain  the  same,  whatever  might  be  the  gas  or 
vapor  experimented  with". 

But  why  should  this  reciprocity  exist?    What  is  the 


PHYSICAL  BASIS  OF  SOLAR  CHEMISTRY        253 

meaning  of  absorption?  what  is  the  meaning  of  radiation? 
When  you  cast  a  stone  into  still  water,  rings  of  waves  sur- 
round the  place  where  it  falls;  motion  is  radiated  on  all 
sides  from  the  center  of  disturbance.  When  a  hammer 
strikes  a  bell,  the  latter  vibrates;  and  sound  which  is  noth- 
ing more  than  an  undulatory  motion  of  the  air,  is  radiated 
in  all  directions.  Modern  philosophy  reduces  light  and 
heat  to  the  same  mechanical  category.  A  luminous  body 
is  one  with  its  atoms  in  a  state  of  vibration;  a  hot  body  is 
one  with  its  atoms  also  vibrating,  but  at  a  rate  which  is 
incompetent  to  excite  the  sense  of  vision;  and,  as  a  sound- 
ing body  has  the  air  around  it,  through  which  it  propagates 
its  vibrations,  so  also  the  luminous  or  heated  body  has  a 
medium,  called  ether,  which  accepts  its  motions  and 
carries  them  forward  with  inconceivable  velocity.  Kadia- 
tion,  then,  as  regards  both  light  and  heat,  is  the  transference 
of  motion  from  the  vibrating  body  to  the  ether  in  which  it 
swings:  and,  as  in  the  case  of  sound,  the  motion  imparted 
to  the  air  is  soon  transferred  to  surrounding  objects,  against 
which  the  aerial  undulations  strike,  the  sound  being  in 
technical  language,  absorbed;  so  also  with  regard  to  light 
and  heat,  absorption  consists  in  the  transference  of  motion 
from  the  agitated  ether  to  the  molecules  of  the  absorbing 
body. 

The  simple  atoms  are  found  to  be  bad  radiators;  the 
compound  atoms  good  ones:  and  the  higher  the  degree  of 
complexity  in  the  atomic  grouping,  the  more  potent,  as  a 
general  rule,  is  the  radiation  and  absorption.  Let  us  get 
definite  ideas  here,  however  gross,  and  purify  them  after- 
ward by  the  process  of  abstraction.  Imagine  our  simple 
atoms  swinging  like  single  spheres  in  the  ether;  they  can- 
not create  the  swell  which  a  group  of  them  united  to  form 
a  system  can  produce.  An  oar  runs  freely  edgeways  through 
the  water,  and  imparts  far  less  of  its  motion  to  the  water 
than  when  its  broad  flat  side  is  brought  to  bear  upon  it. 
In  our  present  language  the  oar,  broad  side  vertical,  is  a 
good  radiator;  broad  side  horizontal,  it  is  a  bad  radiator. 
Conversely  the  waves  of  water,  impinging  upon  the  flat 
face  of  the  oar-blade,  will  impart  a  greater  amount  of  mo- 
tion to  it  than  when  impinging  upon  the  edge.  In  the 
position  in  which  the  oar  radiates  well,  it  also  absorbs 
well.  Simple  atoms  glide  through  the  ether  without  much 
resistance;  compound  ones  encounter  resistance,  and  hence 


254  FRAGMENTS  OF  SCIENCE. 

yield  up  more  speedily  their  motion  to  the  ether.  Mix 
oxygen  and  nitrogen  mechanically,  they  absorb  and  radiate 
a  certain  amount  of  heat.  Cause  tbese  gases  to  combine 
chemically  and  form  nitrous  oxide,  both  the  absorption  and 
radiation  are  thereby  augmented  hundreds  of  times! 

lu  this  way  we  look  with  the  telescope  of  the  intellect 
into  atomic  systems,  and  obtain  a  conception  of  processes 
which  the  eye  of  sense  can  never  reach.  But  gases  and 
vapors  possess  a  power  of  choice  as  to  the  rays  which  they 
absorb.  They  single  out  certain  groups  of  rays  for  de- 
struction, and  allow  other  groups  to  pass  unharmed.  This 
is  best  illustrated  by  a  famous  experiment  of  Sir  David 
Brewster's,  modified  to  suit  present  requirements.  Into  a 
glass  cylinder,  with  its  ends  stopped  by  disks  of  plate-glass, 
a  small  quantity  of  nitrous  acid  gas  is  introduced,  the 
presence  of  the  gas  being  indicated  by  its  rich  brown  color. 
The  beam  from  an  electric  lamp  being  sent  through  two 
prisms  of  bisulphide  of  carbon,  a  spectrum  seven  feet  long 
and  eighteen  inches  wide  is  cast  upon  the  screen.  Intro- 
ducing the  cylinder  containing  the  nitrous  acid  into  the 
path  of  the  beam  as  it  issues  from  the  lamp,  the  splendid 
and  continuous  spectrum  becomes  instantly  furrowed  by 
numerous  dark  bands,  the  rays  answering  to  which  are 
intercepted  by  the  nitric  gas,"  while  the  light  which  falls 
upon  the  intervening  spaces  is  permitted  to  pass  with  com- 
parative impunity. 

Here  also  the  principle  of  reciprocity,  as  regards  radia- 
tion and  absorption,  holds  good;  and  could  we,  without 
otherwise  altering  its  physical  character,  render  that 
nitrous  gas  luminous,  we  should  find  that  the  very  rays 
which  it  absorbs  are  precisely  those  which  it  would  emit. 
When  atmospheric  air  and  other  gases  are  brought  to  a 
state  of  intense  incandescence  by  the  passage  of  an  electric 
spark,  the  spectra  which  we  obtain  from  them  consist  of  a 
series  of  bright  bands.  But  such  spectra  are  produced 
with  the  greatest  brilliancy  when,  instead  of  ordinary  gases, 
we  make  use  of  metals  heated  so  highly  as  to  volatilize 
them.  This  is  easily  done  by  the  voltaic  current.  A  cap- 
sule of  carbon  filled  with  mercury,  which  formed  the 
positive  electrode  of  the  electric  lamp,  has  a  carbon  point 
brought  down  upon  it.  On  separating  the  one  from  the 
other,  a  brilliant  arc  containing  the  mercury  in  a  volatil- 
ized condition  passes  between  them.  The  spectrum  of  this 


PHYSICAL  BASIS  OF  SOLAR  CHKMTSTRT.        255 

arc  is  not  continuous  like  that  of  the  solid  carbon  points, 
but  consists  of  a  series  of  vivid  bands,  each  corresponding 
in  color  to  that  particular  portion  of  the  spectrum  to  which 
its  rays  belong.  Copper  gives  its  system  of  bands;  zinc 
gives  its  system;  and  brass,  which  is  an  alloy  of  copper  and 
zinc,  gives  a  spectrum  made  up  of  the  bands  belonging  to 
both  metals. 

Not  only,  however,  when  metals  are  united  like  zinc 
and  copper  to  form  an  alloy,  is  it  possible  to  obtain  the 
bands  which  belong  to  them.  No  matter  how  we  may 
disguise  the  metal — allowing  it  to  unite  with  oxygen  to 
form  an  oxide,  and  this  again  with  an  acid  to  form  a  salt; 
if  the  heat  applied  be  sufficiently  intense,  the  bands  be- 
longing to  the  metal  reveal  themselves  with  perfect  defi- 
nition. Into  holes  drilled  in  a  cylinder  of  retort  carbon, 
pure  culinary  salt  is  introduced.  When  the  carbon  is 
made  the  positive  electrode  of  the  lamp,  the  resultant 
spectrum  shows  the  brilliant  yellow  lines  of  the  metal 
sodium.  Similar  experiments  made  with  the  chlorides  of 
strontium,  calcium,  lithium,*  and  other  metals,  give  the 
bands  due  to  the  respective  metals.  When  different  salts 
are  mixed  together,  and  rammed  into  holes  in  the  carbon, 
a  spectrum  is  obtained  which  contains  the  bands  of 
them  all. 

The  position  of  these  bright  bands  never  varies,  and 
each  metal  has  its  own  system.  Hence  the  competent 
observer  can  infer  from  the  bauds  of  the  spectrum  the 
metals  which  produce  it.  It  is  a  language  addressed  to 
the  eye  instead  of  the  ear;  and  the  certainty  would  not  be 
augmented  if  each  metal  possessed  the  power  of  audibly 
calling  out,  "  I  am  here!"  Nor  is  this  language  affected 
by  distance.  If  we  find  that  the  sun  or  the  stars  give  us 
the  bands  of  our  terrestrial  metals,  it  is  a  declaration  on 
the  part  of  these  orbs  that  such  metals  enter  into  their  com- 
position. Does  the  sun  give  us  any  such  intimation? 
Does  the  solar  spectrum  exhibit  bright  lines  which  we 

*  The  vividness  of  the  colors  of  the  lithium  spectrum  is  extraor- 
dinary; the  spectrum,  moreover,  contained  a  blue  band  of  indescrib- 
able splendor.  It  was  thought  by  many,  during  the  discourse,  that  I 
had  mistaken  strontium  for  lithium,  as  this  blue  band  had  never 
before  been  seen.  I  have  obtained  it  many  times  since;  and  my 
friend  Dr.  Miller,  having  kindly  analyzed  the  substance  made  use  of, 
pronounces  it  pure  chloride  of  lithium. — J.  T. 


256  FRAGMENTS  OF  SCIENCE. 

might  compare  with  those  produced  by  our  terrestrial 
metals,  and  prove  either  their  identity  or  difference?  No. 
The  solar  spectrum,  when  closely  examined,  gives  us  a 
multitude  of  fine  dark  lines  instead  of  bright  ones.  They 
were  first  noticed  by  Dr.  Wollaston,  but  were  multiplied 
and  investigated  with  profound  skill  by  Fraunhofer,  and 
named  after  him  Fraunhofer's  lines.  They  had  been  long 
a  standing  puzzle  to  philosophers.  The  bright  lines 
yielded  by  metallic  vapors  had  been  also  known  to  us  for 
years;  but  the  connection  between  both  classes  of  phenom- 
ena was  wholly  unknown,  until  Kirchhoff,  with  admi- 
rable acuteness,  revealed  the  secret,  and  placed  it  at  the 
same  time  in  our  power  to  chemically  analyze  the  sun. 

We  have  now  some  difficult  work  before  us.  Hitherto 
we  have  been  delighted  by  objects  which  addressed  them- 
selves as  much  to  our  sesthetic  taste  as  to  our  scientific 
faculty;  we  have  ridden  pleasantly  to  the  base  of  the  final 
cone  o"f  Etna,  and  must  now  dismount  and  march  through 
ashes  and  lava,  if  we  would  enjoy  the  prospect  from  the 
summit.  Our  problem  is  to  connect  the  dark  lines  of 
Fraunhofer  with  the  bright  ones  of  the  metals.  The 
white  beam  of  the  lamp  is  refracted  in  passing  through  our 
two  prisms,  but  its  different  components  are  refracted  in 
different  degrees,  and  thus  its  colors  are  drawn  apart. 
Now  the  color  depends  solely  upon  the  rate  of  oscillation 
of  the  atoms  of  the  luminous  body;  red  light  being  pro- 
duced by  one  rate,  blue  light  by  a  much  quicker  rate,  and 
the  colors  between  red  and  blue  by  the  intermediate  rates. 
The  solid  incandescent  coal-points  give  us  a  continuous 
spectrum;  or  in  other  words  they  emit  rays  of  all  possible 
periods  between  the  two  extremes  of  the  spectrum.  Color, 
as  many  of  you  know,  is  to  light  what  pitch  is  to  sound. 
When  a  violin-player  presses  his  finger  on  a  string  he 
makes  it  shorter  and  tighter,  and  thus,  causing  it  to  vibrate 
more  speedily,  heightens  the  pitch.  Imagine  such  a  player 
to  move  his  fingers  slowly  along  the  string,  shortening  it 
gradually  as  he  draws  his  bow,  the  note  would  rise  in  pitch 
by  a  regular  gradation;  there  would  be  no  gap  intervening 
between  note  and  note.  Here  we  have  the  analogue  to 
the  continuous  spectrum,  whose  colors  insensibly  blend  to- 
gether without  gap  or  interruption,  from  the  red  of  the 
lowest  pitch  to  the  violet  of  the  highest.  But  suppose  the 
player,  instead  of  gradually  shortening  his  string,  to  press 


PHYSICAL  BASIS  OF  SOLAR  CHEMISTRY.        257 

his  finger  ou  a  certain  point,  anil  to  sound  the  correspond- 
ing note;  then  to  pass  on  to  another  point  more  or  less 
distant,  and  sound  its  note;  then  to  another,  and  so  on, 
thus  sounding  particular  notes  separated  from  each  other 
by  gaps  which  correspond  to  the  intervals  of  the  string 
passed  over;  we  should  then  have  the  exact  analogue  of  a 
spectrum  composed  of  separate  bright  bands  with  intervals 
of  darkness  between  them.  But  this,  though  a  perfectly 
true  and  intelligible  analogy,  is  not  sufficient  for  our  pur- 
pose; we  must  look  with  the  mind's  eye  at  the  oscillating 
atoms  of  the  volatilized  metal.  Figure  these  atoms  as  con- 
nected together  by  springs  of  a  certain  tension,  which,  if 
the  atoms  are  squeezed  together,  push  them  again  asunder, 
and  if  the  atoms  are  drawn  apart,  pull  them  again  together, 
causing  them,  before  coming  to  rest,  to  quiver  for  a  certain 
time  at  a  certain  definite  rate  determined  by  the  strength 
of  the  spring.  Now  the  volatilized  metal  which  gives  us 
one  bright  baud  is  to  be  figured  as  having  its  atoms  united 
by  springs  all  of  the  same  tension,  its  vibrations  are  all  of 
one  kind.  The  metal  which  gives  us  two  bands  may  be 
figured  as  having  some  of  its  atoms  united  by  springs  of  one 
tension,  and  others  by  springs  of  a  different  tension.  Its 
vibrations  are  of  two  distinct  kinds;  so  also  when  we  have 
three  or  more  bands  we  are  to  figure  as  many  distinct  sets 
of  springs,  each  capable  of  vibrating  in  its  own  particular 
time  and  at  a  different  rate  from  the  others.  If  we  seize 
this  idea  definitely,  we  shall  have  no  difficulty  in  dropping 
the  metaphor  of  springs,  and  substituting  for  it  mentally 
the  forces  by  which  the  atoms  act  upon  each  other. 
Having  thus  far  cleared  our  way,  let  us  make  another 
effort  to  advance. 

A  heavy  ivory  ball  is  here  suspended  from  a  string,  I 
blow  against  this  ball;  a  single  puff  of  my  breath  moves  it 
a  little  way  from  its  position  of  rest;  it  swings  back  toward 
me,  and  when  it  reaches  the  limit  of  its  swing  I  puff  again. 
It  now  swings  further;  and  thus  by  timing  the  puffs  I  can 
so  accumulate  their  action  as  to  produce  oscillations  of 
large  amplitude.  The  ivory  ball  here  has  absorbed  the 
motion  which  my  breath  communicated  to  the  air.  I  now 
bring  the  ball  to  rest.  Suppose,  instead  of  the  breath,  a 
wave  of  air  to  strike  against  it,  and  that  this  wave  is 
followed  by  a  series  of  others  which  succeed  each  other 
exactly  IE  the  same  intervals  as  my  puffs;  it  is  obvious  that 


g58  FRAGMENTS  OF  SCIENCE. 

these  waves  would  communicate  their  motion  to  the  ball 
and  cause  it  to  swing  as  the  puffs  did.  And  it  is  equally 
manifest  that  this  would  not  be  the  case  if  the  impulses  of 
the  waves  were  not  properly  timed;  for  then  the  motion 
imparted  to  the  pendulum  by  one  wave  would  be  neutral- 
ized by  another,  and  there  could  not  be  the  accumulation 
of  effect  obtained  when  the  periods  of  the  waves  correspond 
with  the  periods  of  the  pendulum.  So  much  for  the 
particular  impulses  absorbed  by  the  pendulum.  But  if 
such  a  pendulum  set  oscillating  in  air  could  produce  waves 
in  the  air,  it  is  evident  that  the  waves  it  would  produce 
would  be  of  the  same  period  as  those  whose  motions  it 
would  take  up  or  absorb  most  completely,  if  they  struck 
against  it. 

Perhaps  the  most  curious  effect  of  these  timed  impulses 
ever  described  was  that  observed  by  a  watchmaker,  named 
Ellicott,  in  the  year  1741.  He  left  two  clocks  leaning 
against  the  same  rail;  one  of  them,  which  we  may  call  A, 
was  set  going;  the  other  B,  not.  Some  time  afterward  he 
found,  to  his  surprise,  that  B  was  ticking  also.  The 
pendulums  being  of  the  same  length,  the  shocks  imparted 
by  the  ticking  of  A  to  the  rail  against  which  both  clocks 
rested  were  propagated  to  B,  and  were  so  timed  as  to  set  B 
going.  Other  curious  effects  were  at  the  same  time 
observed.  When  the  pendulums  differed  from  each  other 
a  certain  amount,  A  set  B  going,  but  the  reaction  of  B 
stopped  A.  Then  B  set  A  going,  and  the  reaction  of  A 
stopped  B.  When  the  periods  of  oscillation  were  close  to 
each  other,  but  still  not  quite  alike,  the  clocks  mutually 
controlled  each  other,  and  by  a  kind  of  compromise  they 
ticked  in  perfect  unison. 

But  what  has  all  this  to  do  with  our  present  subject? 
The  varied  actions  of  the  universe  are  all  modes  of  motion; 
and  the  vibration  of  a  ray  claims  strict  brotherhood  with 
the  vibrations  of  our  pendulum.  Suppose  ethereal  waves 
striking  upon  atoms  which  oscillate  in  the  same  periods  as 
the  waves,  the  motion  of  the  waves  will  be  absorbed  by  the 
atoms;  suppose  we  send  our  beam  of  white  light  through 
a  sodium  flame,  the  atoms  of  that  flame  will  be  chiefly 
affected  by  those  undulations  which  are  synchronous  with 
their  own  periods  of  vibration.  There  will  be  on  the  part 
of  those  particular  rays  a  transference  of  motion  from  the 
agitated  ether  to  the  atoms  of  the  volatilized  metal,  which, 
as  already  defined,  is  absorption, 


PHYSICAL  BASIS  OF  SOLAR  CHEMISTRY,        259 

The  experiment  justifying  this  conclusion  is  now  for 
the  first  time  to  be  made  before  a  public  audience.  -I  pass 
a  beam  through  our  two  prisms,  and  the  spectrum  spreads 
its  colors  upon  the  screen.  Between  the  lamp  and  the 
prism  I  interpose  a  snapdragon  light.  Alcohol  and 
water  are  here  mixed  with  common  salt,  and  the  metal 
dish  that  holds  them  is  heated  by  a  spirit-lamp.  The 
vapor  from  the  mixture  ignites  and  we  have  a  mono- 
chromatic flame.  Through  this  flame  the  beam  from  the 
lamp  is  now  passing;  and  observe  the  result  upon  the 
spectrum.  You  see  a  shady  band  cut  out  of  the  yellow — 
not  very  dark,  but  sufficiently  so  to  be  seen  by  everybody 
present. 

But  let  me  exalt  this  effect.  Placing  in  front  of  the 
electric  lamp  the  intense  flame  of  a  large  Bunsen's  burner, 
a  platinum  capsule  containing  a  bit  of  sodium  less  than  a 
pea  in  magnitude  is  plunged  into  the  flame.  The  sodium 
soon  volatilizes  and  burns  with  brilliant  incandescence. 
The  beam  crosses  the  flame,  and  at  the  same  time  the 
yellow  band  of  the  spectrum  is  clearly  and  sharply  cut  out, 
a  band  of  intense  darkness  occupying  its  place.  On  with- 
drawing the  sodium,  the  brilliant  yellow  of  the  spectrum 
takes  its  proper  place,  while  the  reiutroduction  of  the 
flame  causes  the  band  to  reappear. 

Let  me  be  more  precise:  The  yellow  color  of  the  spec- 
trum extends  over  a  sensible  space,  blending  on  one  side 
with  the  orange  and  on  the  other  with  the  green.  The 
term  "yellow  band"  is  therefore  somewhat  indefinite. 
This  vagueness  may  be  entirely  removed.  By  dipping  the 
carbon-point  used  for  the  positive  electrode  into  a  solution 
of  common  salt,  and  replacing  it  in  the  lamp,  the  bright 
yellow  band  produced  by  the  sodium  vapor  stands  out 
from  the  spectrum.  When  the  sodium  flame  is  caused  to 
act  upon  the  beam  it  is  that  particular  yellow  band  that 
is  obliterated,  an  intensely  black  streak  occupying  its 
place. 

An  additional  step  of  reasoning  leads  to  the  conclusion 
that  if,  instead  of  the  flame  of  sodium  alone,  we  were  to 
introduce  into  the  path  of  the  beam  a  flame  in  which 
lithium,  strontium,  magnesium,  calcium,  etc.,  are  in  a 
state  of  volatilization,  each  metallic  vapor  would  cut  out  a 
system  of  bands,  corresponding  exactly  in  position  with 
the  bright  bauds  of  the  same  metallic  vapor.  The 


260  FRAGMENTS  OF  SCIENCE. 

light  of  our  electric  lamp  shining  through  such  a  composite 
flame  would  give  us  a  spectrum  cut  up  by  dark  lines, 
exactly  as  the  solar  spectrum  is  cut  up  by  the  lines  of 
Fraunhofer. 

Thus  by  the  combination  of  the  strictest  reasoning  with 
the  most  conclusive  experiment,  we  reach  the  solution 
of  one  of  the  grandest  of  scientific  problems — the  constitu- 
tion of  the  sun.  The  sun  consists  of  a  nucleus  surrounded 
by  flaming  atmosphere.  The  light  of  the  nucleus  would 
give  us  a  continuous  spectrum,  like  that  of  our  common 
carbon-points;  but  having  to  pass  through  the  photosphere, 
as  our  beam  had  to  pass  through  the  flame,  those  rays  of 
the  nucleus  which  the  photosphere  can  itself  emit  are 
absorbed,  and  shaded  spaces,  corresponding  to  the  partic- 
ular rays  absorbed,  occur  in  the  spectrum.  Abolish  the 
solar  nucleus,  and  we  should  have  a  spectrum  showing  a 
bright  line  in  the  place  of  every  dark  line  of  Fraunhofer. 
These  lines  are  therefore  not  absolutely  dark,  but  dark  by 
an  amount  corresponding  to  the  difference  between  the 
light  of  the  nucleus  intercepted  by  the  photosphere,  and 
the  light  which  issues  from  the  latter. 

The  man  to  whom  we  owe  this  noble  generalization  is 
Kirchhoff,  professor  of  natural  philosophy  in  the  Uni- 
versity of  Heidelberg;  *  but,  like  every  other  great  dis- 
covery, it  is  compounded  of  various  elements.  Mr.  Talbot 
observed  the  bright  lines  in  the  spectra  of  colored  flames. 
Sixteen  years  ago  Dr.  Miller  gave  drawings  and  descriptions 
of  the  spectra  of  various  colored  flames.  Wheatstone, 
with  his  accustomed  iugenuity,  analyzed  the  light  of  the 
electric  spark,  and  showed  that  the  metals  between  which 
the  spark  passed  determined  the  bright  bands  in  the 
spectrum  of  the  spark.  Masson  published  a  prize  essay  on 
these  bands;  Van  der  Willigen,  and  more  recently  Plucker, 
have  given  us  beautiful  drawings  of  the  spectra,  obtained 
from  the  discharge  of  Ruhmkorif's  coil.  But  none  of  these 
distinguished  men  betrayed  the  least  knowledge  of  the 
connection  between  the  bright  bands  of  the  metals  and  the 
dark  lines  of  the  solar  spectrum.  The  man  who  came 
nearest  to  the  philosophy  of  the  subject  was  Angstrom. 
In  a  paper  translated  from  PoggendorfFs  Annalen  by 
myself,  and  published  in  the  Philosophical  Magazine 

*Now  professor  in  the  University  of  Berlin. 


ELEMEN TAR  7  MA  GNETISM.  261 

for  1855,  he  indicates  that  the  rays  which  a  body  absorbs 
are  precisely  those  which  it  can  emit  when  rendered 
luminous.  In  another  place,  he  speaks  of  one  of  his  spectra 
giving  the  general  impression  of  a  reversal  of  the  solar 
spectrum.  Foucault,  Stokes,  and  Thomson,  have  all  been 
very  close  to  the  discovery;  and,  for  my  own  part,  the 
examination  of  the  radiation  and  absorption  of  heat  by 
gases  and  vapors,  some  of  the  results  of  which  I  placed 
before  you  at  the  commencement  of  this  discourse,  would 
have  led  me  in  1859  to  the  law  on  which  all  Kirchhoff's 
speculations  are  founded,  had  not  an  accident  withdrawn 
me  from  the  investigation.  But  Kirchhoffs  claims  are 
unaffected  by  these  circumstances.  True,  much  that  I 
have  referred  to  formed  the  necessary  basis  of  his  dis- 
covery; so  did  the  laws  of  Kepler  furnish  to  Newton 
the  basis  of  the  theory  of  gravitation.  But  what  Kirch- 
hoff  has  done  carries  us  far  beyond  all  that  had  before 
been  accomplished.  He  has  introduced  the  order  of 
law  amid  a  vast  assemblage  of  empirical  observations, 
and  has  ennobled  our  previous  knowledge  by  showing 
its  relationship  to  some  of  the  most  sublime  of  natural 
phenomena. 


CHAPTER  XV. 

ELEMENTARY    MAGNETISM. 

A  LECTURE  TO  SCHOOLMASTERS. 

WE  HAVE  no  reason  to  believe  that  the  sheep  or  the  dog, 
or  indeed  any  of  the  lower  animals,  feel  an  interest  in  the 
laws  by  which  natural  phenomena  are  regulated.  A  herd 
may  be  terrified  by  a  thunderstorm;  birds  may  go  to  roost, 
and  cattle  return  to  their  stalls,  during  a  solar  eclipse; 
but  neither  birds  nor  cattle,  as  far  as  we  know,  ever  think 
of  inquiring  into  the  causes  of  these  things.  It  is  other- 
wise with  man.  The  presence  of  natural  objects,  the 
occurrence  of  natural  events,  the  varied  appearances  of  the 
universe  in  which  he  dwells,  penetrate  beyond  his  organs  of 
sense,  and  appeal  to  an  inner  power  of  which  the  senses 
are  the  mere  instruments  and  excitants.  No  fact  is  to 
him  either  original  or  final.  He  cannot  limit  himself  to 
the  contemplation  of  it  alone,  but  endeavors  to  ascertain 


262  FRAGMENTS  OF  SCIENCE. 

its  position  in  a  series  to  which  uniform  experience  assures 
him  it  must  belong.  He  regards  all  that  he  witnesses  in 
the  present  as  the  efflux  and  sequence  of  something  that 
has  gone  before,  and  as  the  source  of  a  system  of  events 
which  is  to  follow.  The  notion  of  spontaneity,  by  which 
in  his  ruder  state  he  accounted  for  natural  events,  is 
abandoned;  the  idea  that  Nature  is  an  aggregate  of  in- 
dependent parts  also  disappears,  as  the  connection  and 
mutual  dependence  of  physical  powers  become  more  and 
more  manifest:  until  he  is  finally  led  to  regard  Nature  as 
an  organic  whole — as  a  body  each  of  whose  members  sym- 
pathizes with  the  rest,  changing,  it  is  true,  from  age  to 
age,  but  changing  without  break  of  continuity  in  the  rela- 
tion of  cause  and  effect. 

The  system  of  things  which  we  call  Nature  is,  however, 
too  vast  and  various  to  be  studied  first-hand  by  any  single 
mind.  As  knowledge  extends  there  is  always  a  tendency 
to  subdivide  the  field  of  investigation.  Its  various  parts 
are  taken  up  by  different  minds,  and  thus  receive  a  greater 
amount  of  attention  than  could  possibly  be  bestowed  on 
them  if  each  investigator  aimed  at  the  mastery  of  the  whole. 
The  centrifugal  form  in  which  knowledge,  as  a  whole,  ad- 
vances, spreading  ever  wider  on  all  sides,  is  due  in  reality  to 
the  exertions  of  individuals,  each  of  whom  directs  his  efforts, 
more  or  less,  along  a  single  line.  Accepting,  in  many  re- 
spects, his  culture  from  his  fellow-men — taking  it  from 
spoken  words  or  from  written  books — in  some  one  direction, 
the  student  of  Nature  ought  actually  to  touch  his  work. 
He  may  otherwise  be  a  distributor  of  knowledge,  but  not 
a  creator,  and  he  fails  to  attain  that  vitality  of  thought, 
and  correctness  of  judgment,  which  direct  and  habitual 
contact  with  natural  truth  can  alone  impart. 

One  large  department  of  the  system  of  Nature  which 
forms  the  chief  subject  of  my  own  studies,  and  to  which 
it  is  my  duty  to  call  your  attention  this  evening,  is  that  of 
physics,  or  natural  philosophy.  This  term  is  large  enough 
to  cover  the  study  of  Nature  generally,  but  it  is  usually  re- 
stricted to  a  department  which,  perhaps,  lies  closer  to  our 
perceptions  than  any  other.  It  deals  with  the  phenomena 
and  laws  of  light  and  heat — with  the  phenomena  and  laws 
of  magnetism  and  electricity — with  those  of  sound — with 
the  pressures  and  motions  of  liquids  and  gases,  whether  at 
rest  or  in  a  state  of  translation  or  of  undulation.  The 


ELEMENTARY  MAGNETISM.  263 

science  of  mechanics  is  a  portion  of  natural  philosophy, 
though  at  present  so  large  as  to  need  the  exclusive  attention 
of  him  who  would  cultivate  it  profoundly.  Astronomy  is  the 
application  of  physics  to  the  motions  of  the  heavenly  bodies, 
the  vastnessof  the  field  causing  it,  however,  to  be  regarded  as 
a  department  in  itself.  In  chemistry  physical  agents  play 
important  parts.  By  heat  and  light  we  cause  atoms  and 
molecules  to  unite  or  to  fall  asunder.  Electricity  exerts  a 
similar  power.  Through  their  ability  to  separate  nutritive 
compounds  into  their  constituents,  the  solar  beams  build 
up  the  whole  vegetable  world,  and  by  it  the  animal  world. 
The  touch  of  the  selfsame  beams  causes  hydrogen  and 
chlorine  to  unite  with  sudden  explosion,  and  to  form  by 
their  combination  a  powerful  acid.  Thus  physics  and 
chemistry  intermingle.  Physical  agents  are,  however,  em- 
ployed by  the  chemist  as  a  means  to  an  end;  while  in 
physics  proper  the  laws  and  phenomena  of  the  agents  them- 
selves, both  qualitative  and  quantitative,  are  the  primary 
objects  of  attention. 

My  duty  here  to-night  is  to  spend  an  hour  in  telling  how 
this  subject  is  to  be  studied,  and  how  a  knowledge  of  it  is 
to  be  imparted  to  others.  From  the  domain  of  physics, 
which  would  be  unmanageable  as  a  whole,  I  select  as  a 
sample  the  subject  of  magnetism.  I  might  readily  enter- 
tain you  on  the  present  occasion  with  an  account  of  what 
natural  philosophy  has  accomplished.  I  might  point  to 
those  applications  of  science  of  which  we  hear  so  much  in 
the  newspapers,  and  which  are  so  often  mistaken  for 
science  itself.  I  might,  of  course,  ring  cha'nges  on  the 
steam-engine  and  the  telegraph,  the  electrotype  and  the 
photograph,  the  medical  applications  of  physics,  and  the 
various  other  inlets  by  which  scientific  thought  filters  into 
practical  life.  That  would  be  easy  compared  with  the  task 
of  informing  you  how  you  are  to  make  the  study  of  physics 
the  instrument  of  your  pupil's  culture;  how  you  are  to 
possess  its  facts  and  make  them  living  seeds  which  shall 
take  root  and  grow  in  the  mind,  and  not  lie  like  dead 
lumber  in  the  storehouse  of  memory.  This  is  a  task  much 
heavier  than  the  mere  recounting  of  scientific  achievements; 
and  it  is  one  which,  feeling  my  own  want  of  time  to  execute 
it  aright,  I  might  well  hesitate  to  accept. 

But  let  me  sink  excuses,  and  attack  the  work  before  me. 
First  and  foremost,  then,  I  would  advise  you  to  get  a 


264  FRAGMENTS  OF  SCIENCE. 

knowledge  of  facts  from  actual  observation.  Facts  looked 
at  directly  are  vital;  when  they  pass  into  words  half  the 
sap  is  taken  out  of  them.  You  wish,  for  example,  to  get 
a  knowledge  of  magnetism;  well,  provide  yourself  with  a 
good  book  on  the  subject,  if  you  can,  but  do  not  be  con- 
tent with  what  the  book  tells  you;  do  not  be  satisfied  with 
its  descriptive  woodcuts;  see  the  operations  of  the  force 
yourself.  Half  of  our  book  writers  describe  experiments 
which  they  never  made,  and  their  descriptions  often  lack 
both  force  and  truth;  but  no  matter  how  clever  or  con- 
scientious they  maybe,  their  written  words  cannot  supply 
the  place  of  actual  observation.  Every  fact  has  numerous 
radiations,  which  are  shorn  off  by  the  man  who  describes 
it.  Go,  then,  to  a  philosophical  instrument  maker,  and 
give  a  shilling  or  half  a  crown  fora  straight  bar-magnet,  or, 
if  you  can  afford  it,  purchase  a  pair  of  them;  or  get  a 
smith  to  cut  a  length  of  ten  inches  from  a  bar  of  steel  an 
inch  wide  and  half  an  inch  thick;  file  its  ends  smoothly, 
harden  it,  and  get  somebody  like  myself  to  magnetize  it. 
Procure  some  darning  needles,  and  also  a  little  unspun 
silk,  which  will  give  you  a  suspending  fiber  void  of  torsion. 
Make  a  little  loop  of  paper,  or  of  wire,  and  attach  your 
fiber  to  it.  Do  it  neatly.  In  the  loop  place  a  darning- 
needle,  and  bring  the  two  ends  or  poles,  as  they  are  called,  of 
your  bar-magnet  successively  up  to  the  ends  of  the  needle. 
Both  the  poles,  you  find,  attract  both  ends  of  the  needle. 
Replace  the  needle  by  a  bit  of  annealed  iron  wire;  the 
same  effects  ensue.  Suspend  successively  little  rods  of 
lead,  copper*  silver,  brass,  wood,  glass,  ivory,  or  whale- 
bone; the  magnet  produces  no  sensible  effect  upon  any  of 
the  substances.  You  thence  infer  a  special  property  in 
the  case  of  steel  and  iron.  Multiply  your  experiments, 
however,  and  you  will  find  that  some  other  substances, 
besides  iron  and  steel,  are  acted  upon  by  your  magnet.  A 
rod  of  the  metal  nickel,  or  of  the  metal  cobalt,  from  which 
the  blue  color  used  by  painters  is  derived,  exhibits  powers 
similar  to  those  observed  with  the  iron  and  steel. 

In  studying  the  character  of  the  force  you  may,  however, 
confine  yourself  to  iron  and  steel,  which  are  always  at  hand. 
Make  your  experiments  with  the  darning-needle  over  and 
over  again;  operate  on  both  ends  of  the  needle;  try  both 
ends  of  the  magnet.  Do  not  think  the  work  dull;  you  are 
conversing  with  Nature,  and  must  acquire  over  her  lau- 


ELEMENTAL  T  MA  ONETISM.  265 

guage  a  certain  grace  and  mastery,  which  practice  can 
alone  impart.  Let  overy  movement  be  made  with  care,  and 
avoid  slovenliness  from  the  outset.  Experiment,  as  I  have 
said,  is  the  language  by  which  we  address  Nature,  and 
through  which  she  sends  her  replies;  in  the  use  of  this 
language  a  lack  of  straightforwardness  is  as  possible,  and 
as  prejudicial,  as  in  the  spoken  language  of  the  tongue. 
If,  therefore,  you  wish  to  become  acquainted  with  the 
truth  of  Nature,  you  must  from  the  first  resolve  to  deal 
with  her  sincerely. 

Now  remove  your  needle  from  its  loop,  and  draw  it 
from  eye  to  point  along  one  of  the  ends  of  the  magnet; 
res u spend  it,  and  repeat  your  former  experiment.  You 
now  find  that  each  extremity  of  the  magnet  attracts  one 
end  of  the  needle,  and  repels  the  other.  The  simple 
attraction  observed  in  the  first  instance,  is  now  replaced 
by  a  dual  force.  Repeat  the  experiment  till  you  have 
thoroughly  observed  the  ends  which  attract  and  those 
which  repel  each  other. 

Withdraw  the  magnet  entirely  from  the  vicinity  of  your 
needle,  arid  leave  the  latter  freely  suspended  by  its  fiber. 
Shelter  it  as  well  as  you  can  from  currents  of  air,  and  if 
you  have  iron  buttons  on  your  coat,  or  a  steel  penknife  in 
your  pocket,  beware  of  their  action.  If  you  work  at  night, 
beware  of  iron  candlesticks,  or  of  brass  ones  with  iron  rods 
inside.  Freed  from  such  disturbances,  the  needle  takes  np 
a  certain  determinate  position.  It  sets  its  length  nearly 
north  and  south.  Draw  it,  aside  and  let  it  go.  After 
several  oscillations  it  will  again  come  to  the  same  position. 
If  you  have  obtained  your  magnet  from  a  philosophical  in- 
strument maker,  you  will  see  a  mark  on  one  of  its  ends.  Sup- 
posing, then,  that  you  drew  your  needle  along  the  end 
thus  marked?  and  that  the  point  of  your  needle  was  the 
last  to  quit  the  magnet,  you  will  find  that  the  point  turns 
to  the  south,  the  eye  of  the  needle  turning  toward  the 
north.  Make  sure  of  this,  and  do  not  take  the  statement 
on  my  authority. 

Now  take  a  second  darning-needle  like  the  first,  and 
magnetize  it  in  precisely  the  same  manner;  freely  suspended 
it  also  will  turn  its  eye  to  the  north  and  its  point  to  the 
south.  Your  next  step  is  to  examine  the  action  of  the  two 
needles  which  you  have  thus  magnetized  upon  each  other. 

Take  one  of  them  in  your  hand,  and  leave  the  other  sus^ 


266  FRAGMENTS  OF  SCIENCE. 

pended;  bring  the  eye-end  of  the  former  near  the  eye-end 
of  the  latter;  the  suspended  needle  retreats:  it  is  repelled. 
Make  the  same  experiment  with  the  two  points;  you  obtain 
the  same  result,  the  suspended  needle  is  repelled.  Now 
cause  the  dissimilar  ends  to  act  on  each  other — you  have 
attraction — point  attracts  eye,  and  eye  attracts  point. 
Prove  the  reciprocity  of  this  action  by  removing  the  sus- 
pended needle,  and  putting  the  other  in  its  place.  You 
obtain  the  same  result.  The  attraction,  then,  is  mutual, 
and  the  repulsion  is  mutual.  You  have  thus  demonstrated 
in  the  clearest  manner  the  fundamental  law  of  magnetism, 
that  like  poles  repel,  and  that  unlike  poles  attract  each 
other.  You  may  say  that  this  is  all  easily  understood 
without  doing;  but  do  it,  and  your  knowledge  will  not  be 
confined  to  what  i  have  uttered  here. 

I  have  said  that  one  end  of  your  bar-magnet  has  a  mark 
upon  it;  lay  several  silk  fibers  together,  so  as  to  get 
sufficient  strength,  or  employ  a  thin  silk  ribbon,  and  form 
a  loop  large  enough  to  hold  your  magnet.  Suspend  it; 
it  turns  its  marked  end  toward  the  north.  This  marked 
end  is  that  which  in  England  is  called  the  north  pole.  If 
a  common  smith  has  made  your  magnet,  it  will  be  con- 
venient to  determine  its  north  pole  yourself,  and  to  mark 
it  with  a  file.  Vary  your  experiments  by  causing  your 
magnetized  darning-needle  to  attract  and  repel  your  large 
magnet;  it  is  quite  competent  to  do  so.  In  magnetizing 
the  needle,  I  have  supposed  the  point  to  be  the  last  to  quit 
the  marked  end  of  the  magnet;  the  point  of  the  needle  is 
a  south  pole.  The  end  which  last  quits  the  magnet  is 
always  opposed  in  polarity  to  the  end  of  the  magnet  with 
which  it  has  been  last  in  contact. 

You  may  perhaps  learn  all  this  in  a  single  hour;  but 
spend  several  at  it,  if  necessary;  and  remember,  under- 
standing it  is  not  sufficient:  you  must  obtain  a  manual 
aptitude  in  addressing  Nature.  If  you  speak  to  your 
fellow-man  you  are  not  entitled  to  use  jargon.  Bad  ex- 
periments are  jargon  addressed  to  Nature,  and  just  as 
much  to  be  deprecated.  Manual  dexterity  in  illustrating 
the  interaction  of  magnetic  poles  is  of  the  utmost  impor- 
tance at  this  stage  of  your  progress;  and  you  must  not 
neglect  attaining  this  power  over  your  implements.  As 
you  proceed,  moreover,  you  will  be  tempted  to  do  more 
than  I  can  possibly  suggest.  Thoughts  will  occur  to  you 


ELEMENTARY  MAGNETISM.  267 

which  you  will  endeavor  to  follow  out:  questions  will 
arise  which  you  will  try  to  answer.  The  same  experiment 
may  be  twenty  different  things  to  twenty  people.  Having 
witnessed  the  action  of  pole  on  pole,  through  the  air,  you 
will  perhaps  try  whether  the  magnetic  power  is  not  to  be 
screened  off.  You  use  plates  of  glass,  wood,  slate,  paste- 
board, or  gutta-percha,  but  find  them  all  pervious  to  this 
wondrous  force.  One  magnetic  pole  acts  upon  another 
through  these  bodies  as  if  they  were  not  present.  Should 
you  ever  become  a  patentee  for  the  regulation  of  ships' 
compasses,  you  will  not  fall,  as  some  projectors  have  done, 
into  the  error  of  screening  off  the  magnetism  of  the 
ship  by  the  interposition  of  such  substances. 

If  you  wish  to  teach  a  class  you  must  contrive  that  the 
effects  which  you  have  thus  far  witnessed  for  yourself  shall 
be  witnessed  by  twenty  or  thirty  pupils.  And  here  your 
private  ingenuity  must  come  into  play.  You  will  attach 
bits  of  paper  to  your  needles,  so  as  to  render  their  move- 
ments visible  at  a  distance,  denoting  the  north  and  south 
poles  by  different  colors,  say  green  and  red.  You  may  also 
improve  upon  your  darning-needle.  Take  a  strip  of  sheet 
steel,  heat  it  to  vivid  redness  and  plunge  it  into  cold 
water.  It  is  thereby  hardened;  rendered,  in  fact,  almost  as 
brittle  as  glass.  Six  inches  of  this,  magnetized  in  the 
manner  of  the  darning-needle,  will  be  better  able  to  carry 
your  paper  indexes.  Having  secured  such  a  strip,  you 
proceed  thus: 

Magnetize  a  small  sewing-needle  and  determine  its 
poles;  or,  break  half  an  inch,  or  an  inch,  off  your  magnet- 
ized darning-needle  and  suspend  it  by  a  fine  silk  fiber. 
The  sewing-needle,  or  the  fragment  of  the  darning-needle, 
is  now  to  be  used  as  a  test-needle,  to  examine  the  distribu- 
tion of  the  magnetism  in  your  strip  of  steel.  Hold  the 
strip  upright  in  your  left  hand,  and  cause  the  test-needle 
to  approach  the  lower  end  of  your  strip;  one  end  of  the 
test-needle  is  attracted,  the  other  is  repelled.  Raise  your 
needle  along  the  strip;  its  oscillations,  which  at  first  were 
quick,  become  slower;  opposite  the  middle  of  the  strip  they 
cease  entirely;  neither  end  of  the  needle  is  attracted;  above 
the  middle  the  test-needle  turns  suddenly  round,  its  other 
end  being  now  attracted.  Go  through  the  experiment 
thoroughly:  you  thus  learn  that  the  entire  lower  half  of 
the  strip  attracts  one  end  of  the  needle,  while  the  entire 


268  FRAGMENTS  Of  SCIENCE. 

upper  half  attracts  the  opposite  end.  Supposing  the 
north  end  of  your  little  needle  to  be  that  attracted  below, 
you  infer  that  the  entire  lower  half  of  your  magnetized 
strip  exhibits  south  magnetism,  while  the  entire  upper 
half  exhibits  north  magnetism.  So  far,  then,  you  have 
determined  the  distribution  of  magnetism  in  your  strip  of 
steel. 

You  look  at  this  fact,  you  think  of  it;  in  its  suggestive- 
ness  the  value  of  an  experiment  chiefly  consists.  The 
thought  naturally  arises:  "  What  will  occur  if  I  break  my 
strip  of  steel  across  in  the  middle?  Shall  I  obtain  two 
magnets  each  possessing  a  single  pole?"  Try  the  experi- 
ment; break  your  strip  of  steel,  and  test  each  half  as  you 
tested  the  whole.  The  mere  presentation  of  its  two  ends 
in  succession  to  your  test-needle  suffices  to  show  that  you 
have  not  a  magnet  with  a  single  pole — that  each  half 
possesses  two  poles  with  a  neutral  point  between  them. 
And  if  you  again  break  the  half  into  two  other  halves,  you 
will  find  that  each  quarter  of  the  original  strip  exhibits 
precisely  the  same  magnetic  distribution  as  the  whole  strip. 
You  may  continue  the  breaking  process:  no  matter  how 
small  your  fragment  may  be,  it  still  possesses  two  opposite 
poles  and  a  neutral  point  between  them.  Well,  your  hand 
ceases  to  break  where  breaking  becomes  a  mechanical 
impossibility;  but  does  the  mind  stop  there?  No:  you 
follow  the  breaking  process  in  idea  when  you  can  no  longer 
realize  it  in  fact;  your  thoughts  wander  amid  the  very 
atoms  of  your  steel,  and  you  conclude  that  each  atom  is  a 
magnet,  and  that  the  force  exerted  by  the  strip  of  steel  is 
the  mere  summation,  or  resultant,  of  the  force  of  its 
ultimate  particles. 

Here,  then,  is  an  exhibition  of  power  which  we  can  call 
forth  at  pleasure  or  cause  to  disappear.  We  magnetize  our 
strip  of  steel  by  drawing  it  along  the  pole  of  a  magnet;  we 
can  demagnetize  it,  or  reverse  its  magnetism,  by  properly 
drawing  it  along  the  same  pole  in  the  opposite  direction. 
What,  then,  is  the  real  nature  of  this  wondrous  change? 
AVhat  is  it  that  takes  place  among  the  atoms  of  the  steel  when 
the  substance  is  magnetized  ?  The  question  leads  us  beyond 
the  region  of  sense,  and  into  that  of  imagination.  This 
faculty,  indeed,  is  the  divining-rod  of  the  man  of  science. 
Not,  however,  an  imagination  which  catches  its  creations 
from  the  air,  but  one  informed  and  inspired  by  facts; 


ELEMENTARY  MAtiNKTISM.  £69 

capable  of  seizing  firmly  ou  a  physical  image  as  a  principle, 
of  discerning  its  consequences,  and  of  devising  means 
whereby  these  forecasts  of  thought  may  be  brought  to  an 
experimental  test.  If  such  a  principle  be  adequate  to 
account  for  all  the  phenomena — if  from  an  assumed  cause 
the  observed  acts  necessarily  follow,  we  call  the  assumption 
a  theory,  and,  once  possessing  it,  we  can  not  only  revive  at 
pleasure  facts  already  known,  but  we  can  predict  others 
which  we  have  never  seen.  Thus,  then,  in  the  prosecution 
of  physical  science,  our  powers  of  observation,  memory, 
imagination,  and  inference,  are  all  drawn  upon.  We 
observe  facts  and  store'  them  up;  the  constuctive  imagi- 
nation broods  upon  these  memories,  tries  to  discern  their 
interdependence  and  weave  them  to  an  organic  whole. 
The  theoretic  principle  flashes  or  slowly  dawns  upon  the 
mind;  and  then  the  deductive  faculty  interposes  to  carry 
out  the  principle  to  its  logical  consequences.  A  perfect 
theory  gives  dominion  over  natural  facts;  and  even  an 
assumption  which  can  only  partially  stand  the  test  of  a 
comparison  with  facts,  may  be  of  eminent  use  in  enabling 
us  to  connect  and  classify  groups  of  phenomena.  The 
theory  of  magnetic  fluids  is  of  this  latter  character,  and 
with  it  we  must  now  make  ourselves  familiar. 

With  the  view  of  stamping  the  thing  more  firmly  on. 
your  minds,  I  will  make  use  of  a  strong  and  vivid  image. 
In  optics,  red  and  green  are  called  complementary  colors; 
their  mixture  produces  white.  Now  I  ask  you  to  imagine 
each  of  these  colors  to  possess  a  self-repulsive  power;  that 
red  repels  red,  that  green  repels  green;  but  that  red 
attracts  green  and  green  attracts  red,  the  attraction  of  the 
dissimilar  colors  being  equal  to  the  repulsion  of  the  similar 
ones.  Imagine  the  two  colors  mixed  so  as  to  produce 
white,  and  suppose  two  strips  of  wood  painted  with  this 
white;  what  will  be  their  action  upon  each  other?  Sus- 
pend one  of  them  freely  as  we  suspended  our  darning- 
needle,  and  bring  the  other  near  it;  what  will  occur?  The 
red  component  of  the  strip  you  hold  in  your  hand  will 
repel  the  red  component  of  your  suspended  strip;  but  then 
it  will  attract  the  green,  and  the  forces  being  equal,  they 
neutralize  each  other.  In  fact,  the  least  reflection  shows 
you  that  the  strips  will  be  as  indifferent  to  each  other  as 
two  unmagnetized  darning-needles  would  be,  under  the 
same  circumstances. 


270  FRAGMENTS  OF  SCIENCE. 

But  suppose,  instead  of  mixing  the  colors,  we  painted 
one  half  of  each  strip  from  center  to  end  red,  and  the 
other  half  green,  it  is  perfectly  manifest  that  the  two  strips 
would  now  behave  toward  each  othe'r  exactly  as  our  two 
magnetized  darning-needles — the  red  end  would  repel  the 
red  and  attract  the  green,  the  green  would  repel  the  green 
and  attract  the  red;  so  that,  assuming  two  colors  thus 
related  to  each  other,  we  could  by  their  mixture  produce 
the  neutrality  of  an  unmagnetized  body,  while  by  their 
separation  we  could  produce  the  duality  of  action  of  mag- 
netized bodies. 

But  you  have  already  anticipated  a  defect  in  my  con- 
ception; for  if  we  break  one  of  our  strips  of  wood  in  the 
middle  we  nave  one  half  entirely  red,  and  the  other  entirely 
green,  and  with  these  it  would  be  impossible  to  imitate  the 
action  of  our  broken  magnet.  How,  then,  must  we  modify 
our  conception;'  We  must  evidently  suppose  each  mole- 
cule of  the  wood  painted  green  on  one  face  and  red  on  the 
opposite  one.  The  resultant  action  of  all  the  atoms  would 
then  exactly  resemble  the  action  of  a  magnet.  Here  also, 
if  the  two  opposite  colors  of  each  atom  could  be  caused  to 
mix  so  as  to  produce  white,  we  should  have,  as  before,  per- 
fect neutrality. 

For  these  two  self-repellent  and  mutually  attractive 
colors,  substitute  in  your  minds  two  invisible  self -repel- 
lent and  mutually  attractive  fluids,  which  in  ordinary 
steel  are  mixed  to  form  a  neutral  compound,  but  which 
the  act  of  magnetization  separates  from  each  other, 
placing  the  opposite  fluids  on  the  opposite  face  of  each 
molecule.  You  have  then  a  perfectly  distinct  conception 
of  the  celebrated  theory  of  magnetic  fluids.  The  strength 
of  the  magnetism  excited  is  supposed  to  be  proportional  to 
the  quantity  of  neutral  fluid  decomposed.  According  to 
this  theory  nothing  is  actually  transferred  from  the  excit- 
ing magnet  to  the  excited- steel.  The  act  of  magnetiza- 
tion consists  in  the  forcible  separation  of  two  fluids  which 
existed  in  the  steel  before  it  was  magnetized,  but  which 
then  neutralized  each  other  by  their  coalescence.  And  if 
you  test  your  magnet,  after  it  has  excited  a  hundred  pieces 
of  steel,  you  will  find  that  it  has  lost  no  force — no  more, 
indeed,  than  I  should  lose,  had  my  words  such  a  magnetic 
influence  on  your  minds  as  to  excite  in  them  a  strong  re- 
solve to  study  natural  philosophy.  I  should  rather  be  the 


ELEMENT  AH  T  MA  QNETISM.  271 

gainer  by  my  own  utterance,  and  by  the  reaction  of  your 
fervor.  The  magnet  also  is  the  gainer  by  the  reaction  of 
the  body  which  it  magnetizes. 

Look  now  to  your  excited  piece  of  steel;  figure  each 
molecule  with  its  opposed  fluids  spread  over  its  opposite 
faces.  How  can  this  state  of  tilings  be  permanent?  The 
fluids,  by  hypothesis,  attract  each  other;  what  then,  keeps 
them  apart?  Why  do  they  not  instantly  rush  together 
across  the  equator  of  the  atom,  and  thus  neutralize  each 
other?  To  meet  this  question  philosophers  have  been 
obliged  to  infer  the  existence  of  a  special  force,  which 
holds  the  fluids  asunder.  They  call  it  coercive  force',  and 
it  is  found  that  those  kinds  of  steel  which  offer  most 
resistance  to  being  magnetized — which  require  the  greatest 
amount  of  "coercion"  to  tear  their  fluids  asunder — are  the 
very  ones  which  offer  the  greatest  resistance  to  the  reunion 
of  the  fluids,  after  they  have  been  once  separated.  Such 
kinds  of  steel  are  most  suited  to  the  formation  of  per- 
manent magnets.  It  is  manifest,  indeed,  that  without 
coercive  force  a  permanent  magnet  would  not  be  at  all 
possible. 

Probably  long  before  this  you  will  have  dipped  the  end 
of  your  magnet  among  iron  filings,  and  observed  how  they 
cling  to  it;  or  into  a  nail-box,  and  found  how  it  drags  the 
nails  after  it.  I  know  very  well  that  if  you  are  not  the 
slaves  of  routine,  you  will  have  by  this  time  done  many 
things  that  I  have  not  told  you  to  do,  and  thus  multiplied 
your  experience  beyond  what  I  have  indicated.  You  are 
almost  sure  to  have  caused  a  bit  of  iron  to  hang  from  the 
end  of  your  magnet,  and  you  have  probably  succeeded  in 
causing  a  second  bit  to  attach  itself  to  the  first,  a  third 
to  the  second;  until  finally  the  force  has  become  too  feeble 
to  bear  the  weight  of  more.  If  you  have  operated  with 
nails,  you  may  have  observed  that  the  points  and  edges 
hold  together  with  the  greatest  tenacity;  and  that  a  bit  of 
iron  clings  more  firmly  to  the  corner  of  your  magnet  than 
to  one  of  its  flat  surfaces.  In  short,  you  will  in  all  likeli- 
hood have  enriched  your  experience  in  many  ways  without 
any  special  direction  from  me. 

Well,  the  magnet  attracts  the  nail,  and  the  nail  attracts 
a  second  one.  This  proves  that  the  nail  in  contact  with 
the  magnet  has  had  the  magnetic  quality  developed  in  it 
by  that  contact.  If  it  be  withdrawn  from  the  magnet  its 


272  FRAGMENTS  OF  SCIENCE. 

power  to  attract  its  fellow  nail  ceases.  Contact,  however, 
is  not  necessary.  A  sheet  of  glass  or  paper,  or  a  space  of 
air,  may  exist  between  the  magnet  and  the  nail;  the  latter 
is  still  magnetized,  though  not  so  forcibly  as  when  in  actual 
contact.  The  nail  thus  presented  to  the  magnet  is  itself  a 
temporary  magnet.  That  end  which  is  turned  toward  the 
magnetic  pole  has  the  opposite  magnetism  of  the  pole 
which  excites  it;  the  end  most  remote  from  the  pole  has 
the  same  magnetism  as  the  pole  itself,  and  between  the 
two  poles,  the  nail,  like  the  magnet,  possesses  a  magnetic 
equator. 

Conversant  as  you  now  are  with  the  theory  of  magnetic 
fluids,  you  have  already,  I  doubt  not,  anticipated  me  in  im- 
agining the  exact  condition  of  an  iron  nail  under  the  influ- 
ence of  the  magnet.  You  picture  the  iron  as  possessing 
the  neutral  fluid  in  abundance;  you  picture  the  magnetic 
pole,  when  brought  near,  decomposing  the  fluid;  repelling 
the  fluid  of  a  like  kind  with  itself,  and  attracting  the  un- 
like fluid;  thus  exciting  in  the  parts  of  the  iron  nearest  to 
itself  the  opposite  polarity.  But  the  iron  is  incapable  of 
becoming  a  permanent  magnet.  It  only  shows  its  virtue 
as  long  as  the  magnet  acts  upon  it.  What,  then,  does  the 
iron  lack  which  the  steel  possesses?  It  lacks  coercive  force. 
Its  fluids  are  separated  with  ease;  but,  once  the  separating 
cause  is  removed,  they  flow  together  again,  and  neutrality 
is  restored.  Imagination  must  be  quite  nimble  in  picturing 
these  changes — able  to  see  the  fluids  dividing  and  reuniting, 
according  as  the  magnet  is  brought  near  or  withdrawn. 
Fixing  a  definite  pole  in  your  mind,  you  must  picture  the 
precise  arrangement  of  the  two  fluids  with  reference  to 
this  pole,  and  be  able  to  arouse  similar  pictures  in  the  minds 
of  your  pupils.  You  will  cause  them  to  place  magnets  and 
iron  in  various  positions,  and  describe  the  exact  magnetic 
state  of  the  iron  in  each  particular  case.  The  mere  facts 
of  magnetism  will  have  their  interest  immensely  augmented 
by  an  acquaintance  with  the  principles  whereon  the  facts 
depend.  Still,  while  you  use  this  theory  of  magnetic  fluids 
to  track  out  the  phenomena  and  link  them  together,  you 
will  not  forget  to  tell  your  pupils  that  it  is  to  be  regarded 
as  a  symbol  merely — a  symbol,  moreover,  which  is  incom- 
petent to  cover  all  the  facts,*  but  which  does  good  practU 

*This  theory  breaks  down  when  applied  to  diamagnetic  bodies 
which  are  repelled  by  magnets.  Like  soft  iron,  such  bodies  are 


KL T3X1SNTA  HY  MA GNKT1SM.  tf$ 

cal  service  while  we  are  waiting  for  the  actual  truth  to 
become  known. 

The  state  of  excitement  into  which  iron  is  thrown  by  the 
influence  of  a  magnet  is  sometimes  called  "  magnetization 
by  influence."  More  commonly,  however,  the  magnetism  is 
said  to  be  "  induced  "  in  the  iron,  and  hence  this  mode  of 
magnetizing  is  called  "  magnetic  induction."  Now  there 
is  nothing  theoretically  perfect  in  Nature:  there  is  no  iron 
so  soft  as  not  to  possess  a  certain  amount  of  coercive  force, 
and  no  steel  so  hard  as  not  to  be  capable,  in  some  degree, 
of  magnetic  induction.  The  quality  of  steel  is  in  some 
measure  possessed  by  iron,  and  the  quality  of  iron  is  shared 
in  some  degree  bv  steel.  It  is  in  virtue  of  this  latter  fact 
that  the  unmagnetized  darning-needle  was  attracted  in 
your  first  experiment;  and  from  this  you  may  at  once  de- 
duce the  consequence  that,  after  the  steel  has  been  mag- 
netized, the  repulsive  action  of  a  magnet  must  be  always 
less  than  its  attractive  action.  For  the  repulsion  is  opposed 
by  the  inductive  action  of  the  magnet  on  the  steel,  while 
the  attraction  is  assisted  by  the  same  inductive  action. 
Make  this  clear  to  your  minds,  and  verify  it  by  your  exper- 
iments. In  some  cases  you  can  actually  make  the  attrac- 
tion due  to  the  temporary  magnetism  overbalance  the 
repulsion  due  to  the  permanent  magnetism,  and  thus  cause 
two  poles  of  the  same  kind  apparently  to  attract  each  other. 
When,  however,  good  hard  magnets  act  on  each  other  from 
a  sufficient  distance,  the  inductive  action  practically  van- 
ishes, and  the  repulsion  of  like  poles  is  sensibly  equal  to 
the  attraction  of  unlike  ones. 

I  dwell  thus  long  on  elementary  principles,  because  they 
are  of  the  first  importance,  and  it  is  the  temptation  of  this 
age  of  unhealthy  cramming  to  neglect  them.  Now  follow 
me  a  little  farther.  In  examining  the  distribution  of 
magnetism  in  your  strip  of  steel  you  raised  the  needle 
slowly  from  bottom  to  top,  and  found  what  we  called  a 
neutral  point  at  the  center.  Now  does  the  magnet  really 
exert  no  influence  on  the  pole  presented  to  its  center?  Let 
us  see. 

Let  s  if,  fig.  11,  be  our  magnet,  and  let  n  represent  a 
particle  of  north  magnetism  placed  exactly  opposite  the 
middle  of  the  magnet.  Of  course  this  is  an  imaginary  case, 

thrown  "into  a  state  of  temporary  excitement,  in  virtue  of  which  they 
are  repelled;  but  any  attempt  to  explain  such  a  repulsion  by  the  de- 
composition of  a  fluid  will  demonstrate  its  own  futility. 


274  FRAGMENTS  OF  SCIENCE. 

as  you  can  never  in  reality  thus  detach  your  north  magnet- 
ism from  its  neighbor.  But  supposing  us  to  have  done  so, 
what  would  be  the  action  of  the  two  poles  of  the  magnet 
on  n  f  Your  reply  will  of  course  be  that  the  pole  s  attracts 
n  while  the  pole  N  repels  it.  Let  the  magnitude  and  direc- 
tion of  the  attraction  be  expressed  by  the  line  n  m,  and  the 
magnitude  and  direction  of  the  repulsion  by  the  line  n  o. 
Now,  the  particle  n  being  equally  distant  from  s  and  N, 
the  line  n  o,  expressing  the  repulsion,  will  be  equal  to  m  n, 
which  expresses  the  attraction.  Acted  upon  by  two  such 
forces,  the  particle  n  must  evidently  move  in  the  direction 
n  p,  exactly  midway  between  m  n  and  n  o.  Hence  you  see 
that  although  there  is  no  tendency  of  the  particle  n  to 
move  toward  the  magnetic  equator,  there  is  a  tendency  on 
its  part  to  move  parallel  to  the  magnet.  If,  instead  of  a 
particle  of  north  magnetism,  we  placed  a  particle  of  south 
magnetism  opposite  to  the  magnetic  equator,  it  would  evi- 


s  i-  i  «i  ir 

Fio.  11. 

dently  be  urged  along  the  line  n  q;  and  if,  instead  of  two 
separate  particles  of  magnetism  we  place  a  little  magnetic 
needle,  containing  both  north  and  south  magnetism,  opposite 
the  magnetic  equator,  its  south  pole  being  urged  along 
n  q,  and  its  north  along  n  p,  the  little  needle  will  be  com- 
pelled to  set  itself  parallel  to  the  magnet  s  N.  Make 
the  experiment,  and  satisfy  yourselves  that  this  is  a  true 
deduction. 

Substitute  for  your  magnetic  needle  a  bit  of  iron  wire, 
devoid  of  permanent  magnetism,  and  it  will  set  itself 
exactly  as  the  needle  does.  Acted  upon  by  the  magnet, 
the  wire,  as  you  know,  becomes  a  magnet  and  behaves  as 
such;  it  will  turn  its  north  pole  toward  p,  and  south  pole 
toward  q,  just  like  the  needle. 

But  supposing  you  shift  the  position  of  your  particle 
of  north  magnetism,  and  bring  it  nearer  to  one  end  of 


ELEMENTARY  MAGNETISM.  275 

your  magnet  than  to  the  other;  the  forces  acting  on  the 
particle  are  no  longer  equal;  the  nearest  pole  of  the 
magnet  will  act  more  powerfully  on  the  particle  than 
the  more  distant  one.  Let  s  N,  fig.  12,  be  the  magnet, 
and  n  the  particle  of  north  magnetism,  in  its  new  posi- 
tion. It  is  repelled  by  N,  and  attracted  by  s.  Let  the 
repulsion  be  represented  in  magnitude  and  direction  by 
the  line  n  o,  and  the  attraction  by  the  shorter  line  n  m. 
The  resultant  of  these  two  forces  will  be  found  by  com- 
pleting the  parallelogram  m  n  op,  and  drawing  its  diagonal 
np.  Along  np,  then,  a  particle  of  north  magnetism 
would  be  urged  by  the  simultaneous  action  of  s  and  N. 
Substituting  a  particle  of  south  magnetism  for  n,  the  same 
reasoning  would  lead  to  the  conclusion  that  the  particle 
would  be  urged  along  nq.  If  we  place  at  n  a  short  mag- 
netic needle,  its  north  pole  will  be  urged  along  n  p,  its 
south  pole  along  n  g,  the  only  position  possible  to  the 


S  I.' 


FIG.  12. 

needle,  thus  acted  on,  being  along  the  line  p  q,  which  is  no 
longer  parallel  to  the  magnet.  Verify  this  deduction  by 
actual  experiment. 

In  this  way  we  might  go  round  the  entire  magnet;  and, 
considering  its  two  poles  as  two  centers  from  which  the 
force  enamates,  we  could,  in  accordance  with  ordinary 
mechanical  principles,  assign  a  definite  direction  to  the 
magnetic  needle  at  every  particular  place.  And  substitut- 
ing, as  before,  a  bit  of  iron  wire  for  the  magnetic  needle, 
the  positions  of  both  will  be  the  same. 

Now,  I  think,  without  further  preface,  you  will  be  able 
to  comprehend  for  yourselves,  and  explain  to  others,  one  of 
the  most  interesting  effects  in  the  whole  domain  of 
magnetism.  Iron  filings  you  know  are  particles  of  iron, 
irregular  in  shape,  being  longer  in  some  directions  than  in 
others.  For  the  present  experiment,  moreover,  instead  of 


276  FRAGMENTS  OF  SCIENCE. 

the  iron  filings  very  small  scraps  of  thin  iron  wire  might 
be  employed.  I  place  a  sheet  of  paper  over  the  rnaguet; 
it  is  all  the  better  if  the  paper  be  stretched  on  a  wooden 
frame,  as  this  enables  us  to  keep  it  quite  level.  I  scatter 
the  filings,  or  the  scraps  of  wire,  from  a  sieve  upon  the 
paper,  and  tap  the  latter  gently,  so  as  to  liberate  the 
particles  for  a  moment  from  its  friction.  The  magnet  acts 
on  the  filings  through  the  paper,  and  see  how  it  arranges 
them!  They  embrace  the  magnet  in  a  series  of  beautiful 
curves,  which  are  technically  called  "magnetic  curves,"  or 
"  lines  of  magnetic  force."  Does  the  meaning  of  these 
lines  yet  flash  upon  you?  Set  your  magnetic  needle,  or 
your  suspended  bit  of  wire,  at  any  point  of  one  of  the 
curves,  and  you  will  find  the  direction  of  the  needle,  or  of 
the  wire,  to  be  exactly  that  of  the  particle  of  iron,  or  of 
the  magnetic  curve,  at  that  point.  Go  round  and  round 
the  magnet;  the  direction  of  your  needle  always  coincides 
with  the  direction  of  the  curve  on  which  it  is  placed. 
These,  then,  are  the  lines  along  which  a  particle  of  south 
magnetism,  if  you  could  detach  it,  would  move  to  the 
north  pole,  and  a  bit  of  north  magnetism  to  the  south 
pole.  They  are  the  lines  along  which  the  decomposition 
of  the  neutral  fluid  takes  place.  In  the  case  of  the  mag- 
netic needle,  one  of  its  poles  being  urged  in  one  direction, 
and  the  other  pole  in  the  opposite  direction,  the  needle 
must  necessarily  set  itself  as  a  tangent  to  the  curve.  I  will 
not  seek  to  simplify  this  subject  further.  If  there  be  any- 
thing obscure  or  confused  or  incomplete  in  my  statement, 
you  ought  now,  by  patient  thought,  to  be  able  to  clear 
away  the  obscurity,  to  reduce  the  confusion  to  order,  and 
to  supply  what  is  needed  to  render  the  explanation  com- 
plete. Do  not  quit  the  subject  until  you-  thoroughly 
understand  it;  and  if  you  are  then  able  to  look  with  your 
mind's  eye  at  the  play  of  forces  around  a  magnet,  and  see 
distinctly  the  operation  of  those  forces  in  the  production 
of  the  magnetic  curves,  the  time  which  we  have  spent 
together  will  not  have  been  spent  in  vain. 

In  this  thorough  manner  we  must  master  our  materials, 
reason  upon  them,  and,  by  determined  study,  attain  to 
clearness  of  conception.  Facts  thus  dealt  with  exercise  an 
expansive  force  upon  the  intellect — they  widen  the  mind 
to  generalization.  We  soon  recognize  a  brotherhood 
between  the  larger  phenomena  of  Nature  and  the  minute 


Fio.  13. 


277 


MAGNETIC    LINES  OF  FORCE. 
From  a  Photograph  by  PROFESSOR  JU? 


278  FRAGMENTS  OF  SCIENCE. 

effects  which  we  have  observed  in  our  private  chambers. 
Why,  we  inquire,  does  the  magnetic  needle  set  north  and 
south?  Evidently  it  is  compelled  to  do  so  by  the  earth; 
the  great  globe  which  we  inherit  is  itself  a  magnet.  Let  us 
learn  a  little  more  about  it.  By  means  of  a  bit  of  wax  or 
otherwise,  attach  the  end  of  your  silk  fiber  to  the  middle 
point  of  your  magnetic  needle;  the  needle  will  thus  be  un- 
interfered  with  by  the  paper  loop,  and  will  enjoy  to  some 
extent  a  power  of  "dipping"  its  point,  or  its  eye,  below 
the  horizon.  Lay  your  bar-magnet  on  a  table,  and  hold 
the  needle  over  the  equator  of  the  magnet.  The  needle 
sets  horizontal.  Move  it  toward  the  north  end  of  the 
magnet;  the  south  end  of  the  needle  dips,  the  dip  aug- 
menting as  you  approach  the  north  pole,  over  which  the 
needle,  if  free  to  move,  will  set  itself  exactly  vertical. 
Move  it  back  to  the  center,  it  resumes  its  horizontality; 
pass  it  on  toward  the  south  pole,  its  north  end  now  dips, 
and  directly  over  the  south  pole  the  needle  becomes  vertical, 
its  north  end  being  now  turned  downward.  Thus  we  learn 
that  on  the  one  side  of  the  magnetic  equator  the  north  end 
of  the  needle  dips;  on  the  other  side  the  south  end  dips, 
the  dip  varying  from  nothing  to  ninety  degrees.  If  we  go 
to  the  equatorial  regions  of  the  earth  with  a  suitably  sus- 
pended needle  we  shall  find  there  the  position  of  the  needle 
horizontal.  If  we  sail  north  one  end  of  the  needle  dips;  if 
we  sail  south  the  opposite  end  dips;  and  over  the  north  or 
south  terrestrial  magnetic  pole  the  needle  sets  vertical.  The 
south  magnetic  pole  has  not  yet  been  found,  but  Sir  James 
Ross  discovered  the  north  magnetic  pole  on  June  1,  1831. 
In  this  manner  we  establish  a  complete  parallelism  between 
the  action  of  the  earth  and  that  of  an  ordinary  magnet. 

The  terrestrial  magnetic  poles  do  not  coincide  with  the 
geographical  ones;  nor  does  the  earth's  magnetic  equator 
quite  coincide  with  the  geographical  equator.  The  direc- 
tion of  the  magnetic  needle  in  London,  which  is  called  the 
magnetic  meridian,  encloses  an  angle  of  24  degrees  with 
the  astronomical  meridian,  this  angle  being  called  the 
Declination  of  the  needle  for  London.  The  north  pole  of 
the  needle  now  lies  to  the  west  of  the  true  meridian;  the 
declination  is  westerly.  In  the  year  1660,  however,  the 
declination  was  nothing,  while  before  that  time  it  was 
easterly.  All  this  proves  that  the  earth's  magnetic  con- 
stituents are  gradually  changing  their  distribution.  This 


ELEMENTARY  MAGNETISM.  279 

change  is  very  slow:  it  is  therefore  called  the  secular 
change,  and  the  observation  of  it  has  not  yet  extended  over 
a  sufficient  period  to  enable  us  to  guess,  even  approximately, 
at  its  laws. 

Having  thus  discovered,  to  some  extent,  the  secret  of 
the  earth's  magnetic  power,  we  can  turn  it  to  account.  In 
the  line  of  "  dip"  I  hold  a  poker  formed  of  good  soft  iron. 
The  earth,  acting  as  a  magnet,  is  at  this  moment  con- 
straining the  two  fluids  of  the  poker  to  separate,  making 
the  lower  end  of  the  poker  a  north  pole,  and  the  upper  end 
a  south  pole.  Mark  the  experiment:  When  the  knob  is 
uppermost,  it  attracts  the  north  end  of  a  magnetic  needle; 
when  undermost  it  attracts  the  south  end  of  a  magnetic 
needle.  With  such  a  poker  repeat  this  experiment  and 
satisfy  yourselves  that  the  fluids  shift  their  position  accord- 
ing to  the  manner  in  which  the  poker  is  presented  to  the 
earth.  It  has  already  been  stated  that  the  softest  iron 
possesses  a  certain  amount  of  coercive  force.  The  earth, 
at  this  moment,  finds  in  this  force  an  antagonist  which 
opposes  the  decomposition  of  the  neutral  fluid.  The  com- 
ponent fluids  may  be  figured  as  meeting  an  amount  of 
friction,  or  possessing  an  amount  of  adhesion,  which 
prevents  them  from  gliding  over  the  molecules  of  the  poker. 
Can  we  assist  the  earth  in  this  case?  If  we  wish  to  remove 
the  residue  of  a  powder  from  the  interior  surface  of  a  glass 
to  which  the  powder  clings,  we  invert  the  glass,  tap  it, 
loosen  the  hold  of  the  powder,  and  thus  enable  the  force  of 
gravity  to  pull  it  down.  So  also  by  tapping  the  end  of  the 
poker  we  loosen  the  adhesion  of  the  magnetic  fluids  to  the 
molecules  .and  enable  the  earth  to  pull  them  apart.  But, 
what  is  the  consequence?  The  portion  of  fluid  which  has 
been  thus  forcibly  dragged  over  the  molecules  refuses  to 
return  when  the  poker  has  been  removed  from  the  line  of 
dip;  the  iron,  as  you  see,  has  become  a  permanent  magnet. 
By  reversing  its  position  and  tapping  it  again  we  reverse 
its  magnetism.  A  thoughtful  and  competent  teacher  will 
know  how  to  place  these  remarkable  facts  before  his  pupils 
in  a  manner  which  will  excite  their  interest.  By  the  use 
of  sensible  images,  more  or  less  gross,  he  will  first  give 
those  whom  he  teaches  definite  conceptions,  purifying 
these  conceptions  afterward,  as  the  minds  of  his  pupils 
become  more  capable  of  abstraction.  By  thus  giving 
them  a  distinct  substratum  for  their  reasonings,  he  will 


280  FRAGMENTS  OF  SCIENCE. 

confer  upon  his  pupils  a  profit  and  a  joy  which  the  mere 
exhibition  of  facts  without  principles,  or  the  appeal  to  the 
bodily  senses  and  the  power  of  memory  alone,  could  never 
inspire. 


As  an  expansion  of  the  note  at  p.  272,  the  following  extract  may 
find  a  place  here: 

"It  is  well  known  that  a  voltaic  current  exerts  an  attractive  force 
upon  a  second  current,  flowing  in  the  same  direction;  and  that  when 
the  directions  are  opposed  to  each  other  the  force  exerted  is  a  repul- 
sive one.  By  coiling  wires  into  spirals,  Ampere  was  enabled  to  make 
them  produce  all  the  phenomena  of  attraction  and  repulsion  exhibited 
by  magnets,  and  from  this  it  was  but  a  step  to  his  celebrated  theory 
of  molecular  currents.  He  supposed  the  molecules  of  a  magnetic 
body  to  be  surrounded  by  such  currents,  which,  however,  in  the 
natural  state  of  the  body  mutually  neutralized  each  other,  on  account 
of  their  confused  grouping.  The  act  of  magnetization  he  supposed 
to  consist  in  setting  these  molecular  currents  parallel  to  each  other; 
and,  starting  from  this  principle,  he  reduced  all  the  phenomena  of 
magnetism  to  the  mutual  action  of  electric  currents.  - 

"If  we  reflect  upon  the  experiments  recorded  in  the  foregoing 
pages  from  first  to  last,  we  can  hardly  fail  to  be  convinced  that  dia- 
magnetic  bodies  operated  on  by  magnetic  forces  possess  a  polarity 
'  the  same  in  kind  as,  but  the  reverse  in  direction  of  that  acquired  by 
magnetic  bodies.'  But  if  this  be  the  case,  how  are  we  to  conceive  the 
physical  mechanism  of  this  polarity?  According  to  Coulomb's  and 
Poisson's  theory,  the  act  of  magnetization  consists  in  the  decomposi- 
tion of  a  neutral  magnetic  fluid;  the  north  pole  of  a  magnet,  for 
example,  possesses  an  attraction  for  the  south  fluid  of  a  piece  of  soft 
iron  submitted  to  its  influence,  draws  the  said  fluid  toward  it,  and 
with  it  the  material  particles  with  which  the  fluid  is  associated.  To 
account  for  diamagnetic  phenomena  this  theory  seems  to  fail  altogether; 
according  to  it,  indeed,  the  oft-used  phrase,  '  a  north  pole  exciting  a 
north  pole,  and  a  south  pole  a  south  pole,'  involves  a  contradiction. 
For  if  the  north  fluid  be  supposed  to  be  attracted  toward* the  influenc- 
ing north  pole,  it  is  absurd  to  suppose  that  its  presence  there  could 
produce  repulsion.  The  theory  of  Ampere  is  equally  at  a  loss  to 
explain  diamagnetic  action;  for  if  we  suppose  the  particles  of  bismuth 
surrounded  by  molecular  currents,  then,  according  to  all  that  is 
known  of  electro-dynamic  laws,  these  currents  would  set  themselves 
parallel  to,  and  in  the  same  direction  as  those  of  the. magnet,  and 
hence  attraction,  and  not  repulsion,  would  be  the  result.  The  fact, 
however,  of  this  not  being  the  case,  proves  that  these  molecular  cur- 
rents are  not  the  mechanism  by  which  diamagnetic  induction  is 
effected.  The  consciousness  of  this,  I  doubt  not,  drove  M.  Weber  to 
the  assumption  that  the  phenomena  of  diamagnetism  are  produced 
by  molecular  currents,  not  directed,  but  actually  excited  in  the  bismuth 
by  the  magnet.  Such  induced  currents  would,  according  to  known 
laws,  have  a  direction  opposed  to  those  of  the  inducing  magnet; 
a»d  hence  would  produce  the  phenomena  of  repulsion.  To  carry 


ON  FORCE.  281 

out  the  assumption  here  made,  M.  Weber  is  obliged  to  suppose  that 
the  molecules  of  diamagnetic  bodies  are  surrounded  by  channels, 
in  which  the  induced  molecular  currents,  once  excited,  continue 
to  flow  without  resistance."* — Diamagnetism  and  Magne-crystallic 
Action,  p.  136-7. 


CHAPTER  XVI. 

ON   FORCE,  f 

A  SPHERE  of  lead  was  suspended  at  a  height  of  16  feet 
above  the  theater  floor  of  the  Royal  Institution.  It  was 
liberated,  and  fell  by  gravity.  That  weight  required  a 
second  to  fall  to  the  floor  from  that  elevation;  and  the 
instant  before  it  touched  the  floor  it  had  a  velocity  of  32 
feet  a  second.  That  is  to  say,  if  at  that  instant  the  earth 
were  annihilated,  and  its  attraction  annulled,  the  weight 
would  proceed  through  space  at  the  uniform  velocity  of  32 
feet  a  second. 

If  instead  of  being  pulled  downward  by  gravity,  the 
weight  be  cast  upward  in  opposition  to  gravity,  then,  to 
reach  a  height  of  16  feet  it  must  start  with  a  velocity  of  32 
feet  a  second.  This  velocity  imparted  to  the  weight  by 
the  human  hand,  or  by  any  other  mechanical  means,  would 
carry  it  to  the  precise  height  from  which  we  saw  it  fall. 

Now  the  lifting  of  the  weight  may  be  regarded  as  so 
much  mechanical  work  performed.  By  means  of  a  ladder 
placed  against  the  wall,  the  weight  might  be  carried  up  to 
a  height  of  16  feet;  or  it  might  be  drawn  up  to  this  height 
by  means  of  a  string  and  pulley,  or  it  might  be  suddenly 
jerked  up  to  a  heiglit  of  16  feet.  The  amount  of  work 
done  in  all  these  cases,  as  far  as  the  raising  of  the  weight 
is  concerned,  would  be  absolutely  the  same.  The  work 
done  at  one  and  the  same  place,  and  neglecting  the  small 
change  of  gravity  with  the  height,  depends  solely  upon  two 
things;  on  the  quantity  of  matter  lifted,  and  on  the  height 
to  which  it  is  lifted.  If  we  call  the  quantity  or  mass  of 
matter  m,  and  the  height  through  which  it  is  lifted  h,  then 
the  product  of  m.  into  h,  or  m  h,  expresses,  or  is  propor- 
tional to  the  amount  of  work  done. 

Supposing,  instead  of  imparting  a  velocity  of  32  feet  a 

*  In  assuming  these  non-resisting  channels  M.  Weber,  it  must  be 
admitted,  did  not  go  beyond  the  assumptions  of  Ampere. 

•j- A  discourse  delivered  in  the  Royal  Institution,  June  6,  1863. 


282  -  FRAGMENTS  OF  SCIENCE. 

second  we  impart  at  starting  twice  this  velocity.  To  what 
height  will  the  weight  rise?  You  might  be  disposed  to 
answer,  "  To  twice  the  height?"  but  this  would  be  quite 
incorrect.  Instead  of  twice  16,  or  32  feet,  it  would  reach 
a  height  of  four  times  16,  or  64  feet.  So  also,  if  we  treble 
the  starting  velocity,  the  weight  would  reach  nine  times 
the  height;  if  we  quadruple  the  speed  at  starting,  we  attain 
sixteen  times  the  height.  Thus,  with  a  fourfold  velocity 
of  128  feet  a  second  at  starting,  the  weight  would  attain  an 
elevation  of  256  feet.  With  a  sevenfold  velocity  at  start- 
ing, the  weight  would  rise  to  49  times  the  height,  or  to  an 
elevation  of  784  feet. 

Now  the  work  done — or,  as  it  is  sometimes  called,  the 
mechanical  effect — other  things  being  constant,  is,  as  before 
explained,  proportional  to  the  height,  and  as  a  double 
velocity  gives  four  times  the  height,  a  treble  velocity  nine 
times  the  height,  and  so  on,  it  is  perfectly  plain  that  the 
mechanical  effect  increases  as  the  square  of  the  velocity. 
If  the  mass  of  the  body  be  represented  by  the  letter  m,  and 
its  velocity  by  v,  the  mechanical  effect  would  be  propor- 
tional to  or  represented  by  m  vz.  In  the  case  considered, 
I  have  supposed  the  weight  to  be  cast  upward,  being 
opposed  in  its  flight  by  the  resistance  of  gravity;  but  the 
same  holds  true  if  the  projectile  be  sent  into  water,  mud, 
earth,  timber,  or  other  resisting  material.  If,  for  example, 
we  double  the  velocity  of  a  cannon  ball  we  quadruple  its 
mechanical  effect.  Hence  the  importance  of  augmenting 
the  velocity  of  a  projectile,  and  hence  the  philosophy  of 
Sir  William  Armstrong  in  using  a  large  charge  of  powder 
in  his  recent  striking  experiments. 

The  measure  then  of  mechanical  effect  is  the  mass  of  the 
body  multiplied  by  the  square  of  its  velocity. 

Now  in  firing  a  ball  against  a  target  the  projectile,  after 
collision,  is  often  found  hot.  Mr.  Fairbairn  informs  me 
that  in  the  experiments  at  Shoeburyness  it  is  a  common 
thing  to  see  a  flash,  even  in  broad  daylight,  when  the  ball 
strikes  the  target.  And  if  our  lead  weight  be  examined 
after  it  has  fallen  from  a  height  it  is  also  found  heated. 
Now  here  experiment  and  reasoning  lead  us  to  the  remark- 
able law  that,  like  the  mechanical  effect,  the  amount  of 
he-it  generated  is  proportional  to  the  product  of  the  mass 
into  the  square  of  the  velocity.  Double  your  mass,  other 
things  being  equal,  and  you  double  your  amount  of  heutj 


OX  FORCE.  283 

double  your  velocity,  other  things  remaining  equal,  and 
you  quadruple  your  amount  of  heat.  Here  then  we  have 
common  mechanical  motion  destroyed  and  heat  produced. 
When  a  violin  bow  is  drawn  across  a  string,  the  sound 
produced  is  due  to  motion  imparted  to  the  air,  and  to 
produce  that  motion  muscular  force  has  been  expended. 
We  may  here  correctly  say,  that  the  mechanical  force  of 
the  a*rm  is  converted  into  music.  In  a  similar  way  we  say 
that  the  arrested  motion  of  our  descending  weight,  or  of 
the  cannon  ball,  is  converted  into  heat.  The  mode  of 
motion  changes,  but  motion  still  continues;  the  motion  of 
the  mass  is  converted  into  a  motion  of  the  atoms  of  the 
mass;  and  these  small  motions,  communicated  to  the 
nerves,  produce  the  sensation  we  call  heat. 

AVe  know  the  amount  of  heat  which  a  given  amount  of 
mechanical  force  can  develop.  Our  lead  ball,  for  ex- 
ample, in  falling  to  the  earth  generated  a  quantity  of  heat 
sufficient  to  raise  its  own  temperature  three-fifths  of  a 
Fahrenheit  degree.  It  reached  the  earth  with  a  velocity 
of  82  feet  a  second,  and  forty  times  this  velocity  would  be 
small  for  a  rifle  bullet;  multiplying  three-fifths  by  the 
square  of  40,  we  find  that  the  amount  of  heat  developed  by 
collision  with  the  target  would,  if  wholly  concentrated  in 
the  lead,  raise  its  temperature  960  degrees.  This  would  be 
more  than  sufficient  to  fuse  the  lead.  In  reality,  however, 
the  heat  developed  is  divided  between  the  lead  and  the 
body  against  which  it  strikes;  nevertheless,  it  would  be 
worth  while  to  pay  attention  to  this  point,  and  to  ascertain 
whether  rifle  bullets  do  not,  under  some  circumstances, 
show  signs  of  fusion.* 

From  the  motion  of  sensible  masses,  by  gravity  and 
other  means,  we  now  pass  to  the  motion  of  atoms  toward 
each  other  by  chemical  affinity.  A  collodion  balloon  filled 
with  a  mixture  of  chlorine  and  hydrogen  being  hung  in 
the  focus  of  a  parabolic  mirror,  in  the  focus  of  a  second 
mirror  20  feet  distant  a  strong  electric  light  was  sud- 
denly generated;  the  instant  the  concentrated  light  fell 
upon  the  balloon,  the  gases  within  it  exploded,  hydro- 
chloric acid  being  the  result.  Here  the  atoms  virtually  fell 
together,  the  amount  of  heat  produced  showing  the 

*  Eight  years  subsequently  this  surmise  was  proved  correct.  In 
the  Franco- German  War  signs  of  fusion  were  observed  in  the  case  of 
bullets  impinging  on  bones. 


284.  FRAGMENTS  OF  SCIENCE. 

enormous  force  of  the  collision.  The  burning  of  charcoal 
in  oxygen  is  an  old  experiment,  but  it  has  now  a  signifi- 
cance beyond  what  it  used  to  have;  we  now  regard  the  act 
of  combination  on  the  part  of  the  atoms  of  oxygen  and 
coal  as  we  regard  the  clashing  of  a  falling  weight  against 
the  earth.  The  heat  produced  in  both  cases  is  referable  to 
a  common  cause.  A  diamond,  which  burns  in  oxygen  as  a 
star  of  white  light,  glows  and  burns  in  consequence  of  the 
falling  of  the  atoms  of  oxygen  against  it.  And  could  we 
measure  the  velocity  of  the  atoms  when  they  clash,  and 
could  we  find  their  number  and  weights,  multiplying  the 
weight  of  each  atom  by  the  square  of  its  velocity,  and  add- 
ing all  together,  we  should  get  a  number  representing  the 
exact  amount  of  heat  developed  by  the  union  of  the  oxygen 
and  carbon. 

Thus  far  we  have  regarded  the  heat  developed  by  the 
clashing  of  sensible  masses  and  of  atoms.  Work  is  ex- 
pended in  giving  motion  to  these  atoms  or  masses,  and  heat 
is  developed.  But  we  reverse  this  process  daily,  and  by 
the  expenditure  of  heat  execute  work.  We  can  raise  a 
weight  by  heat;  and  in  this  agent  we  possess  an  enormous 
store  of  mechanical  power.  A  pound  of  coal  produces  by 
its  combination  with  oxygen  an  amount  of  heat  which,  if 
mechanically  applied,  would  suffice  to  raise  a  weight  of 
100  Ibs.  to  a  height  of  20  miles  above  the  earth's  surface. 
Conversely,  100  Ibs.  falling  from  a  height  of  20  miles,  and 
striking  against  the  earth,  would  generate  an  amount  of 
heat  equal  to  that  developed  by  the  combustion  of  a  pound 
of  coal.  Wherever  work  is  done  by  heat,  heat  disappears. 
A  gun  which  fires  a  ball  is  less  heated  than  one  which  fires 
blank  cartridge.  The  quantity  of  heat  communicated  to 
the  boiler  of  a  working  steam-engine  is  greater  than  that 
which  could  be  obtained  from  the  re-condensation  of  the 
steam,  after  it  had  done  its  work;  and  the  amount  of  work 
performed  is  the  exact  equivalent  of  the  amount  of  heat 
lost.  Mr.  Smyth  informed  us  in  his  interesting  discourse, 
that  we  dig  annually  84  millions  of  tons  of  coal  from  our 
pits.  The  amount  of  mechanical  force  represented  by  this 
quantity  of  coal  seems  perfectly  fabulous.  The  combustion 
of  a  single  pound  of  coal,  supposing  it  to  take  place  in  a 
minute,  would  be  equivalent  to  the  work  of  300  horses; 
and  if  we  suppose  108  millions  of  horses  working  day  and 
night  with  unimpaired  strength,  for  a  year,  their  united. 


ON  FORCE.  285 

energies  would  enable  them  to  perform  an  amount  of  work 
just  equivalent  to  that  which  the  annual  produce  of  our 
coal-fields  would  be  able  to  accomplish. 

Comparing  with  ordinary  gravity  the  force  with  which 
oxygen  and  carbon  unite  together,  chemical  affinity  seems 
almost  infinite.  But  let  us  give  gravity  fair  play  by  per- 
mitting it  to  act  throughout  its  entire  range.  Place  a  body 
at  such  a  distance  from  the  earth  that  the  attraction  of  our 
planet  is  barely  sensible,  and  let  it  fall  to  the  earth  from 
this  distance.  It  would  reach  the  earth  with  a  final  ve- 
locity of  36,747  feet  a  second;  and  on  collision  with  the 
earth  the  body  would  generate  about  twice  the  amount  of 
heat  generated  by  the  combustion  of  an  equal  weight  of 
coal.  We  have  stated  that  by  falling  through  a  space  of 
16  feet  our  lead  bullet  would  be  heated  three-fifths  of  a 
degree;  but  a  body  falling  from  an  infinite  distance  has  al- 
ready used  up  1,299,999  parts  out  of  1,300,000  of  the  earth's 
pulling  power,  when  it  has  arrived  within  16  feet  of  the 
surface;  on  this  space  only  one  one  million  three  hundred 
thousandths  of  the  whole  force  is  exerted. 

Let  us  now  turn  our  thoughts  for  a  moment  from  the 
earth  to  the  sun.  The  researches  of  Sir  John  Herschel  and 
M.  Pouillet  have  informed  us  of  the  annual  expenditure  of 
the  sun  as  regards  heat;  and  by  an  easy  calculation 
we  ascertain  the  precise  amount  of  the  expendi- 
ture which  falls  to  the  share  of  our  planet.  Out 
of  2,300  million  parts  of  light  and  heat  the  earth 
receives  one.  The  whole  heat  emitted  by  the  sun  in  a 
minute  would  be  competent  to  boil  12,000  millions  of 
cubic  miles  of  ice-cold  water.  How  is  this  enormous  loss 
made  good — whence  is  the  sun's  heat  derived,  and  by  what 
means  is  it  maintained?  No  combustion — no  chemical 
affinity  with  which  we  are  acquainted,  would  be  competent 
to  produce  the  temperature  of  the  sun's  surface.  Besides, 
were  the  sun  a  burning  body  merely,  its  light  and  heat 
would  speedily  come  to  an  end.  Supposing  it  to  be  a  solid 
globe  of  coal,  its  combustion  would  only  cover  4,600  years 
of  expenditure.  In  this  short  time  it  would  burn  itself 
out.  What  agency  then  can  produce  the  temperature  and 
maintain  the  outlay?  We  have  already  regarded  the  case 
of  a  body  falling  from  a  great  distance  toward  the  earth 
and  found  that  the  heat  generated  by  its  collision  would  be 
twice  that  produced  by  the  combustion  of  an  equal  weight 


286  FRAGMENTS  OF  SCIENCE. 

of  coal.  How  much  greater  must  be  the  heat  developed  by 
a  body  falling  against  the  sun!  The  maximum  velocity 
with  which  a  body  can  strike  the  earth  is  about  seven  miles 
in  a  second;  the  maximum  velocity  with  which  it  can 
strike  the  sun  is  390  miles  in  a  second.  And  as  the  heat 
developed  by  the  collision  is  proportional  to  the  square  of 
the  velocity  destroyed,  an  asteroid  falling  into  the  sun 
with  the  above  velocity  would  generate  about  10,000  times 
the  quantity  of  heat  produced  by  the  combustion  of  an 
asteroid  of  coal  of  the  same  weight. 

Have  we  any  reason  to  believe  that  such  bodies  exist  in 
space,  and  that  they  may  be  raining  down  upon  the  sun? 
The  meteorites  flashing  through  the  air  are  small  planet- 
ary bodies,  drawn  by  the  earth's  attraction.  They  enter 
our  atmosphere  with  planetary  velocity,  and  by  friction 
against  the  air  they  are  raised  to  incandescence  and  caused 
to  emit  light  and  heat.  At  certain  seasons  of  the  year 
they  shower  down  upon  us  in  great  numbers.  In  Boston 
240,000  of  them  were  observed  in  nine  hours.  There  is 
no  reason  to  suppose  that  the  planetary  system  is  limited 
to  "  vast  masses  of  enormous  weight;"  there  is,  on  the  con- 
trary, reason  to  believe  that  space  is  stocked  with  smaller 
masses,  which  obey  the  same  laws  as  the  larger  ones.  That 
lenticular  envelope  which  surrounds  the  sun,  and  which  is 
known  to  astronomers  as  the  Zodiacal  light,  is  probably  a 
crowd  of  meteors;  and  moving  as  they  do  in  a  resisting 
medium,  they  must  continually  approach  the  sun.  Falling 
into  it,  they  would  produce  enormous  heat,  and  this 
would  constitute  a  source  from  which  the  annual 
loss  of  heat  might  be  made  good.  The  sun,  according 
to  this  hypothesis,  would  continually  grow  larger;  but 
how  much  larger?  Were  our  moon  to  fall  into  the 
sun,  it  would  develop  an  amount  of  heat  sufficient  to 
cover  one  or  two  years'  loss;  and  were  our  earth  to 
fall  into  the  sun  a  century's  loss  would  be  made  good. 
Still,  our  moon  and  our  earth,  if  distributed  over  the  sur- 
face of  the  sun,  would  utterly  vanish  from  perception. 
Indeed,  the  quantity  of  matter  competent  to  produce  the 
required  effect,  would,  during  the  range  of  history,  cause 
no  appreciable  augmentation  in  the  sun's  magnitude.  The 
augmentation  of  the  sun's  attractive  force  would  be  more 
sensible.  However  this  hypothesis  may  fare  as  a  repre- 
sentant  of  what  is  going  on  in  nature,  it  certainly  shows 


ON  FORCE.  287 

lio\v  a  sun  might  be  formed  and  maintained  on  known 
thermo-dynamic  principles. 

Our  earth  moves  in  its  orbit  with  a  -velocity  of 
68,040  miles  an  hour.  Were  this  motion  stopped,  an 
amount  of  heat  would  be  developed  sufficient  to  raise  the 
temperature  of  a  globe  of  lead  of  the  same  size  as  the 
earth  384,000  degrees  of  the  centigrade  thermometer. 
It  has  been  prophesied  that  "  the  elements  shall  melt  with 
fervent  heat."  The  earth's  own  motion  embraces  the  con- 
ditions of  fulfillment;  stop  that  motion  and  the  greater 
part,  if  not  the  whole,  of  our  planet  would  be  reduced  to 
vapor.  Jf  the  earth  fell  into  the  sun,  the  amount  of  heat 
developed  by  the  shock  would  be  equal  to  that  developed 
by  the  combustion  of  a  mass  of  solid  coal  6,435  times  the 
earth  in  size. 

There  is  one  other  consideration  connected  with  the  per- 
manence of  our  present  terrestrial  conditions,  which  is 
well  worthy  of  our  attention.  Standing  upon  one  of  the 
London  bridges,  we  observe  the  current  of  the  Thames 
reversed,  and  the  water  poured  upward  twice  a  day.  The 
water  thus  moved  rubs  against  the  river's  bed,  and  heat  is 
the  consequence  of  this  friction.  The  heat  thus  generated 
is  in  part  radiated  into  space  and  lost,  as  far  as  the  earth  is 
concerned.  What  supplies  this  incessant  loss?  The  earth's 
rotation.  Let  us  look  a  little  more  closely  at  the  matter. 
Imagine  the  moon  fixed,  and  the  earth  turning  like  a 
wheel  from  west  to  east  in  its  diurnal  rotation.  Suppose  a 
high  mountain  on  the  earth's  surface  approaching  the 
earth's  meridian;  that  mountain  is,  as  it  were,  laid  hold  of 
by  the  moon;  it  forms  a  kind  of  handle  by  which  the  earth 
is  pulled  more  quickly  round.  But  when  the  meridian  is 
passed  the  pull  of  the  moon  on  the  mountain  would  be  in 
the  opposite  direction,  it  would  tend  to  diminish  the  ve- 
locity of  rotation  as  much  as  it  previously  augmented  it; 
thus  the  action  of  all  fixed  bodies  on  the  earth's  surface  is 
neutralized.  But  suppose  the  mountain  to  lie  always  to  the 
east  of  the  moon's  meridian,  the  pull  then  would  be  always 
exerted  against  the  earth's  rotation,  the  velocity,  of  which 
would  be  diminished  in  a  degree  corresponding  to  the 
strength  of  the  pull.  Tlie  tidal  wave  occupies  this  position 
— it  lies  always  to  the  east  of  the  moon's  meridian.  The 
waters  of  the  ocean  are  in  part  dragged  as  a  brake  along 
the  surface  of  the  earth;  and  as  a  brake  they  must  dimin- 


288  FRAGMENTS  OF  SCIENCE. 

ish  the  velocity  of  the  earth's  rotation.*  Supposing  then 
that  we  turn  a  mill  by  the  action  of  the  tide,  and  produce 
heat  by  the  friction  of  the  millstones;  that  heat  has  an 
origin  totally  different  from  the  heat  produced  by  another 
mill  which  is  turned  by  a  mountain  stream.  The  former- 
is  produced  at  the  expense  of  the  earth's  rotation,  the 
latter  at  the  expense  of  the  sun's  radiation. 

The  sun,  by.  the  act  of  vaporization,  lifts  mechanically 
all  the  moisture  of  our  air,  which  when  it  condenses  falls  in 
the  form  of  rain,  and  when  it  freezes  falls  as  snow.  In 
this  solid  form  it  is  piled  upon  the  Alpine  heights,  and  fur- 
nishes materials  for  glaciers.  But  the  sun  again  inter- 
poses, liberates  the  solidified  liquid,  and  permits  it  to  roll 
by  gravity  to  the  sea.  The  mechanical  force  of  every 
river  in  the  world  as  it  rolls  toward  the  ocean,  is  drawn 
from  the  heat  of  the  sun.  No  streamlet  glides  to  a  lower 
level  without  having  been  first  lifted  to  the  elevation  from 
which  it  springs  by  the  power  of  the  sun.  The  energy  of 
winds  is  also  due  entirely  to  the  same  power. 

But  there  is  still  another  work  which  the  sun  performs, 
and  its  connection  with  which  is  not  so  obvious.  Trees 
and  vegetables  grow  upon  the  earth,  and  when  burned 
they  give  rise  to  heat,  and  hence  to  mechanical  energy. 
Whence  is  this  power  derived?  You  see  this  oxide  of  iron, 
produced  by  the  falling  together  of  the  atoms  of  iron  and 
oxygen;  you  cannot  see  this  transparent  carbonic  acid  gas, 
formed  by  the  falling  together  of  carbon  and  oxygen. 
The  atoms  thus  in  close  union  resemble  our  lead  weight 
while  resting  on  the  earth;  but  we  can  wind  up  the  weight 
and  prepare  it  for  another  fall,  and  so  these  atoms  can  be 
wound  up  and  thus  enabled  to  repeat  the  process  of  com- 
bination. In  the  building  of  plants  carbonic  acid  is  the 
material  from  which  the  carbon  of  the  plant  is  derived; 
and  the  solar  beam  is  the  agent  which  tears  the  atoms 
asunder,  setting  the  oxygen  free,  and  allowing  the  carbon 
to  aggregate  in  woody  fiber.  Let  the  solar  rays  fall  upon  a 
surface  of  sand;  the  sand  is  heated,  and  finally  radiates 
away  as  much  heat  as  it  receives;  let  the  same  beams  fall 
upon  a  forest,  the  quantity  of  heat  given  back  is  less  than 
the  forest  receives;  for  the  energy  of  a  portion  of  the  sun- 
beams is  invested  in  building  the  trees.  Without  the  sun 

*  Kant  surmised  an  action  of  this  kind. 


ON  FORGE.  289 

the  reduction  of  the  carbonic  acid  cannot  be  effected,  and 
an  amount  of  sunlight  is  consumed  exactly  equivalent  to 
the  molecular  work  done.  Thus  trees  are  formed;  thus 
the  cotton  on  which  Mr.  Bazley  discoursed  last  Friday  is 
produced.  I  ignite  this  cotton,  and  it  flames;  the  oxygen 
again  unites  with  the  carbon;  but  an  amount  of  heat  equal 
to  that  produced  by  its  combustion  was  sacrificed  by  the 
sun  to  form  that  bit  of  cotton. 

We  cannot,  however,  stop  at  vegetable  life,  for  it  is  the 
source,  mediate  or  immediate,  of  all  animal  life.  The  sun 
severs  the  carbon  from  its  oxygen  and  builds  the  vegetable; 
the  animal  consumes  the  vegetable  thus  formed,  a  reunion 
of  the  severed  elements  takes  place,  producing  animal 
heat.  The  process  of  building  a  vegetable  is  one  of  wind- 
ing up;  the  process  of  building  an  animal  is  one  of  running 
down.  The  warmth  of  our  bodies,  and  every  mechanical 
energy  which  we  exert,  trace  their  lineage  directly  to  the 
sun.  The  fight  of  a  pair  of  pugilists,  the  motion  of  an 
army,  or  the  lifting  of  his  own  body  by  an  Alpine  climber 
up  a  mountain  slope,  are  all  cases  of  mechanical  energy 
drawn  from  the  sun.  A  man  weighing  150  pounds  has  64 
pounds  of  muscle;  but  these,  when  dried,  reduce  them- 
selves to  15  pounds.  Doing  an  ordinary  day's  work,  for 
eighty  days,  this  mass  of  muscle  would  be  wholly  oxidized. 
Special  organs  which  do  more  work  would  be  more  quickly 
consumed:  the  heart,  for  example,  if  entirely  unsustained, 
would  be  oxidized  in  about  a  week.  Take  the  amount  of 
heat  due  to  the  direct  oxidation  of  a  given  weight  of  food; 
less  heat  is  developed  by  the  oxidation  of  the  same  amount 
of  food  in  the  working  animal  frame,  and  the  missing 
quantity  is  the  equivalent  of  the  mechanical  work  accom- 
plished by  the  muscles. 

I  might  extend  these  considerations;  the  work,  indeed, 
is  done  to  rny  hand — but  I  am  warned  that  you  have  been 
already  kept  too  long.  To  whom  then  are  we  indebted  for 
the  most  striking  generalizations  of  this  evening's  dis- 
course? They  are  the  work  of  a  man  of  whom  you  have 
scarcely  ever  heard — the  published  labors  of  a  German 
doctor,  named  Mayer.  Without  external  stimulus,  and 
pursuing  his  profession  as  town  physician  in  Heilbronn, 
this  man  was  the  first  to  raise  the  conception  of  the 
interaction  of  heat  and  other  natural  forces  to  clearness  in 
his  own  mind.  And  yet  he  is  scarcely  ever  heard  of,  and 


290  FRAGMENTS  OF  SCIENCE. 

even  to  scientific  men  his  merits  are  but  partially  known. 
Led  by  his  own  beautiful  researches,  and  quite  independ- 
ent of  Mayer,  Mr.  Joule  published  in  1843  his  first  paper 
on  the  "  Mechanical  Value  of  Heat;"  but  in  1842  Mayer 
had  actually  calculated  the  mechanical  equivalent  of  heat 
from  data  which  only  a  man  of  the  rarest  penetration  could 
turn  to  account.  In  1845  he  published  his  memoir  on 
"  Organic  Motion,"  and  applied  the  mechanical  theory  of 
heat  in  the  most  fearless  and  precise  manner  to  vital 
processes.  He  also  embraced  the  other  natural  agents  in 
his  chain  of  conservation.  In  1853  Mr.  Waterston  pro- 
posed, independently,  the  meteoric  theory  of  the  sun's  heat, 
and  in  1854  Professor  William  Thomson  applied  his 
admirable  mathematical  powers  to  the  development  of  the 
theory;  but  six  years  previously  the  subject  had  been 
handled  in  a  masterly  manner  by  Mayer,  and  all  that  I 
have  said  about  it  has  been  derived  from  him.  When  we 
consider  the  circumstances  of  Mayer's  life,  and  the  period 
at  which  he  wrote,  we  cannot  fail  to  be  struck  with 
astonishment  at  what  he  has  accomplished.  Here  was  a 
man  of  genius  working  in  silence,  animated  solely  by  a  love 
of  his  subject,  and  arriving  at  the  most  important  results 
in  advance  of  those  whose  lives  were  entirely  devoted  to 
natural  philosophy.  It  was  the  accident  of  bleeding  a 
feverish  patient  at  Java  in  1840  that  led  Mayer  to  speculate 
on  these  subjects.  He  noticed  that  the  venous  blood  in 
the  tropics  was  of  a  brighter  red  than  in  colder  latitudes, 
and  his  reasoning  on  this  fact  led  him  into  the  laboratory 
of  natural  forces,  where  he  has  worked  with  such  signal 
ability  and  success.  Well,  you  will  desire  to  know  what 
has  become  of  this"  man.  His  mind,  it  is  alleged,  gave 
way;  it  is  said  he  became  insane,  and  he  was  certainly  sent 
to  a  lunatic  asylum.  In  a  biographical  dictionary  of  his 
country  it  is  stated  that  he  died  there,  but  this  is  incorrect. 
He  recovered;  and,  I  believe,  is  at  this  moment  a  cultivator 
of  vineyards  in  Heilbronn. 


June  20,  1862. 

While  preparing  for  publication  my  last  course  of  lectures 
on  Heat,  I  wished  to  make  myself  acquainted  with  all  that 
Dr.  Mayer  had  done  in  connection  with  this  subject.  I 
accordingly  wrote  to  two  gentlemen  who  above  all  others 


ON  FORCE.  291 

seemed  likely  to  give '  me  the  information  which  I 
needed.*  Both  of  them  are  Germans,  and  both  particu- 
larly distinguished  in  connection  with  the  Dynamical 
Theory  of  Heat.  Each  of  them  kindly  furnished  me  with 
the  list  of  Mayer's  publications,  and  one  of  them  [Clausins] 
was  so  friendly  as  to  order  them  from  a  bookseller,  and  to 
send  them  to  me.  This  friend,  in  his  reply  to  my  first 
letter  regarding  Mayer,  stated  his  belief  that  I  should  not 
find  anything  very  important  in  Mayers  writings;  but  be- 
fore forwarding  the  memoirs  to  me  he  read  them  himself. 
His  letter  accompanying  them  contains  the  following  words: 
'•'  I  must  here  retract  the  statement  in  my  last  letter,  that 
you  would  not  find  much  matter  of  importance  in  Mayer's 
writings:  I  am  astonished  at  the  multitude  of  beautiful 
and  correct  thoughts  which  they  contain;  "  and  he  goes  on 
to  point  out  various  important  subjects,  in  the  treatment 
of  which  Mayer  had  anticipated  other  eminent  writers. 
My  other  friend,  in  whose  own  publications  the  name  of 
Mayer  repeatedly  occurs,  and  whose  papers  containing 
these  references  were  translated  some  years  ago  by  myself, 
was,  on  the  10th  of  last  month,  unacquainted  with  the 
thoughtful  and  beautiful  essay  of  Mayer's,  entitled  "  Bei- 
trage  zur  Dynamik  des  Himrnels,"  and  in  1854,  when  Pro- 
fessor William  Thomson  developed  in  so  striking  a  manner 
the  meteoric  theory  of  the  sun's  heat,  he  was  certainly  not 
aware  of  the  existence  of  that  essay,  though  from  a  recent 
article  in  "  Macmillan's  Magazine  "  I  infer  that  he  is  now 
aware  of  it.  Mayer's  physiological  writings  have  been  re- 
ferred to  by  physiologists — by  Dr.  Carpenter,  for  example 
— in  terms  of  honoring  recognition.  We  have  hitherto,  in- 
deed, obtained  fragmentary  glimpses  of  the  man  partly  from 
physicists  and  partly  from  physiologists;  but  his  total  merit 
has  never  yet  been  recognized  as  it  assuredly  would  have 
been  had  he  chosen  a  happier  mode  of  publication.  I  do 
not  think  a  greater  disservice  could  be  done  to  a  man  of 
science,  than  to  overstate  his  claims:  such  overstatement  is 
sure  to  recoil  to  the  disadvantage  of  him  in  whose  interest 
it  is  made.  But  when  Mayer's  opportunities,  achievements, 
and  fate  are  taken  into  account,  I  do  not  think  that  I  shall 
be  deeply  blamed  for  attempting  to  place  him  in  that 
honorable  position,  which  I  believe  to  be  his  due. 

*  HeltuLoltz  and  Clausius. 


292  fBA  OMENT8  OF  SCIENCE. 

Here,  however,  are  the  titles  of  Mayer's  papers,  the 
perusal  of  which  will  correct  any  error  of  judgment  into 
which  I  may  have  fallen  regarding  their  author.  "Be- 
merkungen  iiber  die  Krafte  der  unbelebten  Natur,"  Lie- 
big's  " Annalen,"  1842,  Vol.  42,  p.  231;  "Die  Organische 
Bewegung  in  ihrem  Zusamtnenhange  mit  dem  Stoffwech- 
sel/'  Heilbronn,  1845;  "Beitrage  zur  Dynamik  des  Him- 
rnels,"  Heilbronn,  1848;  "  Bemerkungen  fiber  das 
Mechanische  Equivalent  der  Warme,"  Heilbronn,  1851. 


IN  MEMOBIAM.— Dr.  Julius  Robert  Mayer  died  at  Heil- 
broun  on  March  20,  1878,  aged  63  years.  It  gives  me 
pleasure  to  reflect  that  the  great  position  which  he  will  for- 
ever occupy  in  the  annals  of  science  was  first  virtually  as- 
signed to  him  in  the  foregoing  discourse.  He  was  subse- 
quently chosen  by  acclamation  a  member  of  the  French 
Academy  of  Sciences;  and  he  received  from  the  Royal 
Society  the  Copley  medal — its  highest  reward.* 


November,  1878. 

At  the  meeting  of  the  British  Association  at  Glasgow  in 
1876 — that  is  to  say,  more  than  fourteen  years  after  its 
delivery  and  publication — the  foregoing  lecture  was  made 
the  cloak  for  an  unseemly  personal  attack  by  Professor 
Tait.  The  anger  which  found  this  uncourteous  vent  dates 
from  1863, f  when  it  fell  to  my  lot  to  maintain,  in  opposi- 
tion to  him  and  a  more  eminent  colleague,  the  position 
whicli  in  1862  I  had  assigned  to  Dr.  Mayer.  In  those  days 
Professor  Tait  denied  to  Mayer  all  originality,  and  he  has 
since,  I  regret  to  say,  never  missed  an  opportunity,  how- 
ever small,  of  carping  at  Maver's  claims.  The  action  of 
the  Academy  of  Sciences  and  of  the  Royal  Society  sum- 
marily disposes  of  this  detraction,  to  which  its  object,  dur- 
ing his  lifetime,  never  vouchsafed  either  remonstrance 
or  reply. 

Some  time  ago  Professor  Tait  published  a  volume  of 
lectures  entitled  "Recent  Advances  in  Physical  Science," 
which  I  have  reason  to  know  has  evoked  an  amount  of  cen- 
sure far  beyond  that  hitherto  publicly  expressed.  Many 

*See  "The  Copley  Medalist  for  1871,"  p.  479. 

f  See  "  Philosophical  Magazine  "  for  this  and  the  succeeding  years. 


ON  FORCE.  293 

of  the  best  heads  on  the  continent  of  Europe  agree  in  their 
rejection  and  condemnation  of  the  historic  portions  of  this 
book.  In  March  last  it  was  subjected  to  a  brief  but  pungent 
critique  by  Du  Bois-Reymond,  the  celebrated  perpetual 
secretary  of  the  Academy  of  Sciences  in  Berlin.  Du  Bois- 
Reymond's  address  was  on  "  National  Feeling,"  and  his 
critique  is  thus  wound  up:  "The  author  of  the  '  Lec- 
tures Ms  not,  perhaps,  sufficiently  well  acquainted  with 
the  history  on  which  he  professes  to  throw  light,  and  on 
the  later  phases  of  which  he  passes  so  unreserved  (s  hrqff) 
a  judgment.  He  thus  exposes  himself  to  the  suspicion — 
which,  unhappily,  is  not  weakened  by  his  other  writings 
— that  the  fiery  Celtic  blood  of  his  country  occasionally 
runs  away  with  him,  converting  him  for  the  time  into  a 
scientific  Chauvin.  Scientific  Chauvinism/'  adds  the 
learned  secretary,  "  from  whicli  German  investigators  have 
hitherto  kept  free,  is  more  reprehensible  (gehdssig)  than 
political  Chauvinism,  inasmuch  as  self-control  (sittHche 
Haltung]  is  more  to  be  expected  from  men  of  science,  than 
from  the  politically  excited  mass."* 

In  the  case  before  this  "expectation"  would,  I  fear,  be 
doomed  to  disappointment.  But  Du  Bois-Reymond  and 
his  countrymen  must  not  accept  the  writings  of  Professor 
Tait  as  representative  of  the  thought  of  England.  Surely 
no  nation  in  the  world  has  more  effectually  shaken  itself 
free  from  scientific  Chauvinism.  Prom  the  day  that  Davy, 
on  presenting  the  Copley  medal  to  Arago,  scornfully 
brushed  aside  that  spurious  patriotism  which  would  run 
national  boundaries  through  the  free  domain  of  science, 
chivalry  toward  foreigners  has  been  a  guidirig  principle  with 
the  Royal  Society 

On  the  more  private  amenities  indulged  in  by  Professor 
Tait,  I  do  not  consider  it  necessary  to  say  a  word. 

*  Festrede,  delivered  before  tbe  Academy  of  Sciences  of  Berlin, 
in  celebration  of  the  birthday  of  the  emperor  and  king,  March  28, 


g94  FRAGMENTS  OF  SCIENCE. 

CHAPTEE  XVII. 

CONTRIBUTIONS  TO  MOLECULAR  PHYSICS.  * 

HAVING  on  previous  occasions  dwelt  upon  the  enormous 
differences  which  exist  among  gaseous  bodies  both  as  regards 
their  power  of  absorbing  and  emitting  radiant  heat,  I  have 
now  to  consider  the  effect  of  a  change  of  aggregation. 
When  a  gas  is  condensed  to  a  liquid,  or  a  liquid  congealed 
to  a  solid,  the  molecules  coalesce,  and  grapple  with  each 
other  by  forces  which  are  insensible  as  lo-ng  as  the  gaseous 
state  is  maintained.  But,  even  in  the  solid  and  liquid  con- 
ditions, the  luminiferous  ether  still  surrounds  the  mole- 
cules: hence,  if  the  acts  of  radiation  and  absorption  depend 
on  them  individually,  regardless  of  their  state  of  aggrega- 
tion, the  change  from  the  gaseous  to  the  liquid  state  ought 
not  materially  to  affect  the  radiant  and  absorbent  power. 
If,  on  the  contrary,  the  mutual  entanglement  of  the  mole- 
cules by  the  force  of  cohesion  be  of  paramount  influence, 
then  we  may  expect  that  liquids  will  exhibit  a  deportment 
toward  radiant  heat  altogether  different  from  that  of  the 
vapors  from  which  they  are  derived. 

The  first  part  of  an  inquiry  conducted  in  1863-64  was 
devoted  to  an  exhaustive  examination  of  this  question. 
Twelve  different  liquids  were  employed,  and  five  different 
layers  of  each,  varying  in  thickness  from  0.02  of  an  inch 
to  0.27  of  an  inch.  The  liquids  were  enclosed,  not  in  glass 
vessels,  which  would  have  materially  modified  the  incident 
heat,  but  between  plates  of  transparent  rock-salt,  which 
only  slightly  affected  the  radiation.  The  source  of  heat 
throughout  these  comparative  experiments  consisted  of  a 
platinum  wire,  raised  to  incandescence  by  an  electric  cur- 
rent of  unvarying  strength.  The  quantities  of  radiant  heat 
absorbed  and  transmitted  by  each  of  the  liquids  at  the 
respective  thicknesses  were  first  determined.  The  vapors 
of  these  liquids  were  subsequently  examined,  the  quantities 
of  vapor  employed  being  rendered  proportional  to  the  quan- 
tities of  liquid  previously  traversed  by  the  radiant  heat. 
The  result  was  that,  for  heat  from  the  same  source,  the 
order  of  absorption  of  liquids  and  of  their  vapors  proved 

*  A  discourse  delivered  at  the  Royal  Institution,  March  18,  1864— 
supplementing,  though  of  prior  date,  the  Rede  Lecture  on  Radiation. 


CONTRIBUTIONS  TO  MOLECULAR  PHYSICS.    295 

absolutely  the  same.  There  is  no  known  exception  to  this 
law;  so  that,  to  determine  the  position  of  a  vapor  as  an 
absorber  or  a  radiator,  it  is  only  necessary  to  determine  the 
position  of  its  liquid. 

This  result  proves  that  the  state  of  aggregation,  as  far 
at  all  events  as  the  liquid  stage  is  concerned,  is  of  altogether 
subordinate  moment — a  conclusion  which  will  probably 
prove  to  be  of  cardinal  importance  in  molecular  physics. 
On  one  important  and  contested  point  it  has  a  special  bear- 
ing. If  the  position  of  a  liquid  as  an  absorber  and  radiator 
determine  that  of  its  vapor,  the  position  of  water  fixes  that 
of  aqueous  vapor.  Water  has  been  compared  with  other 
liquids  in  a  multitude  of  experiments,  and  it  has  been 
found,  both  as  a  radiant  and  as  an  absorbent,  to  transcend 
them  all.  Thus,  for  example,  a  layer  of  bisulphide  of  car- 
bon 0.02  of  an  inch  in  thickness  absorbs  6  per  cent.,  and 
allows  94  per  cent,  of  the  radiation  from  the  red-hot 
platinum  spiral  to  pass  through  it;  benzol  absorbs  43  and 
transmits  57  per  cent,  of  the  same  radiation;  alcohol  absorbs 
67  and  transmits  33  per  cent.,  and  alcohol,  as  an  absorber 
of  radiant  heat,  stands  at  the  head  of  all  liquids  except 
one.  The  exception  is  water.  A  layer  of  this  substance, 
of  the  thickness  above  given,  absorbs  81  per  cent.,  and 
permits  only  19  per  cent,  of  the  radiation  to  pass  through 
it.  Had  no  single  experiment  ever  been  made  upon  the 
vapor  of  water,  its  vigorous  action  upon  radiant  heat 
might  be  inferred  from  the  deportment  of  the  liquid. 

The  relation  of  absorption  and  radiation  to  the  chemical 
constitution  of  the  radiating  and  absorbing  substances  was 
next  briefly  considered.  For  the  six  substances  in  the  list  of 
liquids  examined,  the  radiant  and  absorbent  powers  aug- 
ment as  the  number  of  atoms  in  the  compound  molecule 
augments.  Thus,  bisulphide  of  carbon  has  3  atoms, 
chloroform  5,  iodide  of  ethyl  8,  benzol  12,  and  amylene  15 
atoms  in  their  respective  molecules.  The  order  of  their 
power  as  radiants  and  absorbents  is  that  here  indicated, 
bisulphide  of  carbon  being  the  feeblest  and  amylene  the 
strongest  of  the  six.  Alcohol,  however,  excels  benzol  as 
an  absorber,  though  it  has  but  9  atoms  in  its  molecule; 
but,  on  the  other  ha'nd,  its  molecule  is  rendered  more  com- 
plex by  the  introduction  of  a  new  element.  Benzol  con- 
tains carbon  and  hydrogen,  while  alcohol  contains  carbon, 
hydrogen  and  oxygen.  Thus,  not  only  does  atomic  multi- 


§96  FRAGMENTS  OF  SCIENCE. 

tude  come  into  play  in  absorption  and  radiation — atomic 
complexity  must  also  be  taken  into  account.  1  would 
recommend  to  the  particular  attention  of  chemists  the 
molecule  of  water;  the  deportment  of  this  substance  to- 
ward radiant  heat  being  perfectly  anomalous,  if  the 
chemical  formula  at  present  ascribed  to  it  be  correct. 

Sir  William  Herschel  made  the  important  discovery  that, 
beyond  the  limits  of  the  red  end  of  the  solar  spectrum,  rays  of 
high  heating  power  exist  which  are  incompetent  to  excite 
vision.  The  discovery  is  capable  of  extension.  Dissolving 
iodine  in  the  bisulphide  of  carbon,  a  solution  is  obtained 
which  entirely  intercepts  the  light  of  the  most  brilliant 
flames,  while  to  the  ultra-red  rays  of  such  flames  the  same 
iodine  is  found  to  be  perfectly  diathermic.  The  trans- 
parent bisulphide,  which  is  highly  pervious  to  invisible 
heat,  exercises  on  it  the  same  absorption  as  the  perfectly 
opaque  solution.  A  hollow  prism  filled  with  the  opaque 
liquid  being  placed  in  the  path  of  the  beam  from  an  electric 
lamp,  the  light-spectrum  is  completely  intercepted,  but 
the  heat-spectrurn  may  be  received  upon  a  screen  and  there 
examined.  Falling  upon  a  thermo-electric  pile,  its  in- 
visible presence  is  shown  by  the  prompt  deflection  of  even 
a  coarse  galvanometer. 

What,  then,  is  the  physical  meaning  of  opacity  and 
transparency  as  regards  light  and  radiant  heat?  The 
visible  rays  of  the  spectrum  differ  from  the  invisible  ones 
simply  in  period.  The  sensation  of  light  is  excited  by 
waves  of  ether  shorter  and  more  quickly  recurrent  than  the 
non-visual  waves  which  fall  beyond  the  extreme  red.  But 
why  should  iodine  stop  the  former  and  allow  the  latter  to 
pass?  The  answer  to  this  question  no  doubt  is,  that  the  inter- 
cepted waves  are  those  whose  periods  of  recurrence  coincide 
with  the  periods  of  oscillation  possible  to  the  atoms  of  the 
dissolved  iodine.  The  elastic  forces  which  keep  these 
atoms  apart  compel  them  to  vibrate  in  definite  periods, 
and,  when  these  periods  synchronize  with  those  of  the 
ethereal  waves,  the  latter  are  absorbed.  Briefly  defined, 
then,  transparency  in  liquids,  as  well  as  in"  gases,  is 
synonymous  with  discord,  while  opacity  is  synonymous 
with  accord,  between  the  periods  of  tire  waves  of  ether  and 
those  of  the  molecules  on  which  they  impinge. 

According  to  this  view  transparent  and  colorless  sub- 
stances owe  their  transparency  to  the  dissonance  existing 


CONTRIBUTIONS  TO  MOLECULAR  PHYSICS.      297 

between  the  oscillating  periods  of  their  atoms  and  those  of 
the  waves  of  the  whole  visible  spectrum.  From  the  prev- 
alence of  transparency  in  compound  bodies,  the  general 
discord  of  the  vibrating  periods  of  their  atoms  with  the 
light-giving  waves  of  the  spectrum  may  be  inferred;  while 
their  synchronism  with  the  ultra-red  periods  is  to  be  infer- 
red from  their  opacity  to  the  ultra-red  rays.  Water 
illustrates  this  in  a  most  striking  manner.  It  is  highly 
transparent  to  the  luminous  rays,  which  proves  that  its 
atoms  do  not  readily  oscillate  in  the  periods  which  excite 
vision.  It  is  highly  opaque  to  the  ultra-red  undulations, 
which  proves  the  synchronism  of  its  vibrating  periods  with 
those  of  the  longer  waves. 

If,  then,  to  the  radiation  from  any  source  water  shows 
itself  eminently  or  perfectly  opaque,  we  may  infer  that 
the  atoms  whence  the  radiation  emanates  oscillate  in  ultra- 
red  periods:  Let  us  apply  this  test  to  the  radiation  from  a 
flame  of  hydrogen.  This  flame  consists  mainly  of  incan- 
descent aqueous  vapor,  the  temperature  of  "which,  as 
calculated  by  Bunsen,  is  3,259  degrees  C.,  so  that,  if  the 
penetrative  power  of  radiant  heat,  as  generally  supposed, 
augment  with  the  temperature  of  its  source,  we  may  expect 
the  radiation  from  this  flame  to  be  copiously  transmitted 
by  water.  While,  however,  a  layer  of  the  bisulphide  of 
carbon  0.07  of  an  inch  in  thickness  transmits  72  per  cent, 
of  the  incident  radiation,  and  while  every  other  liquid  ex- 
amined transmits  more  or  less  of  the  heat,  a  layer  of  water 
of  the  above  thickness  is  entirely  opaque  to  the  radiation 
from  the  hydrogen  flame.  Thus  we  establish  accord  be- 
tween the  periods  of  the  atoms  of  cold  water  and  those  of 
aqueous  vapor  at  a  temperature  of  3,259  degrees  C.  But 
the  periods  of  water  have  already  been  proved  to  be  ultra-red 
— hence  those  of  the  hydrogen  flame  must  be  sensibly 
ultra-red  also.  Tiie  absorption  by  dry  air  of  the  heat 
emitted  by  a  platinum  spiral  raised  to  incandescence  by 
electricity  is  insensible,  while  that  by  the  ordinary  undried 
air  is  6  per  cent.  Substituting  for  the  platinum  spiral  a 
hydrogen  flame,  the  absorption  by  dry  air  still  remains 
insensible,  while  that  of  the  undried  air  rises  to  20  per 
cent,  of  the  entire  radiation.  The  temperature  of  the 
hydrogen  flame  is,  as  stated,  3,259  degrees  C.;  that  of  the 
aqueous  vapor  of  the  air  20  degrees  C.  Suppose,  then, 
the  temperature  of  aqueous  vapor  to  rise  from  20  degrees 


298  FRAGMENTS  OF  SCIENCE. 

C.  to  3,259  degrees  C.,  we  must  conclude  that  the  aug- 
mentation of  temperature  is  applied  to  an  increase  of 
amplitude  or  width  of  swing,  and  not  to  the  introduc- 
tion of  quicker  periods  into  the  radiation. 

The  part  played  by  aqueous  vapor  in  the  economy  of 
nature  is  far  more  wonderful  than  has  been  hitherto  sup- 
posed. To  nourish  the  vegetation  of  the  earth  the  actinic 
and  luminous  rays  of  the  sun  must  penetrate  our  atmos- 
phere; and  to  such  rays  aqueous  vapor  is  eminently  trans- 
parent. The  violet  and  the  ultra-violet  rays  pass  through 
it  with  freedom.  To  protect  vegetation  from  destructive 
chills  the  terrestrial  rays  must  be  checked  in  their  transit 
toward  stellar  space;  and  this  is  accomplished  by  the 
aqueous  vapor  diffused  through  the  air.  This  substance  is 
the  great  moderator  of  the  earth's  temperature,  bringing 
its  extremes  into  proximity,  and  obviating  contrasts  between 
day  and  night  which  would  render  life  insupportable.  But 
we  can  advance  beyond  this  general  statement,  now  that 
we  know  the  radiation  from  aqueous  vapor  is  intercepted, 
in  a  special  degree,  by  water,  and,  reciprocally,  the  radi- 
ation from  water  by  aqueous  vapor;  for  it  follows  from  this 
that  the  very  act  of  nocturnal  refrigeration  which  produces 
the  condensation  of  aqueous  vapor  at  the  surface  of  the 
earth — giving,  as  it  were,  a  varnish  of  water  to  that  surface 
— imparts  to  terrestrial  radiation  that  particular  character 
which  disqualifies  it  from  passing  through  the  earth's 
atmosphere  and  losing  itself  in  space. 

And  here  we  come  to  a  question  in  molecular  physics 
which  at  the  present  moment  occupies  attention.  By 
allowing  the  violet  and  ultra-violet  rays  of  the  spectrum  to 
fall  upon  sulphate  of  quinine  and  other  substances,  Pro- 
fessor Stokes  has  changed  the  periods  of  those  rays. 
Attempts  have  been  made  to  produce  a  similar  result  at  the 
other  end  of  the  spectrum — to  convert  the  ultra-red  periods 
into  periods  competent  to  excite  vision — but  hitherto  with- 
out success.  Such  a  change  of  period,  I  agree  with  Dr. 
Miller  in  believing,  occurs  when  the  limelight  is  produced 
by  an  oxyhydrogen  flame.  In  this  common  experiment 
there  is  an  actual  breaking  up  of  long  periods  into  short 
ones — a  true  rendering  of  unvisual  periods  visual.  The 
change  of  refrangi'bility  here  effected  differs  from  that  of 
Professor  Stokes;  firstly,  by  its  being  in  the  opposite  direc- 
tion—that is,  from  a  lower  refrangibility  to  a  higher;  and, 


CONTRIBUTIONS  TO  MOLECULAR  PHYSICS.      299 

secondly,  in  the  circumstance  that  the  lime  is  heated  by 
the  collision  of  the  molecules  of  aqueous  vapor,  before 
their  heat  has  assumed  the  radiant  form.  But  it  cannot 
be  doubted  that  the  same  effect  would  be  produced  by 
radiant  heat  of  the  same  periods,  provided  the  motion  of 
the  ether  could  be  rendered  sufficiently  intense.*  The 
effect  in  principle  is  the  same,  whether  we  consider  the 
lime  to  be  struck  by  a  particle  of  aqueous  vapor  oscillating 
at  a  certain  rate,  or  by  a  particle  of  ether  oscillating  at  the 
same  rate. 

By  plunging  a  platinum  wire  into  a  hydrogen  flame  we 
cause  it  to  glow,  and  thus  introduce  shorter  periods  into 
the  radiation.  These,  as  already  stated,  are  in  discord 
with  the  atomic  vibrations  of  water:  hence  we  may  infer 
that  the  transmission  through  water  will  be  rendered  more 
copious  by  the  introduction  of  the  wire  into  the  flame. 
Experiment  proves  this  conclusion  to  be  true.  Water, 
from  being  opaque,  opens  a  passage  to  6  per  cent,  of  the 
radiation  from  the  spiral.  A  thin  plate  of  colorless  glass, 
moreover,  transmits  58  per  cent,  of  the  radiation  from  the 
hydrogen  flame;  but  when  the  flame  and  spiral  are 
employed,  78  per  cent,  of  the  heat  is  transmitted. 

For  an  alcohol  flame  Knoblauch  and  Melloni  found  glass 
to  be  less  transparent  than  for  the  same  flame  with  a  plati- 
num spiral  immersed  in  it;  but  Melloni  afterward  showed 
that  the  result  was  not  general — that  black  glass  and  black 
mica  were  decidedly  more  diathermic  to  the  radiation  from 
the  pure  alcohol  flrime.  Melloni  did  not  explain  this,  but 
the  reason  is  now  obvious.  The  mica  and  glass  owe  their 
blackness  to  the  carbon  diffused  through  them.  This  car- 
bon, as  first  proved  by  Melloni,  is  in  some  measure  trans- 
parent to  the  ultra-red  rays,  and  I  have  myself  succeeded 
in  transmitting  between  40  and  50  per  cent,  of  the  radia- 
tion from  a  hydrogen  flame  through  a  layer  of  carbon  whioh 
intercepted  the  light  of  an  intensely  brilliant  flame.  The 
products  of  combustion  of  alcohol  are  carbonic  acid  and 
aqueous  vapor,  the  heat  of  which  is  almost  wholly  ultra-red. 
For  this  radiation,  then,  the  carbon  is  in  a  considerable 
degree  transparent,  while  for  the  radiation  from  the  plati- 
num spiral,  it  is  in  a  great  measure  opaque.  The  platinum 
wire,  therefore,  which  augmented  the  radiation  through 
the  pure  glass,  augmented  the  absorption  of  the  black  glass 
and  mica. 

*  This  was  soon  afterward  accomplished.     See  pp.  35,  36. 


300  FRAGMENTS 

No  more  striking  or  instructive  illustration  of  the 
influence  of  coincidence  could  be  adduced  than  that  fur- 
nished by  the  radiation  from  a  carbonic  oxide  flarne.  Here 
the  product  of  combustion  is  carbonic  acid;  and  on  the 
radiation  from  this  flame  even  the  ordinary  carbonic  acid 
of  the  atmosphere  exerts  a  powerful  effect.  A  quantity  of 
the  gas,  only  one-thirtieth  of  an  atmosphere  in  density, 
contained  in  a  polished  brass  tube  four  feet  long,  intercepts 
50  per  cent,  of  the  radiation  from  the  carbonic  oxide  flame. 
For  the  heat  emitted  by  lampblack,  defiant  gas  is  a  far 
more  powerful  absorber  than  carbonic  acid;  in  fact,  for 
such  heat,  with  one  exception,  carbonic  acid  is  the  most 
feeble  absorber  to  be  found  among  the  compound  gases. 
Moreover,  for  the  radiation  from  a  hydrogen  flame  olefiant 
gas  possesses  twice  the  absorbent  power  of  carbonic  acid, 
while  for  the  radiation  from  the  carbonic  oxide  flame,  at  a 
common  pressure  of  one  inch  of  mercury,  the  absorption 
by  carbonic  acid  is  more  than  twice  that  of  olefiant  gas. 
Thus  we  establish  the  coincidence  of  period  between  car- 
bonic acid  at  a  temperature  of  20  degrees  C.  and  carbonic 
acid  at  a  temperature  of  over  3,000  degrees  C.,  the  periods 
of  oscillation  of  both  the  incandescent  and  the  cold  gas 
belonging  to  the  ultra-red  portion  of  the  spectrum. 

It  will  be  seen  from  the  foregoing  remarks  and  experi- 
ments how  impossible  it  is  to  determine  the  effect  of  tem- 
perature pure  and  simple  on  the  transmission  of  radiant 
heat  if  different  sources  of  heat  be  employed.  Throughout 
such  an  examination  the  same  oscillating  atoms  ought  to 
be  retained.  This  is  done  by  heating  a  platinum  spiral  by 
an  electric  current,  the  temperature  meanwhile  varying 
between  the  widest  possible  limits.  Their  comparative 
opacity  to  the  ultra-red  rays  shows  the  general  accord  of 
the  oscillating  periods  of  the  vapors  referred  to  at  the  com- 
mencement of  this  lecture  with  those  of  the  ultra-red  un- 
dulations. Hence,  by  gradually  heating  a  platinum  wire 
from  darkness  up  to  whiteness,  we  ought  gradually  to 
augment  the  discord  between  it  and  these  vapors,  and  thus 
augment  the  transmission.  Experiment  entirely  confirms 
this  conclusion.  Formic  ether,  for  example,  absorbs  45 
per  cent,  of  the  radiation  from  a  platinum  spiral  heated  to 
barely  visible  redness;  32  per  cent,  of  the  radiation  from 
the  same  spiral  at  a  red  heat;  26  per  cent,  of  the  radiation 
from  a  white-hot  spiral,  and  only  21  per  cent,  when  the 


CONTRIBUTIONS  TO  MOLECULAR  PHYSICS.        301 

spiral  is  brought  near  its  point  of  fusion.  Kemarkable 
cases  of  inversion  as  to  transparency  also  occur.  For  barely 
visible  redness  formic  ether  is  more  opaque  than  sulphuric; 
for  a  bright  red  heat  both  are  equally  transparent;  while, 
for  a  white  heat,  and  still  more  for  a  higher  temperature, 
sulphuric  ether  is  more  opaque  than  formic.  This 
result  gives  us  a  clear  view  of  the  relationship  of  the 
two  substances  to  the  luminiferous  ether.  As  we  intro- 
duce waves  of  shorter  period  the  sulphuric  ether  aug- 
ments most  rapidly  in  opacity;  that  is  to  say,  its  accord 
with  the  shorter  waves  is  greater  than  that  of  the  formic. 
Hence  we  may  infer  that  the  atoms  of  formic  ether 
oscillate,  on  the  whole,  more  slowly  than  those  of  sulphuric 
ether. 

When  the  source  of  heat  is  a  Leslie's  cube  coated  with 
lampblack  and  filled  with  boiling  water,  the  opacity  of 
formic  ether  in  comparison  with  sulphuric  is  very  decided. 
'With  this  source  also  the  positions  of  chloroform  and  iodide 
of  methyl  are  inverted.  For  a  white-hot  spiral,  the  absorp- 
tion of  chloroform  vapor  being  10  per  cent.,  that  of  iodide 
of  methyl  is  16;  with  the  blackened  cube  as  source,  the 
absorption  by  chloroform  is  22  per  cent.,  while  that  by  the 
iodide  of  methyl  is  only  19.  This  inversion  is  not  the 
result  of  temperature  merely;  for  when  a  platinum  wire, 
heated  to  the  temperature  of  boiling  water,  is  employed  as 
a  source,  the  iodide  continues  to  be  the  most  powerful 
absorber.  All  the  experiments  hitherto  made  go  to  prove 
that  from  heated  lampblack  an  emission  takes  place  which 
synchronizes  in  an  especial  manner  wrth  chloroform.  For 
the  cube  at  100  degrees  C.,  coated  with  kimpblack,  the 
absorption  by  chloroform  is  more  than  three  times  that  by 
bisulphide  of  carbon;  for  the  radiation  from  the  most 
luminous  portion  of  a  gas-flame  the  absorption  by  chloro- 
form is  also  considerably  in  excess  of  that  by  bisulphide 
of  carbon;  while,  for  the  flame  of  a  Bunsen's  burner,  from 
which  the  incandescent  carbon  particles  are  removed  by 
the  free  admixture  of  air,  the  absorption  by  bisulphide  of 
carbon  is  nearly  twice  that  by  chloroform.  The  removal 
of  the  carbon  particles  more  than  doubles  the  relative  trans- 
parency of  the  chloroform.  Testing,  moreover,  the  radi- 
ation from  various  parts  of  the  same  flame,  it  was  found 
that  for  the  blue  base  of  the  flame  the  bisulphide  of  carbon 
was  most  opaque,  while  for  all  other  parts  of  the  flaine  the. 


302  FRAGMENTS  OF  SCIENCE. 

chloroform  was  most  opaque.  For  the  radiation  from  a 
very  small  gas-flame,  consisting  of  a  blue  base  and  a  small 
white  tip,  the  bisulphide  was  also  most  opaque,  and  its 
opacity  very  decidedly  exceeded  that  of  the  chloroform 
when  the  source  of  heat  was  the  flame  of  bisulphide  of 
carbon.  Comparing  the  radiation  from  a  Leslie's  cube 
coated  with  isinglass  with  that  from  a  similar  cube  coated 
with  lampblack,  at  the  common  temperature  of  100  de- 
grees C.,  it  was  found  that,  out  of  eleven  vapors,  all  but  one 
absorbed  the  radiation  from  the  isinglass  most  powerfully; 
the  single  exception  was  chloroform. 

It  is  worthy  of  remark  that  whenever,  through  a  change 
of  source,  the  position  of  a  vapor  as  an  absorber  of  radiant 
heat  was  altered,  the  position  of  the  liquid  from  which  the 
vapor  was  derived  underwent  a  similar  change. 

It  is  still  a  point  of  difference  between  eminent  investi- 
gators whether  radiant  heat,  up  to  a  temperature  of  100  de- 
grees C.,  is  monochromatic  or  not.  Some  affirm  this;  some 
deny  it.  A  long  series  of  experiments  enables  me  to  state 
that  probably  no  two  substances  at  a  temperature  of  100  de- 
grees C.  emit  heat  of  the  same  quality.  The  heat  emitted  by 
isinglass,  for  example,  is  different  from  that  emitted  by 
lampblack,  and  the  heat  emitted  by  cloth,  or  paper,  differs 
from  both.  It  also  a  subject  of  discussion  whether  rock-salt 
is  equally  diathermic  to  all  kinds  of  calorific  rays;  the  differ- 
ences affirmed  to  exist  by  some  investigators  being  ascribed 
by  others  to  differences  of  incidence  from  the  various 
sources  employed.  MM.  de  la  Provostaye  and  Desains 
maintain  the  former  view,  Melloni  and  M.  Knoblauch 
maintain  the  fetter.  I  tested  this  point  without  changing 
anything  but  the  temperature  of  the  source;  its  size,  dis- 
tance, and  surroundings  remaining  the  same.  The  experi- 
ments proved  rock-salt  to  be  colored  thermally.  It  is 
more  opaque,  for  example,  to  the  radiation  from  a  barely 
visible  spiral  than  to  that  from  a  white-hot  one. 

In  regard  to  the  relation  of  radiation  to  conduction,  if 
we  define  radiation,  internal  as  well  as  external,  as  the 
communication  of  motion  from  the  vibrating  atoms  to  the 
ether,  we  may,  I  think,  by  fair  theoretic  reasoning,  reach 
the  conclusion  that  the  best  radiators  ought  to  prove  the 
worst  conductors.  A  broad  consideration  of.  the  subject 
shows  at  once  the  general  harmony  of  this  conclusion  with 
observed  facts.  Organic  substances  are  all  excellent  radi- 


LIFE  AND  LETTERS  OF  FAR  AD  AT.  303 

ators;  they  are  also  extremely  bad  conductors.  The 
moment  we  pass  from  the  metals  to  their  compounds  we 
pass  from  good  conductors  to  bad  ones,  and  from  bad 
radiators  to  good  ones.  Water,  among  liquids,  is  probably 
the  worst  conductor;  it  is  the  best  radiator.  Silver,  among 
solids,  is  the  best  conductor;  it  is  the  worst  radiator.  The 
excellent  researches  of  MM.  de  la  Provostaye  and  Desains 
furnish  a  striking  illustration  of  what  I  am  inclined  to 
regard  as  a  natural  law — that  those  atoms  which  transfer 
the  greatest  amount  of  motion  to  the  ether,  or,  in  other 
words,  radiate  most  powerfully,  are  the  least  competent  to 
communicate  motion  to  each  other,  or,  in  other  words,  to 
propagate  by  conduction  readily. 


CHAPTER  XVIII. 

LIFE   AND   LETTERS   OF   FARADAY. 

1870. 

UNDERTAKEN  and  executed  in  a  reverent  and  loving 
spirit,  the  work  of  Dr.  Bence  Jones  makes  Faraday  the 
virtual  writer  of  his  own  life.  Everybody  now  knows  the 
story  of  the  philosopher's  birth;  that  his  father  was  a 
smith;  that  he  was  born  at  Newingtou  Butts  in  1791;  that 
he  ran  along  the  London  pavements,  a  bright-eyed  errand 
boy,  with  a  load  of  brown  curls  upon  his  head  and  a 
packet  of  newspapers  under  his  arm;  that  the  lad's  master 
was  a  bookseller  and  bookbinder — a  kindly  man,  who 
became  attached  to  the  little  fellow,  and  in  due  time  made 
him  his  apprentice  without  fee;  that  during  his  apprentice- 
ship he  found  his  appetite  for  knowledge  provoked  and 
strengthened  by  the  books  he  stitched  and  covered.  Thus 
he  grew  in  wisdom  and  stature  to  his  year  of  legal  manhood, 
when  he  appears  in  the  volumes  before  us  as  a  writer  of 
letters,  which  reveal  his  occupation,  acquirements,  and 
tone  of  mind.  His  correspondent  was  Mr.  Abbott,  a  mem- 
ber of  the  Society  of  Friends,  who,  with  a  forecast  of  his 
correspondent's  greatness,  preserved  his  letters  and  pro- 
duced them  at  the  proper  time. 

In  later  years  Faraday  always  carried  in  his  pocket  a 
blank  card,  on  which  he  jotted  down  in  pencil  his  thoughts 
and  memoranda.  He  made  his  notes  in  the  laboratory,  in 
the  theater,  and  in  the  streets.  This  distrust  of  his  mem- 


304  FRAGMENTS  OF  SCIENCE. 

ory  reveals  itself  in  his  first  letter  to  Abbot.  To  a  proposi- 
tion that  no  new  inquiry  should  be  started  between  them 
before  the  old  one  had  been  exhaustively  discussed,  Faraday 
objects.  "Your  notion, "  he  says,  "I  can  hardly  allow,  for 
the  following  reason:  ideas  and  thoughts  spring  up  in  my 
mind  which  are  irrevocably  lost  for  want  of  noting  at  the 
time."  Gentle  as  he  seemed,  he  wished  to  have  his  own 
way,  and  he  had  it  throughout  his  life.  Differences  of 
opinion  sometimes  arose  between  the  two  friends,  and  then 
they  resolutely  faced  each  other.  "  I  accept  your  offer  to 
fight  it  out  with  joy,  and  shall  in  the  battle  of  experience 
cause  not  pain,  but,  I  hope,  pleasure."  Faraday  notes  his 
own  impetuosity,  and  incessantly  checks  it.  There  is  at 
times  something  almost  mechanical  in  his  self-restraint. 
In  another  nature  it  would  have  hardened  into  mere 
"correctness"  of  conduct;  but  his  overflowing  affections 
prevented  this  in  his  case.  The  habit  of  self-control 
became  a  second  nature  to  him  at  last,  and  lent  serenity  to 
his  later  years. 

In  October,  1812,  he  was  engaged  by  a  Mr.  De  la  Roche 
as  a  journeyman  bookbinder;  but  the  situation  did  not  suit 
him.  His  master  appears  to  have  been  an  austere  and 
passionate  man,  arid  Faraday  was  to  the  last  degree  sensi- 
tive. All  his  life  he  continued  so.  He  suffered  at  times 
from  dejection;  and  a  certain  grimness,  too,  pervaded  his 
moods.  "  At  present,"  he  writes  to  Abbott,  "  I  am  as  seri- 
ous as  you  can  be,  and  would  not  scruple  to  speak  a  truth 
to  any  human  being,  whatever  repugnance  it  might  give 
rise  to.  Being  in  this  state  of  mind,  I  should  have  re- 
frained from  writing  to  you,  did  I  not  conceive  from  the 
general  tenor  of  your  letters  that  your  mind  is,  at  proper 
times,  occupied  upon  serious  subjects  to  the  exclusion  of 
those  that  are  frivolous."  Plainly  he  had  fallen  into  that 
stern  Puritan  mood,  which  not  only  crucifies  the  affections 
and  lusts  of  him.  who  harbors  it,  but  is  often  a  cause  of 
disturbed  digestion  to  his  friends. 

About  three  months  after  his  engagement  with  De  la 
Roche,  Faraday  quitted  him  and  bookbinding  together. 
He  had  heard  Davy,  copied  his  lectures,  and  written  to 
him,  entreating  to  be  released  from  Trade,  which  he  hated, 
and  enabled  to  pursue  Science.  Davy  recognized  the 
merit  of  his  correspondent,  kept  his  eye  upon  him,  and, 
when  occasion  offered,  drove  to  his  door  and  sent  in  u  letter, 


LIFE  AND  LETTERS  OF  FARADAY.  305 

offering  him  the  post  of  assistant  in  the  laboratory  of  the 
Royal  Institution.  He  was  engaged  March  1,  1813,  and 
on  the  8th  we  find  him  extracting  the  sugar  from  beet- 
root. He  joined  the  City  Philosophical  Society  which 
had  been  founded  by  Mr.  Tatum  in  1808.  "  The  disci- 
pline was  very  sturdy,  the  remarks  very  plain,  and  the 
results  most  valuable."  Faraday  derived  great  profit 
from  this  little  association.  In  the  laboratory  he  had  a 
discipline  sturdier  still.  Both  Davy  and  himself  were  at 
this  time  frequently  cut  and  bruised  by  explosions  of 
chloride  of  nitrogen.  One  explosion  was  so  rapid  "  as  to 
blow  my  hand  open,  tear  away  a  part  of  one  nail,  and  make 
my  fingers  so  sore  that  I  cannot  use  them  easily."  In 
another  experiment  "  the  tube  and  receiver  were  blown  to 
pieces,  I  got  a  cut  on  the  head,  and  Sir  Humphry  a  bruise 
on  his  hand."  And  again  speaking  of  the  same  substance, 
he  says,  "  when  put  in  the  pump  and  exhausted,  it  stood 
for  a  moment,  and  then  exploded  with  a  fearful  noise. 
Both  Sir  H.  and  I  had  masks  on,  but  I  escaped  this  time 
the  best.  Sir  H.  had  his  face  cut  in  two  places  about  the 
chin,  and  a  violent  blow  on  the  forehead  struck  through 
a  considerable  thickness  of  silk  and  leather."  It  was  this 
same  substance  that  blew  out  the  eye  of  Dulong. 

Over  and  over  again,  even  at  this  early  date,  we  can  dis- 
cern the  quality  which,  compounded  with  his  rare  intel- 
lectual power,  made  Faraday  a  great  experimental  phi- 
losopher. This  was  his  desire  to  see  facts,  and  not  to  rest 
contented  with  the  descriptions  of  them.  He  frequently 
pits  the  eye  against  the  ear,  and  affirms  the  enormous 
superiority  of  the  organ  of  vision.  Late  in  life  I  have 
heard  him  say  that  he  could  never  fully  understand  an  ex- 
periment until  he  had  seen  it.  But  he  did  not  confine 
himself  to  experiment.  He  aspired  to  be  a  teacher,  and 
reflected  and  wrote  upon  the  method  of  scientific  exposi- 
tion. "A  lecturer,"  he  observes,  "  should  appear  easy  and 
collected,  undaunted  and  unconcerned:"  still  "  his  whole 
behavior  should  evince  respect  for  his  audience."  These 
recommendations  were  afterward  in  great  part  embodied 
by  himself.  I  doubt  his  "  unconcern,"  but  his  fearless- 
ness was  often  manifested.  It  used  to  rise  within  him  as 
a  wave,  which  carried  both  him  and  his  audience  along 
with  it.  On  rare  occasions  also,  when  he  felt  himself  and 
his  subject  hopelessly  unintelligible,  he  suddenly  evoked  a 


306  FRAGMENTS  OF  SCIENCE. 

certain  recklessness  of  thought,  and,  without  halting  to 
extricate  his  bewildered  followers,  he  would  dash  alone 
through  the  jungle  into  which  he  had  unwittingly  led 
them;  thus  saving  them  from  ennui  by  the  exhibition  of 
a  vigor  which,  for  the  time  being,  they  could  neither  share 
nor  comprehend. 

In  October,  1813,  he  quitted  England  with  Sir  Humphry 
and  Lady  Davy.  During  his  absence  he  kept  a  journal, 
from  which  copious  and  interesting  extracts  have  been 
made  by  Dr.  Bence  Jones.  Davy  was  considerate,  prefer- 
ring at  times  to  be  his  own  servant  rather  than  impose  on 
Faraday  duties  which  he  disliked.  But  Lady  Davy  was  the 
reverse.  She  treated  him  as  an  underling;  he  chafed 
under  the  treatment,  and  was  often  on  the  point  of  return- 
ing home.  They  halted  at  Geneva.  De  la  Rive,  the 
elder,  had  known  Davy  in  1799,  and,  by  his  writings  in  the 
"  Bibliotheque  Britannique,"  had  been  the  first  to  make 
the  English  chemist's  labors  known  abroad.  He  welcomed 
Davy  to  his  country  residence  in  1814.  Both  were  sports- 
men, and  they  often  went  out  shooting  together.  On  these 
occasions  Faraday  charged  Davy's  gun  while  De  la  Rive 
charged  his  own.  Once  the  Genevese  philosopher  found 
himself  by  the  side  of  Faraday,  and  in  his  frank  and  genial 
way  entered  into  conversation  with  the  young  man.  It 
was  evident  that  a  person  possessing  such  a  charm  of 
manner  and  such  high  intelligence  could  be  no  mere 
servant.  On  inquiry  De  la  Rive  was  somewhat  shocked  to 
find  that  the  soidisant  domestique\v&s  re&\\y  preparateur  in 
the  laboratory  of  the  Royal  Institution;  and  he  immediately 
proposed  that  Faraday  thenceforth  should  join  the  masters 
instead  of  the  servants  at  their  meals.  To  this  Davy,  probably 
out  of  weak  deference  to  his  wife,  objected;  but  an  ar- 
rangement was  come  to  that  Faradav  thenceforward  should 
have  his  food  in  his  own  room.  Rumor  states  that  a  dinner 
in  honor  of  Faraday  was  given  by  De  la  Rive.  This  is  a 
delusion;  there  was  no  such  banquet;  but  Faraday  never 
forgot  the  kindness  of  the  friend  who  saw  his  merit  when 
he  was  a  mere  gar p on  de  laboratoire.* 

*  While  confined  last  autumn  at  Geneva  by  the  effects  of  a  fall  in 
the  Alps,  my  friends,  with  a  kindness  I  can  never  forget,  did  all 
that  friendship  could  suggest  to  render  my  captivity  pleasant  to 
me.  M.  De  la  Rive  then  wrote  out  for  me  the  full  account,  of 
which  the  foregoing  is  a  condensed  abstract.  It  was  at  the  desire  of 


LIFE  AND  LETTERS  OF  FARAD  A  T.  307 

He  returned  in  1815  to  the  Royal  Institution.  Here  he 
helped  Davy  for  years;  he  worked  also  for  himself,  and 
lectured  frequently  at  the  City  Philosophical  Society.  He 
took  lessons  in  elocution,  happily  without  damage  to  his 
natural  force,  earnestness,  and  grace  of  delivery.  He  was 
never  pledged  to  theory,  and  he  changed  in  opinion  as 
knowledge  advanced.  With  him  life  was  growth.  In 
those  early  lectures  we  hear  him  say,  "  In  knowledge,  that 
man  only  is  to  be  contemned  and  despised  who  is  not  in  a 
state  of  transition/'  And  again:  "Nothing  is  more  dif- 
ficult and  requires  more  caution  than  philosophical  deduc- 
tion, nor  is  there  anything  more  ad  verse  to  its  accuracy  than 
fixity  of  opinion."  Not  that  he  was  wafted  about  by  every 
wind  of  doctrine;  but  that  he  united  flexibility  with  his 
strength.  In  striking  contrast  with  this  intellectual  ex- 
pansiveness  was  his  fixity  in  religion,  but  this  is  a  subject 
which  cannot  be  discussed  here. 

Of  all  the  letters  published  in  these  volumes  none  possess 
a  greater  charm  than  those  of  Faraday  to  his  wife.  Here, 
as  Dr.  Bence  Jones  truly  remarks,  "  he  laid  open  all  his 
mind  and  the  whole  of  his  character,  and  what  can  be 
made  known  can  scarcely  fail  to  charm  every  one  by  its 
loveliness,  its  truthfulness,  and  its  earnestness."  Abbott 
and  he  'sometimes  swerved  into  word-play  about  love; 
but  up  to  1820,  or  thereabouts,  the  passion  was  potential 
merely.  Faraday's  journal  indeed  contains  entries  which 
show  that  he  took  pleasure  in  the  assertion  of  his  contempt 
for  love;  but  these  very  entries  became  links  in  his  destiny. 
It  was  through  them  that  he  became  acquainted  with  one 
who  inspired  him  with  a  feeling  which  only  ended  with  his 
life.  His  biographer  has  given  us  the  means  of  tracing 
the  varying  moods  which  preceded  his  acceptance.  They 
reveal  more  than  the  common  alternations  of  light  and 
gloom;  at  one  moment  he  wishes  that  his  flesh  might  melt 
and  that  he  might  become  nothing;  at  another  he  is 
intoxicated  with  hope.  The  impetuosity  of  his  character 
was  then  unchastened  by  the  discipline  to  which  it  was 
subjected  in  after  years.  The  very  strength  of  his  passion 
proved  for  a  time  a  bar  to  its  advance,  suggesting,  as  it 
did,  to  the  conscientious  mind  of  Miss  Barnard,  doubts  of 

Dr.  Bence  Jones  that  I  asked  him  to  do  so.  The  rumor  of  a  banquet 
at  Geneva  illustrates  the  tendency  to  substitute  for  the  youth  of  1814 
the  Faraday  of  later  years. 


308  FRAGMENTS  OF  SCIENCE. 

her  capability  to  return  it  with  adequate  force.  But  they 
met  again  and  again,  and  at  each  successive  meeting  he 
found  his  heaven  clearer,  until  at  length  he  was  able  to  say, 
"  Not  a  moment's  alloy  of  this  evening's  happiness  occurred. 
Everything  was  delightful  to  the  last  moment  of  my  stay 
with  my  companion,  because  she  was  so."  The  turbulence 
of  doubt  subsided,  and  a  calm  and  elevating  confidence  took 
its  place.  "What  can  I  call  myself,"  he  writes  to  her  in 
a  subsequent  letter,  "  to  convey  most  perfectly  my  affection 
and  love  for  you  ?  Can  I  or  can  truth  say  more  than  that  for 
this  world  I  am  yours?  "  Assuredly  he  made  his  profession 
good,  and  no  fairer  light  falls  upon  his  character  than  that 
which  reveals  his  relations  to  his  wife.  Never,  I  believe, 
existed  a  manlier,  purer,  steadier  love.  Like  a  burning 
diamond,  it  continued  to  shed,  for  six- and -forty  years,  its 
white  and  smokeless  glow. 

Faraday  was  married  on  June  12,  1821;  and  up  to  this 
date  Davy  appears  throughout  as  his  friend.  Soon  after- 
ward, however,  disunion  occurred  between  them,  which, 
while  it  lasted,  must  have  given  Faraday  intense  pain.  It 
is  impossible  to  doubt  the  honesty  of  conviction  with  which 
this  subject  has  been  treated  by  Dr.  Bence  Jones,  and  there 
may  be  facts  known  to  him,  but  not  appearing  in  these 
volumes,  which  justify  his  opinion  that  Davy  in  those  days 
had  become  jealous  of  Faraday.  This,  which  is  the  prev- 
alent belief,  is  also  reproduced  in  an  excellent  article  in 
the  March  number  of  "  Eraser's  Magazine."  But  the  best 
analysis  I  can  make  of  the  data  fails  to  present  Davy  in 
this  light  to  me.  The  facts,  as  I  regard  them,  are  briefly 
these. 

In  1820,  Oersted  of  Copenhagen  made  the  celebrated 
discovery  which  connects  electricity  with  magnetism,  and 
immediately  afterward  the  acute  mind  of  Wollaston  per- 
ceived that  a  wire  carrying  a  current  ought  to  rotate  round 
its  own  axis  under  the  influence  of  a  magnetic  pole.  In 
1821  he  tried,  but  failed,  to  realize  this  result  in  the  lab- 
oratory of  the  Eoyal  Institution.  Faraday  was  not  present 
at  the  moment,  but  he  came  in  immediately  afterward  and 
heard  the  conversation  of  Wollaston  and  Davy  about  the 
experiment.  He  had  also  heard  a  rumor  of  a  wager  that 
Dr.  Wollaston  would  eventually  succeed. 

This  was  in  April.  In  the  autumn  of  the  same  year 
Faraday  wrote  a  history  of  electro-magnetism,  and  repeated 


LIFE  AND  LETTERS  OF  FARADA  T.  309 

for  himself  the  experiments  which  he  described.  It  was 
while  thus  instructing  himself  that  he  succeeded  in  caus- 
ing a  wire,  carrying  an  electric  current,  to  rotate  round  a 
magnetic  pole.  This  was  not  the  result  sought  by  Wollas- 
ton,  but  it  was  closely  related  to  that  result. 

The  strong  tendency  of  Faraday's  mind  to  look  upon 
the  reciprocal  actions  of  natural  forces  gave  birth  to  his 
greatest  discoveries;  and  we,  who  know  this,  should  be 
justified  in  concluding  that,  even  had  Wollaston  not  pre- 
ceded him,  the  result  would  have  been  the  same.  But  in 
judging  Davy  we  ought  to  transport  ourselves  to  his  time, 
and  carefully  exclude  from  our  thoughts  and  feelings  that 
noble  subsequent  life,  which  would  render  simply  impos- 
sible the  ascription  to  Faraday  of  anything  unfair.  It 
would  be  unjust  to  Davy  to  put  our  knowledge  in  the 
place  of  his,  or  to  credit  him  with  data  which  he  could 
not  have  possessed.  Rumor  and  fact  had  connected  the 
name  of  Wollaston  with  these  supposed  interactions  between 
magnets  and  currents.  When,  therefore,  Faraday  in 
October  published  his  successful  experiment,  without  any 
allusion  to  Wollaston,  general,  though  really  ungrounded, 
criticism  followed.  I  say  ungrounded  because,  firstly, 
Faraday's  experiment  was  not  that  of  Wollaston,  and  sec- 
ondly, Faraday,  before  he  published  it,  had  actually  called 
upon  Wollaston,  and  not  finding  him  at  home,  did  not 
feel  himself  authorized  to  mention  his  name. 

In  December,  Faraday  published  a  second  paper  on  the 
same  subject,  from  which,  through  a  misapprehension, 
the  name  of  Wollaston  was  also  omitted.  Warburtou  and. 
others  thereupon  affirmed  that  Wollaston's  ideas  had  been 
appropriated  without  acknowledgment,  and  it  is  plain 
that  Wollaston  himself,  though  cautious  in  his  utterance, 
was  also  hurt.  Censure  grew  till  it  became  intolerable. 
''I  hear,"  writes  Faraday  to  his  friend  Stodart,  "every 
day  more  and  more  of  these  sounds,  which,  though  only 
whispers  to  me,  are,  I  suspect,  spoken  aloud  among  scien- 
tific men."  He  might  have  written  explanations  and  de- 
fenses, but  he  went  straighter  to  the  point.  He  wished  to 
see  the  principals  face  to  face — to  plead  his  cause  before 
them  personally.  There  was  a  certain  vehemence  in  hia 
desire  to  do  this.  He  saw  Wollaston,  he  saw  Davy,  he  saw 
Warburtou;  and  I  am  inclined  to  think  that  it  was  the 
irresistible  candor  and,  truth  of  character  which  tkeso 


310  FRAGMENTS  OF  SCIENCE. 

vivd  voce  defenses  revealed,  as  much  as  the  defenses  them- 
selves, that  disarmed  resentment  at  the  time. 

As  regards  Davy,  another  cause  of  dissension  arose  in 
1823.  In  the  spring  of  that  year  Faraday  analyzed  the 
hydrate  of  chlorine,  a  substance  once  believed  to  be  the 
element  chlorine,  but  proved  by  Davy  to  be  a  compound  of 
that  element  and  water.  The  analysis  was  looked  over  by 
Davy,  who  then  and  the're  suggested  to  Faraday  to  heat  the 
hydrate  in  a  closed  glass  tube.  This  was  done,  the  sub- 
stance was  decomposed,  and  one  of  the  products  of  decom- 
position was  proved  by  Faraday  to  be  chlorine  liquefied  by 
its  own  pressure.  On  the  day  of  its  discovery  he  communi- 
cated this  result  to  Dr.  Paris.  Davy,  on  being  informed 
of  it,  instantly  liquefied  another  gas  in  the  same  way. 
Having  struck  thus  into  Faraday's  inquiry,  ought  he  not  to 
have  left  the  matter  in  Faraday's  hands?  I  think  he 
ought.  But,  considering  his  relation  to  both  Faraday  and- 
the  hydrate  of  chlorine,  Davy,  I  submit,  may  be  excused 
for  thinking  differently.  A  father  is  not  always  wise 
enough  to  see  that  his  son  has  ceased  to  be  a  boy,  and 
estrangement  on  this  account  is  not  rare;  nor  was  Davy 
wise  enough  to  discern  that  Faraday  had  passed  the  mere 
assistant  stage,  and  become  a  discoverer.  It  is  now  hard  to 
avoid  magnifying  this  error.  But  hail  Faraday  died  or 
ceased  to  work  at  this  time,  or  had  his  subsequent  life  been 
devoted  to  money-getting,  instead  of  to  research,  would 
anybody  now  dream  of  ascribing  jealousy  to  Davy?  Assur- 
edly not.  Why  should  he  be  jealous?  His  reputation  at 
this  time  was  almost  without  a  parallel;  his  glory  was  with- 
out a  cloud.  He  had  added  to  his  other  discoveries  that 
of  Faraday,  and  after  having  been  his  teacher  for  seven 
years,  his  language  to  him  was  this:  "  It  gives  me  great 
pleasure  to  hear  that  you  are  comfortable  at  the  Royal 
Institution,  and  I  trust  that  you  will  not  only  do  something 
good  and  honorable  for  yourself,  but  also  for  science." 
This  is  not  the  language  of  jealousy,  potential  or  actual. 
But  the  chlorine  business  introduced  irritation  and  anger, 
to  which,  and  not  to  any  ignobler  motive,  Daw's  oppo- 
sition to  the  election  of  Faraday  to  the  Royal  Society  is,  I 
am  persuaded,  to  be  ascribed. 

These  matters  are  touched  upon  with  perfect  candor, 
and  becoming  consideration,  in  the  volumes  of  Dr.  Bence 
Jones;  but  in  "society"  they  are  not  always  so  handled. 


LIFE  AND  LETTERS  OF  FAR  AD  A  T.  31 1 

Here  a  name  of  noble  intellectual  associations  is  sur- 
rounded by  injurious  rumors  which  I  would  willingly  scatter 
forever.  The  pupil's  magnitude,  and  the  splendor  of  his 
position,  are  too  great  and  absolute  to  need  as  a  foil  the 
humiliation  of  his  master.  Brothers  in  intellect,  Davy  and 
Faraday,  however,  could  never  have  become  brothers  in 
feeling;  their  characters  were  too  unlike.  Davy  loved  the 
pomp  and  circumstance  of  fame;  Faraday  the  inner  con- 
sciousness that  he  had  fairly  won  renown.  They  were  both 
proud  men.  But  with  Davy  pride  projected  itself  into  the 
outer  world;  while  with  Faraday  it  became  a  steadying  and 
dignifying  inward  force.  In  one  great  particular  they 
agreed.  Each  of  them  could  have  turned  his  science  to 
immense  commercial  profit,  but  neither  of  them  did  so. 
The  noble  excitement  of  research,  and  the  delight  of  dis- 
covery, constituted  their  reward.  I  commend  them  to  the 
reverence  which  great  gifts  greatly  exercised  ought  to  in- 
spire. They  were  botli  ours;  and  through  the  coming  cen- 
turies England  will  be  able  to  point  with  just  pride  to  the 
possession  of  such  men. 


The  first  volume  of  the  "  Life  and  Letters  "  reveals  to 
us  the  youth  who  was  to  be  father  to  the  man.  Skillful, 
aspiring,  resolute,  he  grew  steadily  in  knowledge  and  in 
power.  Consciously  or  unconsciously,  the  relation  of 
Action  to  Reaction  was  ever  present  to  Faraday's  mind.  It 
had  been  fostered  by  his  discovery  of  Magnetic  Rotations, 
and  it  planted  in  him  more  daring  ideas  of  a  similar  kind. 
Magnetism  he  knew  could  be  evoked  by  electricity,  and  he 
thought  that  electricity,  in  its  turn,  ought  to  be  capable  of 
evolution  by  magnetism.  On  August  29,  1831,  his  experi- 
ments on  this  subject  began.  He  had  been  fortified  by 
previous  trials,  which,  though  failures,  had  begotten 
instincts  directing  him  toward  the  truth.  He,  like  every 
strong  worker,  might  at  times  miss  the  outward  object,  but 
he  always  gained  the  inner  light,  education,  and  expansion. 
Of  this  Faraday's  life  was  a  constant  illustration.  By 
November  he  had  discovered  and  colligated  a  multitude  of 
the  most  wonderful  and  unexpected  phenomena.  He  had 
generated  currents  by  currents;  currents  by  magnets,  per- 
manent and  transitory;  and  he  afterward  generated  cur- 
rents by  the  earth  itself.  Arago's  "Magnetism  of  Rotation/' 


312  FRAGMENTS  OF  SCIENCE. 

which  had  for  years  offered  itself  as  a  challenge  to  the  best 
scientific  intellects  of  Europe,  now  fell  into  his  hands.  It 
proved  to  be  a  beautiful,  but  still  special,  illustration  of  the 
great  principle  of  Magneto-electric  Induction.  Nothing 
equal  to  this  latter,  in  the  way  of  pure  experimental  in- 
quiry, had  previously  been  achieved. 

Electricities  from  various  sources  were  next  examined, 
and  their  differences  and  resemblances  revealed.  He  thus 
assured  himself  of  their  substantial  identity.  He  then  took 
up  Conduction,  and  gave  many  striking  illustrations  of  the 
influence  of  Fusion  on  Conducting  Power.  Renouncing 
professional  work,  from  which  at  this  time  he  might  have 
derived  an  income  of  many  thousands  a  year,  he  poured 
his  whole  momentum  into  his  researches.  He  was  long 
entangled  in  Electro-chemistry.  The  light  of  law  was  for 
a  time  obscured  by  the  thick  umbrage  of  novel  facts;  but 
he  finally  energed  from  his  researches  with  the  great  prin- 
ciple of  Definite  Electro-chemical  Decomposition  in  his 
hands.  If  his  discovery  of  Magneto-electricity  may  be 
ranked  with  that  of  the  pile  by  Volta,  this  new  discoverv 
may  almost  stand  beside  that  of  Definite  Combining  Pro- 
portions in  Chemistry.  He  passed  on  to  Static  Electricity 
— its  Conduction,  Induction,  and  mode  of  Propagation. 
He  discovered  and  illustrated  the  principle  of  Inductive 
Capacity;  and,  turning  to  theory,  he  asked  himself  how 
electrical  attractions  and  repulsions  are  transmitted.  Are 
they,  like  gravity,  actions  at  a  distance,  or  do  they  require 
a  medium?  If  the  former,  then,  like  gravity,  they  will  act 
in  straight  lines;  if  the  latter,  then,  like  sound  or  light, 
they  may  turn  a  corner.  Faraday  held — and  his  views  are 
gaining  ground — that  his  experiments  proved  the  fact  of 
curvilinear  propagation,  and  hence  the  operation  of  a 
medium.  Others  denied  this;  but  none  can  deny  the  pro- 
found and  philosophic  character  of  his  leading  thought.  * 
The  first  volume  of  the  Researches  contains  all  the  papers 
here  referred  to. 

Faraday  had  heard  it  stated  that  henceforth  physical 
discoveries  would  be  made  solely  by  the  aid  of  mathematics; 
that  we  had  our  data,  and  needed  only  to  work  deductively. 
Statements  of  a  similar  character  crop  out  from  time  to  time 

*  In  a  very  remarkable  paper  published  in  Poggendorff's  "An- 
nalen"  for  1857,  Werner  Siemens  accepts  and  develops  Faraday's 
theory  of  Molecular  Induction. 


LIFE  AND  LETTERS  OF  FA  RAD  A  T.  313 

in  our  day.  They  arise  from  an  imperfect  acquaintance  with 
the  nature,  present  condition,  and  prospective  vastness  of 
the  field  of  physical  inquiry.  The  tendency  of  natural 
science  doubtless  is  to  bring  all  physical  phenomena  under 
the  dominion  of  mechanical  laws;  to  give  them,  in  other 
words,  mathematical  expression.  But  our  approach  to 
this  result  is  asymptotic;  and  for  ages  to  come — possibly 
for  all  the  ages  of  the  human  race — Nature  will  find  room 
for  both  the  philosophical  experimenter  and  the  mathe- 
matician. Faraday  entered  his  protest  against  the  fore- 
going statement  by  labeling  his  investigations  "  Experi- 
mental Researches  in  Electricity."  They  were  completed 
in  1854,  and  three  volumes  of  them  have  been  published. 
For  the  sake  of  reference,  he  numbered  every  paragraph, 
the  last  number  being  3,362.  In  1859  he  collected  and 
published  a  fourth  volume  of  papers,  under  the  title, 
"Experimental  Researches  in  Chemistry  and  Physics." 
Thus  did  this  apostle  of  experiment  illustrate  its  power, 
and  magnify  his  office. 

The  second  volume  of  the  Researches  embraces  memoirs 
on  the  Electricity  o'f  the  Gymnotus;  on  the  Source  of 
Power  in  the  Voltaic  Pile;  on  the  Electricity  evolved  by  the 
Friction  of  Water  and  Steam,  in  which  the  phenomena  and 
principles  of  Sir  William  Armstrong's  Hydro-electric  ma- 
chineare  described  and  developed;  a  paper  on  Magnetic  Rota- 
tions, and  Faraday's  letters  in  relation  to  the  controversy 
it  aroused.  The  contribution  of  most  permanent  value 
here,  is  that  on  the  Source  of  Power  in  the  Voltaic  Pile. 
By  it  the  Contact  Theory,  pure  and  simple,  was  totally 
overthrown,  and  the  necessity  of  chemical  action  to  the 
maintenance  of  the  current  demonstrated. 

The  third  volume  of  the  Researches  opens  with  a  memoir 
entitled  "The  Magnetization  of  Light,"  and  the  "Illu- 
mination of  Magnetic  Lines  of  Force."  It  is  difficult  even 
now  to  affix  a  definite  meaning  to  this  title;  but  the  dis- 
covery of  the  rotation  of  the  plane  of  polarization,  which  it 
announced,  seems  pregnant  with  great  results.  The  writ- 
ings of  William  Thomson  on  the  theoretic  aspects  of  the 
discovery;  the  excellent  electro-dynamic  measurements  of 
Wilhelm  Weber,  which  are  models  of  experimental  com- 
pleteness and  skill;  Weber's  labors  in  conjunction  with  his 
lamented  friend  Kohlrausch — above  all,  the  researches  of 
Clerk  Maxwell  on  the  Electro-magnetic  Theory  of  Light — > 


314  FRAGMENTS  OF  SCIENCE. 

point  to  that  wonderful  and  mysterious  medium,  which  is 
the  vehicle  of  light  and  radiant  heat,  as  the  probable  basis 
also  of  magnetic  and  electric  phenomena.  The  hope  of 
such  a  connection  was  first  raised  by  the  discovery  here 
referred  to.*  Faraday  himself  seemed  to  cling  with  par- 
ticular affection  to  this  discovery.  He  felt  that  there  was 
more  in  it  than  he  was  able  to  unfold.  He  predicted  that 
it  would  grow  in  meaning  with  the  growth  of  science. 
This  it  has  done;  this  it  is  doing  now.  Its  right  inter- 
pretation will  probably  mark  an  epoch  in  scientific  history. 

Rapidly  following  it  is  the  discovery  of  Diamagnetism, 
or  the  repulsion  of  matter  by  a  magnet.  Brugmans  had 
shown  that  bismuth  repelled  a  magnetic  needle.  Here  he 
stopped.  Le  Bailliff  proved  that  antimony  did  the  same. 
Here  he  stopped.  Seebeck,  Becquerel,  and  others,  also 
touched  the  discovery.  These  fragmentary  gleams  excited 
a  momentary  curiosity  and  were  almost  forgotten,  when 
Faraday  independently  alighted  on  the  same  facts:  and, 
instead  of  stopping,  made  them  the  inlets  to  a  new  and 
vast  region  of  research.  The  value  of  a  discovery  is  to  be 
measured  by  the  intellectual  action  it  calls  forth;  and  it 
was  Faraday's  good  fortune  to  strike  such  lodes  of  scientific 
truth  as  give  occupation  to  some  of  the  best  intellects  of 
our  age. 

The  salient  quality  of  Faraday's  scientific  character 
reveals  itself  from  beginning  to  end  of  these  volumes;  a 
union  of  ardor  and  patience — the  one  prompting  the  attack, 
the  other  holding  him  on  to  it,  till  defeat  was  final  or  vic- 
tory assured.  Certainty  in  one  sense  or  the  other  was 
necessary  to  his  peace  of  mind.  The  right  method  of  in- 
vestigation is  perhaps  incommunicable;  it  depends  on  the 
individual  rather  than  on  the  system,  and  the  mark  is 
missed  when  Faraday's  researches  are  pointed  to  as  merely 

*  A  letter  addressed  to  me  by  Professor  Weber  oil  March  18th  last 
contains  the  following  reference  to  the  connection  here  mentioned: 
"  Die  Hoffnung  einer  solchen  Combination  ist  durch  Faraday's 
Entdeckung  der  Drehiing  der  Polarisationsebene  durch  magnetische 
Directionskraft  zuerst,  und  sodann  durch  die  Uebereinstimmung  der- 
jenigen  Geschwindigkeit,  welche  das  Verhaltniss  der  electro- 
dynamischen  Einheit  -zur  electro-statischen  ausdriickt,  mit  der 
Geschwindigkeit  des  Lichts  angeregt  worden;  und  mir  scheint  von 
alien  Versuchen,  welche  zur  Verwirklichung  dieser  Hoffnung  ge- 
macht  worden  sind,  das  von  Herrn  Maxwell  getuachte  am  erfol- 
greichsteu." 


LIFE  AND  LETTERS  OF  FARAD  A  T.  315 

illustrative  of  the  power  of  the  inductive  philosophy.  The 
brain  may  be  filled  with  that  philosophy;  but  without  the 
energy  and  insight  which  this  man  possessed,  and  which 
with  him  were  personal  and  distinctive,  we  should  never 
rise  to  the  level  of  his  achievements.  His  power  is  that  of 
individual  genius,  rather  than  of  philosophical  method;  the 
energy  of  a  strong  soul  expressing  itself  after  its  own 
fashion,  and  acknowledging  no  mediator  between  it  and 
Nature. 

The  second  volume  of  the  "  Life  and  Letters,"  like  the 
first,  is  a  historic  treasury  as  regards  Faraday's  work  and 
character,  and  his  scientific  and  social  relations.  It  con- 
tains letters  from  Humboldt,  Herschel,  Hachette,  De  la 
Eive,  Dumas,  Liebig,  Melloni,  Becquerel,  Oersted,  Pliicker, 
Du  Bois-Reymoud,  Lord  Melbourne,  Prince  Louis  Napo- 
leon, and  many  other  distinguished  men.  I  notice  with 
particular  pleasure  a  letter  from  Sir  John  Herschel,  in 
reply  to  a  sealed  packet  addressed  to  him  by  Faraday,  but 
which  he  had  permission  to  open  if  he  pleased.  The 
packet  referred  to  one  of  the  many  unfulfilled  hopes  which 
spring  up  in  the  minds  of  fertile  investigators: 

"  Go  on  and  prosper,  'from  strength  to  strength,' like 
a  victor  inarching,  with  assured  step  to  further  conquests; 
and  be  certain  that  no  voice  will  join  more  heartily  in  the 
peans  that  already  begin  to  rise,  and  will  speedily  swell 
into  a  shout  of  triumph,  astounding  even  to  yourself,  than 
that  of  J.  F.  W.  Herschel." 

Faraday's  behavior  to  Melloni  in  1835  merits  a  word  of1 
notice.  The  young  man  was  a  political  exile  in  Paris. 
He  had  newly  fashioned  and  applied  the  thermo-electric 
pile,  and  had  obtained  with  it  results  of  the  greatest  im- 
portance. But  they  were  not  appreciated.  With  the 
sickness  of  disappointed  hope  Melloni  waited  for  the  re- 
port of  the  commissioners,  appointed  by  the  Academy  of 
Sciences  to  examine  the  primier.  At  length  he  published 
his  researches  in  the  "  Annales  de  Chimie."  They  thus 
fell  into  the  hands  of  Faraday,  who,  discerning  at  once 
their  extraordinary  merit,  obtained  for  their  author  the 
Rum  ford  Medal  of  the  Royal  Society.  A  sum  of  money 
always  accompanies  this  medal;  and  the  pecuniary  help 
was,  at  this  time,  even  more  essential  than  the  mark  of 
honor  to  the  young  refugee.  Melloni's  gratitude  was 
boundless; 


316  FRAGMENTS  OF  SCIENCE. 

"  Et  vous,  monsieur/'  he  writes  to  Faraday,  "  qui  ap- 
parteuez  a  une  societe  a  laquelle  je  n'avaisrien  offert,  vous 
qui  me  conuaissiez  a  peine  de  nom;  vous  u'avez  pas  <3e- 
mandesi  j'avaisdesennemis  faibles  ou  puissants,  ni  calcule 
quel  en  etait  le  notnbre;  mais  vousavez  parle  pour  1'opprime 
Stranger,  pour  celui  qui  n'avait  pas  le  moindre  droit  a  taut 
de  bienveillance,  et  vos  paroles  out  ete  accueillies  favorable- 
ment  par  des  collegues  conscieucieux!  Je  reconnais  bien 
la  des  hommes  dignes  de  leur  noble  mission,  les  veritable 
representants  de  la  science  d'un  pays  libre  et  genereux." 

Within  the  prescribed  limits  of  this  article  it  would  be 
impossible  to  give  even  the  slenderest  summary  of  Faraday's 
correspondence,  or  to  carve  from  it  more  than  the  merest 
fragments  of  his  character.  His  letters,  written  to  Lord 
Melbourne  and  others  in  1836,  regarding  his  pension,  illus- 
trate his  uncompromising  independence.  The  prime  min- 
ister had  offended  him,  but  assuredly  the  apology  demanded 
and  given  was  complete.  I  think  it  certain  that,  notwith- 
standing the  very  full  account  of  this  transaction  given  by 
Dr.  Bence  Jones,  motives  and  influences  were  at  work 
which  even  now  are  not  entirely  revealed.  The  minister  was 
bitterly  attacked,  but  he  bore  the  censure  of  the  press  with 
great  dignity.  Faraday,  while  he  disavowed  having  either 
directly  or  indirectly  furnished  the  matter  of  those  attacks, 
did  not  publicly  exonerate  the  primier.  The  Hon.  Caro- 
line Fox  had  proved  herself  Faraday's  ardent  friend,  and 
it  was  she  who  had  healed  the  breach  between  the  phi- 
losopher and  the  minister.  She  manifestly  thought  that 
Faraday  ought  to  have  come  forward  in  Lord  Melbourne's 
defense,  and  there  is  a  flavor  of  resentment  in  one  of  her 
letters  to  him  on  the  subject.  No  doubt  Faraday  had  good 
grounds  for  his  reticence,  but  they  are  to  me  unknown. 

In  1841  his  health  broke  down  utterly,  and  he  went  to 
Switzerland  with  his  wife  and  brother-in-law.  His  bodily 
vigor  soon  revived,  and  he  accomplished  feats  of  walking 
respectable  even  for  a  trained  mountaineer.  The  published 
extracts  from  his  Swiss  journal  contain  many  beautiful 
and  touching  allusions.  Amid  references  to  the  tints  of 
the  Jungfrau,  the  blue  rifts  of  the  glaciers,  and  the  noble 
Niesen  towering  over  the  lake  of  Thun,  we  come  upon 
the  charming  little  scrap  which  I  have  elsewhere  quoted: 
"  Clout-nail  making  goes  on  here  rather  considerably,  and 
is  a  very  neat  and  pretty  operation  to  observe.  I  love  a, 


LIPS!  AND  LETTERS  OF  FARADAY.  31 7 

Smith's  shop  and  anything  relating  to  smithery.  My  father 
was  a  smith."  This  is  from  his  journal;  but  he  is  uncon- 
sciously speaking  to  somebody — perhaps  to  the  world. 

His  description  of  the  Staubbach,  Giessbach,  and  of  the 
scenic  effects  of  sky  and  mountain,  are  all  fine  and  sympa- 
thetic. But  amid  it  all,  and  in  reference  to  it  all,  he  tells 
his  sister  that  "  true  enjoyment  is  from  within,  not  from 
without."  In  those  days  Agassiz  was  living  under  a  slab 
of  gneiss  on  the  glacier  of  the  Aar.  Faraday  met  Forbes 
at  the  Grimsel,  and  arranged  with  him  an  excursion  to 
the  "  Hotel  des  Neuchtelaois;"  but  indisposition  put  the 
project  out. 

From  the  Fort  of  Ham,  in  1843,  Faraday  received  a 
letter  addressed  to  him  by  Prince  Louis  Napoleon  Bona- 
parte. He  read  this  letter  to  me  many  years  ago,  and  the 
desire,  shown  in  various  ways  by  the  French  emperor,  to 
turn  modern  science  to  account,  has  often  reminded  me  of 
it  since.  At  the  age  of  thirty-five  the  prisoner  of  Ham 
speaks  of  "  rendering  his  captivity  less  sad  by  studying  the 
great  discoveries"  which  science  owes  to  Faraday;  and  he 
asks  a  question  which  reveals  his  cast  of  thought  at  the 
time:  "  What  is  the  most  simple  combination  to  give  to  a 
voltaic  battery,  in  order  to  produce  a  spark  capable  of  set- 
ting fire  to  powder  under  water  or  under  ground?" 
Should  the  necessity  arise,  the  French  emperor  will  not 
lack  at  the  outset  the  best  appliances  of  modern  science; 
while  we,  I  fear,  shall  have  to  learn  the  magnitude  of  the 
resources  we  are  now  neglecting  amid  the  pangs  of  actual 
war.* 

One  turns  with  renewed  pleasure  to  Faraday's  letters  to 
his  wife,  published  in  the  second  volume.  Here  surely  the 
loving  essence  of  the  man  appears  more  distinctly  than  any- 
where else.  From  the  house  of  Dr.  Percy,  in  Birmingham, 
he  writes  thus: 

"  Here — even  here — the  moment  I  leave  the  table,  I  wish 
I  were  with  you  iis"  QUIET.  Oh,  what  happiness  is  ours! 
My  runs  into  the  world  in  this  way  only  serve  to  make  me 
esteem  that  happiness  the  more." 

*The  "science"  has  since  been  applied,  with  astonishing  effect , 
by  those  who  had  studied  it  far  more  thoroughly  than  the  emperor  of 
the  French.  We  also,  I  am  happy  to  think,  have  improved  the  time 
since  the  above  words  were  written  [1878]. 


518  FRAGMENTS  Off  SCIENCE. 

And  again: 

"  We  have  been  to  a  grand  conversazione  in  the  town 
hall,  and  I  have  now  returned  to  my  room  to  talk  with  you, 
as  the  pleasantest  and  happiest  thing  that  I  can  do.  Noth- 
ing rests  rne  so  much  as  communion  with  you.  I  feel  it 
even  now  as  I  write,  and  catch  myself  saying  the  words 
aloud  as  I  write  them."  Take  this,  moreover,  as  indicative 
of  his  love  for  Nature: 

"After  writing,  I  walk  out  in  the  evening  hand  in  hand 
with  my  dear  wife  to  enjoy  the  sunset;  for  to  me  who  love 
scenery,  of  all  that  I  have  seen  or  can  see,  there  is  none 
surpasses  that  of  heaven.  A  glorious  sunset  brings  with  it 
a  thousand  thoughts  that  delight  me." 

Of  the  numberless  lights  thrown  upon  him  by  the  "  Life 
and  Letters "  some  fall  upon  his  religion.  In  a  letter  to 
Lady  Lovelace,  he  describes  himself  as  belonging  to  "a 
very  small  and  despised  sect  of  Christians,  known,  if 
known  at  all,  as  Sandemanians,  and  our  hope  is  founded 
on  the  faith  that  is  in  Christ."  He  adds:  "  I  do  not  think 
it  at  all  necessary  to  tie  the  study  of  the  natural  sciences  and 
religion  together,  and  in  my  intercourse  with  my  fellow- 
creatures,  that  which  is  religious,  and  that  which  is  phi- 
losophical, have  ever  been  two  distinct  things."  He  saw 
clearly  the  danger  of  quitting  his  moorings,  and  his  science 
acted  indirectly  as  the  safeguard  of  his  faith.  For  his  in- 
vestigations so  filled  his  mind  as  to  leave  no  room  for 
skeptical  questionings,  thus  shielding  from  the  assaults  of 
philosophy  the  creed  of  his  youth.  His  religion  was 
constitutional  and  hereditary.  It  was  implied  in  the  eddies 
of  his  blood  and  in  the  tremors  of  his  brain;  and,  however  its 
outward  and  visible  form  might  have  changed,  Faraday 
would  still  have  possessed  its  elemental  constituents — awe, 
reverence,  truth,  and  love. 

It  is  worth  inquiring  how  so  profoundly  religious  a 
mind,  and  so  great  a  teacher,  would  be  likely  to  regard  our 
present  discussions  on  the  subject  of  education.  Faraday 
would  be  a  "  secularist "  were  he  now  alive.  He  had  no 
sympathy  with  those  who  contemn  knowledge  unless  it  be 
accompanied  by  dogma.  A  lecture  delivered  before  the 
City  Philosophical  Society  in  1818,  when  he  was  twenty- 
six  years  of  age,  expresses  the  views  regarding  education 
which  he  entertained  to  the  end  of  his  life.  "  First,  then," 
he  says,  "all  theological  considerations  are  banished  from 


LIFE  AND  LETTERS  OF  FARADAY.  319 

the  society,  and  of  course  from  my  remarks;  and  whatever 
I  may  say  has  110  reference  to  a  future  state,  or  to  the 
means  which  are  to  be  adopted  in  this  world  in  anticipation 
of  it.  Next,  I  have  no  intention  of  substituting  anything 
for  religion,  but  I  wish  to  take  that  part  of  human  nature 
which  is  independent  of  it.  Morality,  pliilosophy,  commerce, 
the  various  institutions  and  habits  of  society,  are  independ- 
ent of  religion,  and  may  exist  either  with  or  without  it. 
They  are  always  the  same,  and  can  dwell -alike  in  the 
breasts  of  those  who,  from  opinion,  are  entirely  opposed  in 
the  set  of  principles  they  include  in  the  term  religion,  or 
in  those  who  have  none. 

"  To  discriminate  more  closely,  if  possible,  I  will  observe 
that  we  have  no  right  to  judge  religions  opinions;  but  the 
human  nature  of  this  evening  is  that  part  of  man  which 
we  have  a  right  to  judge.  And  I  think  it  will  be  found  on 
examination,  that  this  humanity — as  it  may  perhaps  be 
called — will  accord  with  what  I  have  before  described  as 
being  in  our  own  hands  so  improvable  and  perfectible." 

In  an  old  journal  I  find  the  following  remarks  on  one  of 
rny  earliest  dinners  with  Faraday:  "  At  two  o'clock  he  came 
down  for  me.  He,  his  niece,  and  myself,  formed  the  party. 
'  I  never  give  dinners/  he  said.  '  I  don't  know  how  to 
give  dinners,  and  I  never  dine  out.  But  I  should  not  like 
my  friends  to  attribute  this  to  a  wrong  cause.  I  act  thus 
for  the  sake  of  securing  time  for  work,  and  not  through 
religious  motives,  as  some  imagine/  He  said  grace.  I  am 
almost  ashamed  to  call  his  prayer  a 'saying  of  grace.'  In 
the  language  of  Scripture,  it  might  be  described  as  the 
petition  of  a  sou,  into  whose  heart  God  had  sent  the  Spirit 
of  His  Son,  and  who  with  absolute  trust  asked  a  blessing 
from  his  father.  We  dined  on  roast  beef,  Yorkshire  pud- 
ding, and  potatoes;  drank  sherry,  talked  of  research  and 
its  requirements,  and  of  his  habit  of  keeping  himself  free 
from  the  distractions  of  society.  He  was  bright  and  joy- 
ful— boy-like,  in  fact,  though  he  is  now  sixty-two.  His 
work  excites  admiration,  but  contact  with  him  warms  and 
elevates  the  heart.  Here,  surely,  is  a  strong  man.  I  love 
strength;  but  let  me  not  forget  the  example  of  its  union 
with  modesty,  tenderness,  and  sweetness,  in  the  character 
of  Faraday." 

Faraday's  progress  in  discovery,  and  the  salient  points 
of  his  character,  are  well  brought  out  by  the  wise  choice 


320  FSA  GMENTS  OF  SCIENCE. 

of  letters  and  extracts  published  in  the  volumes  before  us. 
I  will  not  call  the  labors  of  the  biographer  final.  So  great 
a  character  will  challenge  reconstruction.  In  the  coming 
time  some  sympathetic  spirit,  with  the  requisite  strength, 
knowledge,  and  solvent  power,  will,  I  doubt  not,  render 
these  materials  plastic,  give  them  more  perfect  organic 
form,  and  send  through  them,  with  less  of  interruption, 
the  currents  of  Faraday's  life.  "  He  was  too  good  a  man," 
writes  his  present  biographer,  "for  me  to  estimate  rightly, 
and  too  great  a  philosopher  for  me  to  understand 
thoroughly."  That  may  be:  but  the  reverent  affection  to 
which  we  owe  the  discovery,  selection,  and  arrangement  of 
the  materials  here  placed  before  us,  is  probably  a  surer 
guide  than  mere  literary  skill.  The  task  of  the  artist  who 
may  wish  in  future  times  to  reproduce  the  real  though 
unobtrusive  grandeur,  the  purity,  beauty,  and  childlike 
simplicity  of  him  whom  we  have  lost,  will  find  his  chief 
treasury  already  provided  for  him  by  Dr.  Bence  Jones' 
labor  of  love. 


CHAPTER  XIX. 

THE   COPLEY   MEDALIST   OF   1870. 

THIRTY  years  ago  Electro-magnetism  was  looked  to  as  a 
motive  power,  which  might  possibly  compete  with  steam. 
In  the  centers  of  industry,  such  as  Manchester,  attempts  to 
investigate  and  apply  this  power  were  numerous.  This  is 
shown  by  the  scientific  literature  of  the  time.  Among 
others  Mr.  James  Prescot  Joule,  a  resident  of  Manchester, 
took  up  the  subject,  and,  in  a  series  of  papers  published  in 
Sturgeon's  "  Annals  of  Electricity"  between  1839  and  1841, 
described  various  attempts  at  the  construction  and  per- 
fection of  electro-magnetic  engines.  The  spirit  in  which 
Mr.  Joule  pursued  these  inquiries  is  revealed  in  the  fol- 
lowing extract:  "I  am  particularly  anxious,"  he  says,  "to 
communicate  any  new  arrangement  in  order,  if  possible,  to 
forestall  the  monopolizing  designs  of  those  who  seem  to 
regard  this  most  interesting  subject  merely  in  the  light  of 
pecuniary  speculation."  He  was  naturally  led  to  investi- 
gate the  laws  of  electro-magnetic  attractions,  and  in  1840 
he  announced  the  important  principle  that  the  attractive 
force  exerted  by  two  electro-magnets,  or  by  an  electro- 


THE  COPLEY  MEDALIST  OF  1871.  321 

magnet  and  a  mass  of  annealed  iron,  is  directly  propor- 
tional to  the  square  of  the  strength  of  the  magnetizing 
current;  while  the  attraction  exerted  between  an  electro- 
magnet and  the  pole  of  a  permanent  steel  magnet  varies 
simply  as  the  strength  of  the  current.  These  investiga- 
tions were  conducted  independently  of,  though  a  little 
subsequently  to  the  celebrated  inquiries  of  Henry,  Jacobi, 
and  Lenz  and  Jacobi,  on  the  same  subject. 

On  December  17,  1840,  Mr.  Joule  communicated  to  the 
Royal  Society  a  paper  on  the  production  of  heat  by  Voltaic 
electricity.  In  it  he  announced  the  law  that  the  calorific 
effects  of  equal  quantities  of  transmitted  electricity  are 
proportional  to  the  resistance  overcome  by  the  current, 
whatever  may  be  the  length,  thickness,  shape,  or  character 
of  the  metal  which  closes  the  circuit;  and  also  propor- 
tional to  the  square  of  the  quantity  of  transmitted 
electricity.  This  is  a  law  of  primary  importance.  In 
another  paper,  presented  to,  but  declined  by  the  Royal 
Society,  he  confirmed  this  law  by  new  experiments,  and 
materially  extended  it.  He  also  executed  experiments  on 
the  heat  consequent  on  the  passage  of  Voltaic  electricity 
through  electrolytes,  and  found,  in  all  cases,  that  the  heat 
evolved  by  the  proper  action  of  any  Voltaic  current  is  pro- 
portional to  the  square  of  the  intensity  of  that  current, 
multiplied  by  the  resistance  to  conduction  which  it 
experiences.  From  this  law  he  deduced  a  number  of  con- 
clusions of  the  highest  importance  to  electro-chemistry. 

It  was  during  these  inquiries,  which  are  marked  through- 
out by  rare  sagacity  and  originality,  that  the  great  idea  of 
establishing  quantitative  relations  between  Mechanical 
Energy  and  Heat  arose  and  assumed  definite  form  in  his 
mind.  In  1843  Mr.  Joule  read  before  the  meeting  of  the 
British  Association  at  Cork  a  paper  "  On  the  Calorific 
Effects  of  Magneto-Electricity,  and  on  the  Mechanical 
Value  of  Heat."  Even  at  the  present  day  this  memoir  is 
tough  reading,  and  at  the  time  it  was  written  it  must  have 
appeared  hopelessly  entangled.  This,  I  should  think,  was 
the  reason  why  Faraday  advised  Mr.  Joule  not  to  submit 
the  paper  to  the  Royal  Society.  But  its  drift  and  results 
are  summed  up  in  these  memorable  words  by  the  author, 
written  some  time  subsequently:  "In  that  paper  it  was 
demonstrated  experimentally,  that  the  mechanical  power 
exerted  in  turning  a  magneto-electric  machine  is  converted. 


322  FRAGMENTS  OF  SCIENCE. 

into  the  heat  evolved  by  the  passage  of  the  currents  of  in- 
duction through  its  coils;  and,  on  the  other  hand,  that 
the  motive  power  of  the  electro-magnetic  engine  is  obtained 
at  the  expense  of  the  heat  due  to  the  chemical  reaction  of 
the  battery  by  which  it  is  worked."*  It  is  needless  to 
dwell  upon  the  weight  and  importance  of  this  statement. 

Considering  the  imperfections  incidental  to  a  first 
determination,  it  is  not  surprising  that  the  "  mechanical 
values  of  heat,"  deduced  from  the  different  series  of  ex- 
periments published  in  1843,  varied  widely  from  each 
other.  The  lowest  limit  was  587,  and  the  highest  1,026 
foot-pounds,  for  one  degree  Fahrenheit  of  temperature. 

One  noteworthy  result  of  his  inquiries,  which  was 
pointed  out  at  the  time  by  Mr.  Joule,  had  reference  to 
the  exceedingly  small  fraction  of  the  heat  actually  con- 
verted into  useful  effect  in  the  steam-engine.  The 
thoughts  of  the  celebrated  Julius  Robert  Mayer,  who  was 
then  engaged  in  Germany  upon  the  same  question,  had 
moved  independently  in  the  same  groove;  but  to  his 
labors  due  reference  will  be  made  on  a  future  occasion. f 
In  the  memoir  now  referred  to,  Mr.  Joule  also  announced 
that  he  had  proved  heat  to  be  evolved  during  the 
passage  of  water  through  narrow  tubes;  and  he  deduced 
from  these  experiments  an  equivalent  of  770  foot-pounds,  a 
figure  remarkably  near  the  one  now  accepted.  A  detached 
statement  regarding  the  origin  and  convertibility  of  animal 
heat  strikingly  illustrates  the  penetration  of  Mr.  Joule, 
and  his  mastery  of  principles,  at  the  period  now  referred 
to.  A  friend  had  mentioned  to  him  Haller's  hypothesis, 
that  animal  heat  might  arise  from  the  friction  of  the  blood 
in  the  veins  and  arteries.  "  It  is  unquestionable,"  writes 
Mr.  Joule,  "  that  heat  is  produced  by  such  friction;  but  it 
must  be  understood  that  the  mechanical  force  expended  in 
the  friction  is  a  part  of  the  force  of  affinity  which  causes 
the  venous  blood  to  unite  with  oxygen,  so  that  the  whole 
heat  of  the  system  must  still  be  referred  to  the  chemical 
changes.  But  if  the  animal  were  engaged  in  turning  a 
piece  of  machinery,  or  in  ascending  a  mountain,  I  appre- 
hend that  in  proportion  to  the  muscular  effort  put  forth 
for  the  purpose,  a  diminution  of  the  heat  evolved  in  the 
system  by  a  given  chemical  action  would  be  experienced." 

*  Phil.  Mag.,  May,  1845.          f  See  the  next  Fragment, 


THE  COPLEY  MEDALIST  OF  1871.  333 

The  italics  in  this  memorable  passage,  written,  it  is  to  be 
remembered,  in  1843,  are  Mr.  Joule's  own. 

The  concluding  paragraph  of  this  British  association 
paper  equally  illustrates  his  insight  and  precision,  regarding 
the  nature  of  chemical  and  latent  heat.  "I  had,"  he 
writes,  "endeavored  to  prove  that  when  two  atoms  com- 
bine together,  the  heat  evolved  is  exactly  that  which  would 
have  been  evolved  by  the  electrical  current  due  to  the 
chemical  action  taking  place,  and  is  therefore  proportional 
to  the  intensity  of  the  chemical  force  causing  the  atoms  to 
combine.  I  now  venture  to  state  more  explicitly,  that  it  is 
not  precisely  the  attraction  of  affinity,  but  rather  the  me- 
chanical force  expended  by  the  atoms  in  falling  toward  one 
another,  which  determines  the  intensity  of  the  current, 
and,  consequently,  the  quantity  of  heat  evolved;  so  that  we 
have  a  simple  hypothesis  by  which  we  may  explain  why 
heat  is  evolved  so  freely  in  the  combination  of  gases,  and 
by  which  indeed  we  may  account  'latent  heat'  as  a  me- 
chanical power,  prepared  for  action,  as  a  watch-spring  is 
when  wound  up.  Suppose,  for  the  sake  of  illustration,  that 
8  Ibs.  of  oxygen  and  1  Ib.  of  hydrogen  were  presented  to 
one  another  in  tjie  gaseous  state,  and  then  exploded;  the 
heat  evolved  would  be  about  1  degree  Fahr.  in  60,000  Ibs. 
of  water,  indicating  a  mechanical  force,  expended  in  the 
combination,  equal  to  a  weight  of  about  50,000,000  Ibs. 
raised  to  the  height  of  one  foot.  Now  if  the  oxygen  and 
hydrogen  could  be  presented  to  each  other  in  a  liquid  state, 
the  heat  of  combination  would  be  less  than  before,  because 
the  atoms  in  combining  would  fall  through  less  space."  No 
words  of  mine  are  needed  to  point  out  the  commanding 
grasp  of  molecular  physics,  in  their  relation  to  the  mechan- 
ical theory  of  heat,  implied  by  this  statement. 

Perfectly  assured  of  the  importance  of  the  principle 
which  his  experiments  aimed  at  establishing,  Mr.  Joule  did 
not  rest  content  with  results  presenting  such  discrepancies 
as  those  above  referred  to.  He  resorted  in  1844  to  entirely 
new  methods,  and  made  elaborate  experiments  on  the 
thermal  changes  produced  in  air  during  its  expansion: 
firstly  against  a  pressure,  and  therefore  performing  work; 
secondly,  against  no  pressure,  and  therefore  performing  no 
work.  He  thus  established  anew  the  relation  between  the 
heat  consumed  and  the  work  done.  From  five  different 
series  of  experiments  he  deduced  five  different  mechanical 


324  FRAGMENTS  OF  SCIENCE. 

equivalents;  the  agreement  between  them  being  far  greater 
than  that  attained  in  his  first  experiments.  The  mean  of 
them  was  802  foot-ponnds.  From  experiments  with 
water  agitated  by  a  paddle-wheel,  he  deduced,  in  1845, 
an  equivalent  of  890  foot-pounds.  In  1847  he  again 
operated  upon  water  and  sperm  oil,  agitated  them  by  a 
paddle-wheel,  determined  their  elevation  of  temperature, 
and  the  mechanical  power  which  produced  it.  From  the 
one  he  derived  an  equivalent  of  781.5  foot-pounds;  from 
the  other  an  equivalent  of  782.1  foot-pounds.  The 
mean  of  these  two  very  close  determinations  is  781.8  foot- 
pounds. 

By  this  time  the  labors  of  the  previous  ten  years  had 
made  Mr.  Joule  completely  master  of  the  conditions  essen- 
tial to  accuracy  and  success.  Bringing  his  ripened  expe- 
rience to  bear  upon  the  subject,  he  executed  in  1849  a 
series  of  40  experiments  on  the  friction  of  water,  50  experi- 
ments on  the  friction  of  mercury,  and  20  experiments 
on  the  friction  of  plates  of  cast  iron.  He  deduced 
from  these  experiments  our  present  mechanical  equivalent 
of  heat,  justly  recognized  all  over  the  world  as  "  Joule's 
equivalent." 

There  are  labors  so  great  and  so  pregnant  in  conse- 
quences, that  they  are  most  highly  praised  when  they  are 
most  simply  stated.  Such  are  the  labors  of  Mr.  Joule. 
They  constitute  the  experimental  foundation  of  a  principle 
of  incalculable  moment,  not  only  to  the  practice,  but  still 
more  to  the  philosophy  of  Science.  Since  the  days  of 
Newton,  nothing  more  important  than  the  theory,  of  which 
Mr.  Joule  is  the  experimental  demonstrator,  has  been 
enunciated. 

I  have  omitted  all  reference  to  the  numerous  minor 
papers  with  which  Mr.  Joule  has  enriched  scientific  litera- 
ture. Nor  have  I  alluded  to  the  important  investigations 
which  he  has  conducted  jointly  with  Sir  William  Thomson. 
But  sufficient,  I  think,  nas  been  here  said  to  show  that,  in 
conferring  upon  Mr.  Joule  the  highest  honor  of  the  Royal 
Society,  the  Council  paid  to  genius  not  only  a  well-won 
tribute,  but  one  which  had  been  fairly  earned  twenty  years 
previously.* 

*  Lord  Beaconsfield  has  recently  honored  himself  and  England  by 
bestowing  an  annual  pension  of  200£.  on  Dr.  Joule. 


THE  COPLEY  MEDALIST  OF  1871.  325 

CHAPTER  XX. 

THE   COPLEY   MEDALIST   OF    1871. 

DR.  JULIUS  ROBERT  MAYER  was  educated  for  the  med- 
ical profession.  In  the  summer  of  1840,  as  he  himself 
informs  us,  he  was  at  Java,  and  there  observed  that  the 
venous  blood  of  some  of  his  patients  had  a  singularly 
bright  red  color.  The  observation  riveted  his  attention; 
he  reasoned  upon  it,  and  came  to  the  conclusion  that  the 
brightness  of  the  color  was  due  to  the  fact  that  a  less 
amount  of  oxidation  sufficed  to  keep  up  the  temperature 
of  the  body  in  a  hot  climate  than  in  a  cold  one.  The 
darkness  of  the  venous  blood  he  regarded  as  the  visible 
sign  of  the  energy  of  the  oxidation. 

It  would  be  trivial  to  remark  that  accidents  such  as  this, 
appealing  to  minds  prepared  for  them,  have  often  led  to 
great  discoveries.  Mayer's  attention  was  thereby  drawn  to 
the  whole  question  of  animal  heat.  Lavoisier  had 
ascribed  this  heat  to  the  oxidation  of  the  food.  "  One 
great  principle,"  says  Mayer,  "  of  the  physiological  theory 
of  combustion,  is  that  under  all  circumstances  the  same 
amount  of  fuel  yields,  by  its  perfect  combustion,  the  same 
amount  of  heat;  that  this  law  holds  good  even  for  vital 
processes;  and  that  hence  the  living  body,  notwithstanding 
all  its  enigmas  and  wonders,  is  incompetent  to  generate 
heat  out  of  nothing." 

But  beyond  the  power  of  generating  internal  heat,  the 
animal  organism  can  also  generate  heat  outside  of  itself. 
A  blacksmith,  for  example,  by  hammering  can  heat  a  nail, 
and  a  savage  by  friction  can  warm  wood  to  its  point  of 
ignition.  Now,  unless  we  give  up  the  physiological  axiom 
that  the  living  body  cannot  create  heat  out  of  nothing, 
"  we  are  driven,"  says  Mayer,  "  to  the  conclusion  that  it  is 
the  total  heat  generated  within  and  without  that  is  to  be 
regarded  as  the  true  calorific  effect  of  the  matter  oxidized 
in  the  body." 

From  this,  again,  he  inferred  that  the  heat  generated  ex- 
ternally must  stand  in  a  fixed  relation  to  the  work  expended 
in  its  production.  For,  supposing  the  organic  processes  to 
remain  the  same;  if  it  were  possible,  by  the  mere  alteration 
of  the  apparatus,  to  generate  different  amounts  of  heat  by 
the  same  amount  of  work,  it  would  follow  that  the 


326  FRAGMENTS  OF  SCIENCE. 

oxidation  of  the  same  amount  of  material  would  sometimes 
yield  a  less,  sometimes  a  greater,  quantity  of  heat. 
"  Hence,"  says  Mayer,  "  that  a  fixed  relation  subsists  be- 
tween heat  and  work,  is  a  postulate  of  the  physiological 
theory  of  combustion." 

This  is  the  simple  and  natural  account,  given  subse- 
quently by  Mayer  himself,  of  the  course  of  thought  started 
by  his  observation  in  Java.  But  the  conviction  once 
formed,  that  an  unalterable  relation  subsists  between  work 
and  heat,  it  was  inevitable  that  Mayer  should  seek  to  ex- 
press it  numerically.  It  was  also  inevitable  that  a  mind 
like  his,  having  raised  itself  to  clearness  on  this  important 
point,  should  push  forward  to  consider  the  relationship  of 
natural  forces  generally.  At  the  beginning  of  1842  his 
work  had  made  considerable  progress;  but  he  had  become 
physician  to  the  town  of  Heilbronn,  and  the  duties  of  his 
profession  limited  the  time  which  he  could  devote  to 
purely  scientific  inquiry.  He  thought  it  wise,  therefore, 
to  secure  himself  against  accident,  and  in  the  spring  of 
1842  wrote  to  Liebig,  asking  him  to  publish  in  his 
"  Annalen  "  a  brief  preliminary  notice  of  the  work  then  ac- 
complished. Liebig  did  so,  and  Dr.  Mayer's  first  paper  is 
contained  in  the  May  number  of  the  "Annalen  "  for  1842. 
Mayer  had  reached  his  conclusions  by  reflecting  on  the 
complex  processes  of  the  living  body;  but  his  first  step  in 
public  was  to  state  definitely  the  physical  principles  on 
which  his  physiological  deductions  were  to  rest.  He  be- 
gins, therefore,  with  the  forces  of  inorganic  nature.  He 
finds  in  the  universe  two  systems  of  causes  which  are  not 
mutually  convertible — the  different  kinds  of  matter  and 
the  different  forms  of  force.  The  first  quality  of  both  he 
affirms  to  be  indestructibility.  A  force  cannot  become 
nothing,  nor  can  it  arise  from  nothing.  Forces  are  con- 
vertible but  not  destructible.  In  the  terminology  of  his 
time,  he  then  gives  clear  expression  to  the  ideas  of  potential 
and  dynamic  energy,  illustrating  his  point  by  a  weight 
resting  upon  the  earth,  suspended  at  a  height  above  the 
earth,  and  actually  falling  to  the  earth.  He  next  fixes  his 
attention  on  cases  where  motion  is  apparently  destroyed, 
without  producing  other  motion;  on  the  shock  of  inelastic 
bodies,  for  example.  Under  what  form  does  the  vanished 
motion  maintain  itself?  Experiment  alone,  says  Mayer, 
can  help  us  here.  He  warms  water  by  stirring  it;  he  refers 


THti  COPLEY  MEDALIST  OP  1871.  327 

to  the  force  expended  in  overcoming  friction.  Motion  in 
both  cases  disappears;  but  heat  is  generated,  and  the  quan- 
tity generated  is  the  equivalent  of  the  motion  destroyed. 
"  Our  locomotives,"  he  observes  with  extraordinary  sagac- 
ity, "maybe  compared  to  distilling  apparatus:  the  heat 
beneath  the  boiler  passes  into  the  motion  of  the  train,  and 
is  again  deposited  as  heat  in  the  axles  and  wheels." 

A  numerical  solution  of  the  relation  between  heat  and 
work  was  what  Mayer  aimed  at,  and  toward  the  end  of  his 
first  paper  he  makes  the  attempt.  It  was  known  that  a 
d'efinite  amount  of  air,  in  rising  one  degree  in  temperature, 
can  take  up  two  different  amounts  of  heat.  If  its  volume 
be  kept  constant,  it  takes  up  one  amount:  if  its  pressure 
be  kept  constant,  it  takes  up  a  different  amount.  These 
two  amounts  are  called  the  specific  heat  under  constant  vol- 
ume and  under  constant  pressure.  The  ratio  of  the  first  to 
the  second  is  as  1:  1.421.  No  man,  to  my  knowledge,  prior 
to  Dr.  Mayer,  penetrated  the  significance  of  these  two  num- 
bers. He  first  saw  that  the  excess  1.421  was  not,  as  then 
universally  supposed,  heat  actually  lodged  in  the  gas,  but 
heat  which  had  been  actually  consumed  by  the  gas  in 
expanding  against  pressure.  The  amount  of  work  here  per- 
formed was  accurately  known,  the  amount  of  heat  consumed 
was  also  accurately  known,  and  from  these  data  Mayer 
determined  the  mechanical  equivalent  of  heat.  Even  in 
this  first  paper  he  is  able  to  direct  attention  to  the  enor- 
mous discrepancy  between  the  theoretic  power  of  the  fuel 
consumed  in  steam-engines,  and  their  useful  effect. 

Though  this  paper  contains  but  the  germ  of  his  further 
labors,  I  think  it  may  be  safely  assumed  that,  as  regards 
the  mechanical  theory  of  heat,  this  obscure  Heilbronn 
physician,  in  the  year  1842,  was  in  advance  of  all  the 
scientific  men  of  the  time. 

Having,  by  the  publication  of  this  paper,  secured  him- 
self against  what  he  calls  "  Eventualitaten,"  he  devoted 
every  hour  of  his  spare  time  to  his  studies,  and  in  1845 
published  a  memoir  which  far  transcends  his  first  one 
in  weight  and  fullness,  and,  indeed,  marks  an  epoch  in 
the  history  of  science.  The  title  of  Mayer's  first  paper 
was,  "  Remarks  on  the  Forces  of  Inorganic  Nature."  The 
title  of  his  second  great  essay  was/'  Organic  Motion  in  its 
Connection  with  Nutrition."  In  it  he  expands  and  illus- 
trates the  physical  principles  laid  down  in  his  first  brief 


328  FRAGMENTS  OF  SCIENCE. 

paper.  He  goes  fully  through  the  calculation  of  the 
mechanical  equivalent  of  heat.  He  calculates  the  perform- 
ances of  steam-engines,  and  finds  that  100  Ibs.  of  coal,  in  a 
good  working  engine,  produce  only  the  same  amount  of 
heat  as  95  Ibs.  in  an  unworking  one;  the  5  missing  Ibs. 
having  been  converted  into  work.  He  determines  the  use- 
ful effect  of  gunpowder,  and  finds  nine  per  cent,  of  the 
force  of  the  consumed  charcoal  invested  on  the  moving 
ball.  He  records  observations  on  the  heat  generated  in 
water  agitated  by  the  pulping-engine  of  a  paper  manufac- 
tory, and  calculates  the  equivalent  of  that  heat  in  horse- 
power. He  compares  chemical  combination  with  mechanical 
combination — the  union  of  atoms  with  the  union  of  falling 
bodies  with  the  earth.  He  calculates  the  velocity  with 
which  a  body  starting  at  an  infinite  distance  would  strike 
the  earth's  surface,  and  finds  that  the  heat  generated  by 
its  collision  would  raise  an  equal  weight  of  water  17,356 
degrees  C.  in  temperature.  He  then  determines  the 
thermal  effect  which  would  be  produced  by  the  earth  itself 
falling  into  the  sun.  So  that  here,  in  1845,  we  have  the 
germ  of  that  meteoric  theory  of  the  sun's  heat  which  Mayer 
developed  with  such  extraordinary  ability  three  years  after- 
ward. He  also  points  to  the  almost  exclusive  efficacy  of 
the  sun's  heat  in  producing  mechanical  motions  upon  the 
earth,  winding  up  with  the  profound  remark,  that  the 
heat  developed  by  friction  in  the  wheels  of  our  wind  and 
water  mills  comes  from  the  sun  in  the  form  of  vibratory 
motion;  while  the  heat  produced  by  mills  driven  by 
tidal  action  is  generated  at  the  expense  "of  the  earth's  axial 
rotation. 

Having  thus,  with  firm  step,  passed  through  the  powers 
of  inorganic  nature,  his  next  object  is  to  bring  his 
principles  to  bear  upon  the  phenomena  of  vegetable  and 
animal  life.  Wood  and  coal  can  burn;  whence  come  their 
heat,  and  the  work  producible  by  that  heat?  From  the 
immeasurable  reservoir  of  the  sun.  Nature  has  proposed 
to  herself  the  task  of  storing  up  the  light  which  streams 
earthward  from  the  sun,  and  of  casting  into  a  permanent 
form  the  most  fugitive  of  all  powers.  To  this  end  she  has 
overspread  the  earth  with  organisms  which,  while  living, 
take  in  the  solar  light,  and  by  its  consumption  generate 
forces  of  another  kind.  These  organisms  are  plants.  The 
vegetable  world,  indeed,  constitutes  the  instrument  where- 


THE  COPLET  MEDALIST  OF  1871.  329 

by  the  wave-motion  of  the  sun  is  changed  into  the  rigid 
form  of  chemical  tension,  and  thus  prepared  for  future 
use.  With  this  prevision,  as  shall  subsequently  be  shown, 
the  existence  of  the  human  race  itself  is  inseparably  con- 
nected. It  is  to  be  observed  that  Mayer's  utterances  are 
far  from  being  anticipated  by  vague  statements  regarding 
the  "  stimulus"  of  light,  or  regarding  coal  as  "  bottled 
sunlight."  He  first  saw  the  full  meaning  of  De  Saussure's 
observation  as  to  the  reducing  power  of  the  solar  rays,  and 
gave  that  observation  its  proper  place  in  the  doctrine  of 
conservation.  In  the  leaves  of  a  tree,  the  carbon  and 
oxygen  of  carbonic  acid,  and  the  hydrogen  and  oxygen  of 
water,  are  forced  asunder  at  the  expense  of  the  sun,  and 
the  amount  of  power  thus  sacrificed  is  accurately  restored 
by  the  combustion  of  the  tree.  The  heat  and  work 
potential  in  our  coal  strata  are  so  much  strength  with- 
drawn from  the  sun  of  former  ages.  Mayer  lays  the  axe  to 
the  root  of  the  notions  regarding  "  vital  force  "which 
were  prevalent  when  he  wrote.  With  the  plain  fact  before 
us  that  in  the  absence  of  the  solar  rays  plants  cannot  per- 
form the  work  of  reduction,  or  generate  chemical  tensions, 
it  is,  he  contends,  incredible  that  these  tensions  should  be 
caused  by  the  mystic  play  of  the  vital  force.  Such  an 
hypothesis  would  cut  off  all  investigation;  it  would  laud  us 
in  a  chaos  of  unbridled  fantasy.  "I  count,"  he  says, 
"  therefore,  upon  your  agreement  with  me  when  I  state,  as 
an  axiomatic  truth,  that  during  vital  processes  the  conver- 
sion only,  and  never  the  creation  of  matter  or  force 
occurs." 

Having  cleared  his  way  through  the  vegetable  world,  as 
he  had  previously  done  through  inorganic  nature,  Mayer 
passes  on  to  the  other  organic  kingdom.  The  physical 
forces  collected  by  plants  become  the  property  of  animals. 
Animals  consume  vegetables,  and  cause  them  to  reunite 
with  the  atmospheric  oxygen.  Animal  heat  is  thus  pro- 
duced; and  not  only  animal  heat,  but  animal  motion. 
There  is  no  indistinctness  about  Mayer  here;  he  grasps  his 
subject  in  all  its  details,  and  reduces  to  figures  the  con- 
comitants of  muscular  action.  A  bowler  who  imparts  to 
an  8-lb.  ball  a  velocity  of  thirty  feet,  consumes  in  the  act 
one-tenth  of  a  grain  of  carbon.  A  man  weighing  150  Ibs., 
who  lifts  his  own  body  to  a  height  of  eight  feet,  consumes 
in  the  act  one  grain  of  carbon.  In  climbing  a  mountain. 


336  FRAGMENTS  OF  SCIENCE. 

10,000  feet  high,  the  consumption  of  the  same  mail  would 
be  2  oz.  4  drs.  50  grs.  of  carbon.  Boussingault  had  deter- 
mined experimentally  the  addition  to  be  made  to  the  food 
of  horses  when  actively  working,  and  Liebig  had  deter- 
mined the  addition  to  be  made  to  the  food  of  men.  Em- 
ploying the  mechanical  equivalent  of  heat,  which  he  had 
previously  calculated,  Mayer  proves  the  additional  food  to 
be  amply  sufficient  to  cover  the  increased  oxidation. 

But  he  does  not  content  himself  with  showing,  in  a 
general  way,  that  the  human  body  burns  according  to 
definite  laws,  when  it  performs  mechanical  work.  He 
seeks  to  determine  the  particular  portion  of  the  body  con- 
sumed, and  in  doing  so  executes  some  noteworthy  calcula- 
tions. The  muscles  of  a  laborer  150  Ibs.  in  weight  weigh 
64  Ibs.;  but  when  perfectly  desiccated  they  fall  to  15  Ibs. 
Were  the  oxidation  corresponding  to  that  laborer's  work 
exerted  on  the  muscles  alone,  they  would  be  utterly  con- 
sumed in  eighty  days.  The  heart  furnishes  a  still  more 
striking  example.  Were  the  oxidation  necessary  to  sus- 
tain the  heart's  action  exerted  upon  its  own  tissue,  it 
would  be  utterly  consumed  in  eight  days.  And  if  we  con- 
fine our  attention  to  the  two  ventricles,  their  action  would 
be  sufficient  to  consume  the  associated  muscular  tissue  in 
3£  days.  Here,  in  his  own  words,  emphasized  in  his  own 
way,  is  Mayer's  pregnant  conclusion  from  these  calcula- 
tions: "  The  muscle  is  only  the  apparatus  by  means  of 
which  the  conversion  of  the  force  is  effected;  but  it  is  not 
the  substance  consumed  in  the  production  of  the  mechanical 
effect."  He  calls  the  blood  "  the  oil  of  the  lamp  of  life;  " 
it  is  the  slow-burning  fluid  whose  chemical  force,  in  the 
furnace  of  the  capillaries,  is  sacrificed  to  produce  animal 
motion.  This  was  Mayer's  conclusion  twenty-six  years 
ago.  It  was  in  complete  opposition  to  the  scientific 
conclusions  of  his  time;  but  eminent  investigators  have 
since  amply  verified  it. 

Thus,  in  baldest  outline,  I  have  sought  to  give  some 
notion  of  the  first  half  of  this  marvelous  essay.  The 
second  half  is  so  exclusively  physiological  that  I  do  not  wish 
to  meddle  with  it.  I  will  only  add  the  illustration  em- 
ployed by  Mayer  to  explain  the  action  of  the  nerves  upon 
the  muscles.  As  an  engineer,  by  the  motion  of  his  finger 
in  opening  a  valve  or  loosing  a  detent,  can  liberate  an 
amount  of  mechanical  motion  almost  infinite  compared 


TBE  COPLEY  MED  A  List  OP  1871.  331 

with  its  excitin-g  cause,  so  the  nerves,  acting  upon  the 
muscles,  can  unlock  an  amount  jof  activity,  wholly  out  of 
proportion  to  the  work  done  by  the  nerves  themselves. 

As  regards  these  questions  of  weightiest  import  to  the 
science  of  physiology,  Dr.  Mayer,  in  1845,  was  assuredly 
far  in  advance  of  all  living  men. 

Mayer  grasped  the  mechanical  theory  of  heat  with  com- 
manding power,  illustrating  it  and  applying  it  in  the  most 
diverse  domains.  He  began,  as  we  have  seen,  with  physical 
principles;  he  determined  the  numerical  relation  between 
heat  and  work;  he  revealed  the  source  of  the  energies  of 
the  vegetable  world,  and  showed  the  relationship  of  the 
heat  of  our  fires  to  the  solar  heat.  He  followed  the  energies 
which  were  potential  in  the  vegetable,  up  to  their  local 
exhaustion  in  the  animal.  But  in  1845  a  new  thought 
was  forced  upon  him  by  his  calculations.  He  then,  for 
the  first  time,  drew  attention  to  the  astounding  amount  of 
heat  generated  by  gravity  where  the  force  has  sufficient 
distance  to  act  through.  He  proved,  as  I  have  before 
stated,  the  heat  of  collision  of  a  body  falling  from  an 
infinite  distance  to  the  earth,  to  be  sufficient  to  raise  the 
temperature  of  a  quantity  of  water,  equal  to  the  falling 
body  in  weight,  17,356  degrees  C.  He  also  found,  in 
1845,  that  the  gravitating  force  between  the  earth  and  sun 
was  competent  to  generate  an  amount  of  heat  equal  to  that 
obtainable  from  the  combustion  of  6,000  times  the  weight 
of  the  earth  of  solid  coal.  With  the  quickness  of  genius 
he  saw  that  we  had  here  a  power  sufficient  to  produce  the 
enormous  temperature  of  the  sun,  and  also  to  account  for 
the  primal  molten  condition  of  our  own  planet.  Mayer 
shows  the  utter  inadequacy  of  chemical  forces,  as  we  know 
them,  to  produce  or  maintain  the  solar  temperature.  He 
shows  that  were  the  sun  a  lump  of  coal  it  would  be  utterly 
consumed  in  5,000  years.  He  shows  the  difficulties  attend- 
ing the  assumption  that  the  sun  is  a  cooling  body;  for, 
supposing  it  to  possess  even  the  high  specific  heat  of  water, 
its  temperature  would  fall  15.000  degrees  in  5,000  years. 
He  finally  concludes  that  the  light  and  heat  of  the  sun 
are  maintained  by  the  constant  impact  of  meteoric  matter. 
I  never  ventured  an  opinion  as  to  the  truth  of  this  theory; 
that  is  a  question  which  may  still  have  to  be  fought  out. 
But  I  refer  to  it  as  an  illustration  of  the  force  of  genius 
with  which  Mayer  followed  the  mechanical  theory  of  heat 


332  FRAGMENTS  OF  SCIENCE. 

through  all  its  applications.  Whether  the  meteoric  theory 
be  a  matter  of  fact  or  not,  with  him  abides  the  honor  of 
proving  to  demonstration  that  the  light  and  heat  of  suns 
•uid  stars  may  be  originated  and  maintained  by  the  colli- 
sions of  cold  planetary  matter. 

It  is  the  man  who  with  the  scantiest  data  could 
accomplish  all  this  in  six  short  years,  and  in  the  hours 
snatched  from  the  duties  of  an  arduous  profession,  that 
the  Royal  Society,  in  1871,  crowned  with  its  highest 
honor. 

Comparing  this  brief  history  with  that  of  the  Copley 
Medalist  of  1870,  the  differentiating  influence  of  "  environ- 
ment," on  two  minds  of  similar  natural  cast  and  endow- 
ment, comes  out  in  an  instructive  manner.  Withdrawn 
from  mechanical  appliances,  Mayer  fell  back  upon  reflec- 
tion, selecting  with  marvelous  sagacity,  from  existing 
physical  data,  the  single  result  on  which  could  be  founded 
a  calculation  of  the  mechanical  equivalent  of  heat.  In  the 
midst  of  mechanical  appliances,  Joule  resorted  to  experi- 
ment, and  laid  the  broad  and  firm  foundation  which  has 
secured  for  the  mechanical  theory  the  acceptance  it  now 
enjoys.  A  great  portion  of  Joule's  time  was  occupied  in 
actual  manipulation;  freed  from  this,  Mayer  had  time  to 
follow  the  theory  into  its  most  abstruse  and  impressive 
applications.  With  their  places  reversed,  however,  Joule 
might  have  become  Mayer,  and  Mayer  might  have  become 
Joule. 

It  does  not  lie  within  the  scope  of  these  brief  articles  to 
enter  upon  the  developments  of  the  Dynamical  Theory 
accomplished  since  Joule  and  Mayer  executed  their 
memorable  labors. 


CHAPTER  XXI. 

DEATH  BY  LIGHTNING. 

PEOPLE  in  general  imagine,  when  they  think  at  all 
about  the  matter,  that  an  impression  upon  the  nerves — a 
blow,  for  example,  or  the  prick  of  a  pin — is  felt  at  the 
moment  it  is  inflicted.  But  this  is  not  the  case.  The 
seat  of  sensation  being  the  brain,  to  it  the  intelligence  of 
any  impression  made  upon  the  nerves  has  to  be  transmitted 


DEA TH  BY  LIGHTNING.  3 33 

before  this  impression  can  become  manifest  as  conscious- 
ness. The  transmission,  moreover,  requires  time,  and  the 
consequence  is,  that  a  wound  inflicted  on  a  portion  of  the 
body  distant  from  the  brain  is  more  tardily  appreciated 
than  one  inflicted  adjacent  to  the  brain.  By  an  extremely 
ingenious  experimental  arrangement,  Helmholtz  has  deter- 
mined the  velocity  of  this  nervous  transmission,  and  finds 
it  to  be  about  eighty  feet  a  second,  or  less  than  oue-thir- 
teen-th  of  the  velocity  of  sound  in  air.  If,  therefore,  a 
whale  forty  feet  long  were  wounded  in  the  tail,  it  would 
not  be  conscious  of  the  injury  till  half  a  second  after  the 
wound  had  been  inflicted.*  But  this  is  not  the  only  in- 
gredient in  the  delay.  There  can  scarcely  be  a  doubt  that 
to  every  act  of  consciousness  belongs  a  determinate  molec- 
ular arrangement  of  the  brain — that  every  thought  or 
feeling  has  its  physical  correlative  in  that  organ;  and 
nothing  can  be  more  certain  than  that  every  physical 
change,  whether  molecular  or  mechanical,  requires  time 
for  its  accomplishment.  So  that,  besides  the  interval  of 
transmission,  a  still  further  time  is  necessary  for  the  brain 
to  put  itself  in  order — for  its  molecules  to  take  up  the 
motions  or  positions  necessary  to  the  completion  of  con- 
sciousness. Helmholtz  considers  that  one-tenth  of  asecond 
is  demanded  for  this  purpose.  Thus,  in  the  case  of  the 
whale  above  supposed,  we  have  first  half  a  second  con- 
sumed in  the  transmission  of  the  intelligence  through  the 
sensor  nerves  to  the  head,  one-tenth  of  asecond  consumed 
by  the  brain  in  completing  the  arrangements  necessary  to 
consciousness,  and,  if  the  velocity  of  transmission  through 
the  motor  be  the  same  as  that  through  the  sensor  nerves, 
half  a  second  in  sending  a  command  to  the  tail  to  defend 
itself.  Thus  one  second  and  a  tenth  would  elapse  before  an 
impression  made  upon  its  caudal  nerves  could  be  responded 
to  by  a  whale  forty  feet  long. 

Now,  it  is  quite  conceivable  that  an  injury  might  be 
inflicted  so  rapidly  that  withint  the  time  required  by  the 
brain  to  complete  the  arrangements  necessary  to  conscious- 
ness, its  power  of  arrangement  might  be  destroyed.  In  such 
a  case,  though  the  injury  might  be  of  a  nature  to  cause 

*  A  most  admirable  lecture  on  the  velocity  of  nervous  transmission 
has  been  published  by  Dr.  Du  Bois-Reyinond  in  the  "  Proceedings  of 
the  Koyal  Institution"  for  1866,  yol,  iv.,  p.  575, 


334  FRAGMENTS  OF  SCIENCE. 

death,  this  would  occur  without  pain.  Death  in  this  case 
would  be  simply  the  sudden  negation  of  life,  without  any 
intervention  of  consciousness  whatever. 

The  time  required  for  a  rifle  bullet  to  pass  clean  through 
a  man's  head  may  be  roughly  estimated  at  a  thousandth  of 
a  second.  Here,  therefore,  we  should  have  no  room  for 
sensation,  and  death  would  be  painless.  But  there  are 
other  actions  which  far  transcend  in  rapidity  that  of  the 
rifle  bullet.  A  flash  of  lightning  cleaves  a  cloud,  appear- 
ing and  disappearing  in  less  than  a  hundred  thousandth  of 
a  second,  and  the  velocity  of  electricity  is  such  as  would 
carry  it  in  a  single  second  over  a  distance  almost  equal  to 
that  which  separates  the  earth  and  moon.  It  is  well  known 
that  a  luminous  impression  once  made  upon  the  retina 
endures  for  about  one-sixth  of  a  second,  and  that  this 
is  the  reason  why  we  see  a  continuous  band  of  light  when 
a  glowing  coal  is  caused  to  pass  rapidly  through  the  air. 
A  body  illuminated  by  an  instantaneous  flash  continues  to 
be  seen  for  the  sixth  of  a  second  after  the  flash  has  become 
extinct;  and  if  the  body  thus  illuminated  be  in  motion,  it 
appears  at  rest  at  the  place  where  the  flash  falls  upon  it. 
When  a  color-top  with  differently  colored  sectors  is  caused 
to  spin  rapidly  the  colors  blend  together.  Such  a  top, 
rotating  in  a  dark  room  and  illuminated  by  an  electric 
spark,  appears  motionless,  each  distinct  color  being  clearly 
seen.  Professor  Dove  has  found  that  a  flash  of  lightning 
produces  the  same  effect.  During  a  thunderstorm  he  put 
a  color-top  in  exceedingly  rapid  motion,  and  found  that 
every  flash  revealed  the  top  as  a  motionless  object  with  its 
colors  distinct.  If  illuminated  solely  by  a  flash  of  lightning, 
the  motion  of  all  bodies  on  the  earth's  surface  would,  as 
Dove  has  remarked,  appear  suspended.  A  cannon  ball, 
for  example,  would  have  its  flight  apparently  arrested, 
and  would  seem  to  hang  motionless  in  space  as  long  as  the 
luminous  impression  which  revealed  the  ball  remained  upon 
the  eye. 

If,  then,  a  rifle  bullet  move  with  sufficient  rapidity  to 
destroy  life  without  the  interposition  of  sensation,  much 
more  is  a  flash  of  lightning  competent  to  produce  this 
effect.  Accordingly,  we  have  well-authenticated  cases  of 
people  being  struck  senseless  by  lightning  who,  on  recov- 
ery, had  no  memory  of  pain.  The  following  circumstan- 
tial case  is  described  by  Hemmer; 


DEATH  BY  L IGHTNING.  335 

On  June  30,  1788,  a  soldier  in  the  neighborhood  of 
Mannheim,  being  overtaken  by  rain,  placed  himself  under 
a  tree,  beneath  which  a  woman  had  previously  taken  shel- 
ter. He  looked  upward  to  see  whether  the  branches  were 
thick  enough  to  afford  the  required  protection,  and,  in 
doing  so,  was  struck  by  lightning,  and  fell  senseless  to  the 
earth.  The  woman  at  his  side  experienced  the  shock  in 
her  foot,  but  was  not  struck  down.  Some  hours  afterward 
the  man  revived,  but  remembered  nothing  about  what  had 
occurred,  save  the  fact  of  his  looking  up  at  the  branches. 
This  was  his  last  act  of  consciousness,  and  he  passed  from 
the  conscious  to  the  unconscious  condition  without  pain. 
The  visible  marks  of  a  lightning  stroke  are  usually  insig- 
nificant: the  hair  is  sometimes  burned;  slight  wounds  are 
observed;  while,  in  some  instances,  a  red  streak  marks  the 
track  of  the  discharge  over  the  skin. 

Under  ordinary  circumstances,  the  discharge  from  a 
small  Leyden  jar  is'exceedingly  unpleasant  to  me.  Some 
time  ago  I  happened  to  stand  in  the  presence  of  a  numerous 
audience,  with  a  battery  of  fifteen  large  Leyden  jars  charged 
beside  me.  Through  some  awkwardness  on  my  part,  I 
touched  a  wire  leading  from  the  battery,  and  the  discharge 
went  through  my  body.  Life  was  absolutely  blotted  out 
for  a  very  sensible  interval,  without  a  trace  of  pain.  In  a 
second  or  so  consciousness  returned;  I  vaguely  discerned 
the  audience  and  apparatus,  and,  by  the  help  of  these  ex- 
ternal appearances,  immediately  concluded  that  I  had  re- 
ceived the  battery  discharge.  The  intellectual  conscious- 
ness of  my  position  was  restored  with  exceeding  rapidity, 
but  not  so  the  optical  consciousness.  To  prevent  the  audi- 
ence from  being  alarmed,  I  observed  that  it  had  often  been 
my  desire  to  receive  accidentally  such  a  shock,  and  that  my 
wish  had  at  length  been  fulfilled.  But,  while  making  this 
remark,  the  appearance  which  my  body  presented  to  my 
eyes  was  that  of  a  number  of  separate  pieces.  The  arms, 
for  example,  were  detached  from  the  trunk,  and  seemed 
suspended  in  the  air.  In  fact,  memory  and  the  power  of 
reasoning  appeared  to  be  complete  long  before  the  optic 
nerve  was  restored  to  healthy  action.  But  what  I  wish 
chiefly  to  dwell  upon  here  is,  the  absolute  painlessness  of 
the  shock;  and  there  cannot,  I  think,  be  a  doubt  that,  to  a 
person  struck  dead  by  lightning,  the  passage  from  life  to 
death  occurs  without  consciousness  being  in  the  least 


336  FRAGMENTS  OF  SCIENCE. 

degree  implicated.     It  is  an  abrupt  stoppage  of  sensation, 
unaccompanied  by  a  pang. 


CHAPTER  XXII. 

SCIENCE   AND  THE    "SPIRITS/* 

THEIR  refusal  to  investigate  "spiritual  phenomena  "  ii 

often  urged  as  a  reproach  against  scientific  men.  I  here 
propose  to  give  a  sketch  of  an  attempt  to  apply  to  the 
"phenomena"  those  methods  of  inquiry  which  are  found 
available  in  dealing  with  natural  truth. 

Some  years  ago,  when  the  spirits  were  particularly  active 
in  this  country,  Faraday  was  invited,  or  rather  entreated, 
by  one  of  his  friends  to  meet  and  question  them.  He  had, 
however,  already  made  their  acquaintance,  and  did  not 
wish  to  renew  it.  I  had  not  been  so*  privileged,  and  he 
therefore  kindly  arranged  a  transfer  of  the  invitation  to 
me.  The  spirits  themselves  named  the  time  of  meeting, 
and  I  was  conducted  to  the  place  at  the  day  and  hour 
appointed. 

Absolute  unbelief  in  the  facts  was  by  no  means  my  con- 
dition of  mind.  On  the  contrary,  I  thought  it  probable 
that  some  physical  principle,  not  evident  to  the  spirit- 
ualists themselves,  might  underlie  their  manifestations. 
Extraordinary  effects  are  produced  by  the  accumulation  of 
small  impulses.  Galileo  set  a  heavy  pendulum  in  motion 
by  the  well-timed  puffs  of  his  breath.  Ellicotsetone  clock 
going  by  the  ticks  of  another,  even  when  the  two  clocks 
were  separated  by  a  wall.  Preconceived  notions  can,  more- 
over, vitiate,  to  an  extraordinary  degree,  the  testimony  of 
even  veracious  persons.  Hence  my  desire  to  witness  those 
extraordinary  phenomena,  the  existence  of  which  seemed 
placed  beyond  a  doubt  by  the  known  veracity  of  those  who 
had  witnessed  and  described  them.  The  meeting  took 
place  at  a  private  residence  in  the  neighborhood  of  London. 
My  host,  his  intelligent  wife,  and  a  gentleman  who  may  be 
called  X.,  were  in  the  house  when  I  arrived.  I  "was 
informed  that  the  "  medium  "  had  not  yet  made  her  appear- 
ance; that  she  was  sensitive,  and  might  resent  suspicion. 
It  was  therefore  requested  that  the  tables  and  chairs  should 
be  examined  before  her  arrival,  in  order  to  be  assured,  that 


SCIENCE  AND  T8ft  "SPIRITS."  33? 

there  was  no  trickery  in  the  furniture.  This  was  done; 
and  I  then  first  learned  that  my  hospitable  host  had 
arranged  that  the  seance  should  be  a  dinner-party.  This 
was  to  me  an  unusual  form  of  investigation;  but  I  accepted 
it,  as  one  of  the  accidents  of  the  occasion. 

The  "  medium  "  arrived — a  delicate-looking  young  lady, 
who  appeared  to  have  suffered  much  from  ill-health.  I 
took  her  to  dinner  and  sat  close  beside  her.  Facts  were 
absent  for  a  considerable  time,  a  series  of  very  wonderful 
narratives  supplying  their  place.  The  duty  of  belief  on 
the  testimony  of  witnesses  was  frequently  insisted  on.  X. 
appeared  to  be  a  chosen  spiritual  agent,  and  told  us  many 
surprising  things.  He  affirmed  that,  when  he  took  a  pen 
in  his  hand,  an  influence  ran  from  his  shoulder  downward, 
and  impelled  him  to  write  oracular  sentences.  I  listened 
for  a  time,  offering  no  observation.  "  And  now,"  con- 
tinued X.,  "  this  power  has  so  risen  as  to  reveal  to  me  the 
thoughts  of  others.  Only  this  morning  I  told  a  friend 
what  he  was  thinking  of,  and  what  he  intended  to  do 
during  the  day."  Here,  I  thought,  is  something  that  can 
be  at  once  tested.  I  said  immediately  to  X.:  "If  you 
wish  to  win  to  your  cause  an  apostle,  who  will  proclaim 
your  principles  to  the  world  from  the  housetop,  tell  me 
what  I  am  now  thinking  of."  X.  reddened,  and  did  not 
tell  me  my  thought. 

Some  time  previously  I  had  visited  Baron  Reichenbach, 
in  Vienna,  and  I  now  asked  the  young  lady  who  sat  beside 
me,  whether  she  could  see  any  of  the  curious  things  which 
he  describes — the  light  emitted  by  crystals,  for  example? 
Here  is  the  conversation  which  followed,  as  extracted  from 
my  notes,  written  on  the  day  following  the  seance. 

Medium. — "Qh,  yes;  but  I  see  light  around  all  bodies." 

/. — "  Even  in  perfect  darkness?" 

Medium. — "  Yes;  I  see  luminous  atmospheres  round  all 
people.  The  atmosphere  which  surrounds  Mr.  R.  C.  would 
fill  this  room  with  light." 

/. — "  You  are  aware  of  the  effects  ascribed  by  Baron 
Reichenbach  to  magnets?" 

Medium. — "Yes;  but  a  magnet  makes  me  terribly  ill." 

/. — "Am  I  to  understand  that,  if  this  room  were  per- 
fectly dark,  you  could  tell  whether  it  contained  a  magnet, 
without  being  informed  of  the  fact?  " 

Medium. — "I  should  know  of  its  presence  on  entering 
the  room." 


338  FRAGMENTS 

/.—"How?" 

Medium. — "  I  should  be  rendered  instantly  ill." 

/. — "  How  do  you  feel  to-day?  " 

Medium. — "  Particularly  well;  I  have  not  been  so  well 
for  mouths." 

/. — "  Then,  may  I  ask  you  whether  there  is,  at  the  pres- 
ent moment,  a  magnet  in  my  possession?" 

The  young  lady  looked  at  me,  blushed,  and  stammered: 

"  No;  I  arn  not  en  rapport  with  you." 

I  sat  at  her  right  hand,  and  a  left-hand  pocket,  within 
six  inches  of  her  person,  contained  a  magnet. 

Our  host  here  deprecated  discussion,  as  it  "exhausted 
the  medium."  The  wonderful  narratives  were  resumed; 
but  I  had  narratives  of  my  own  quite  as  wonderful.  These 
spirits,  indeed,  seemed  clumsy  creations,  compared  with 
those  with  which  my  own  work  had  made  me  familiar.  I 
therefore  began  to  match  the  wonders  related  to  me  by 
other  wonders.  A  lady  present  discoursed  on  spiritual 
atmospheres,  which  she  could  see  as  beautiful  colors  when 
she  closed  her  eyes.  I  professed  myself  able  to  see 
similar  colors,  and,  more  than  that,  to  be  able  to  see  the 
interior  of  my  own  eyes.  The  medium  affirmed  that  she 
could  see  actual  waves  of  light  coming  from  the  sun.  I 
retorted  that  men  of  science  could  tell  the  exact  number 
of  waves  emitted  in  a  second,  and  also  their  exact  length. 
The  medium  spoke  of  the  performances  of  the  spirits  on 
musical  instruments.  I  said  that  snch  performance  was 
gross,  in  comparison  with  a  kind  of  music  which  had  been 
discovered  some  time  previously  by  a  scientific  man.  Stand- 
ing at  a  distance  of  twenty  feet  from  a  jet  of  gas,  he  could 
command  the  flame  to  emit  a  melodious  note;  it  would 
obev,  and  continue  its  song  for  hours.  So  loud  was  the 
music  emitted  by  the  gas-flame,  that  it  might  be  heard  by 
an  assembly  of  a  thousand  people.  These  were  acknowl- 
edged to  be  as  great  marvels  as  any  of  those  of  spiritdom. 
The  spirits  were  then  consulted,  and  I  was  pronounced  to 
be  a  first-class  medium. 

During  this  conversation  a  low  knocking  was  heard  from 
time  to  time  under  the  table.  These,  I  was  told,  were  the 
spirits'  knocks.  I  was  informed  that  one  knock,  in  answer 
to  a  question,  meant  "  No;  "  that  two  knocks  meant  "  Not 
yet;"  and  that  three  knocks  meant  "  Yes."  In  answer  to 
a  question  whether  I  was  a  medium,  the  response  was  three 


SCIENCE  AND  THE  "SPIRITS."  339 

brisk  and  vigorous  knocks.  I  noticed  that  the  knocks 
issued  from  a  particular  locality,  and  therefore  requested 
the  spirits  to  be  good  enough  to  answer  from  another 
corner  of  the  table.  They  did  not  comply;  but  I  was 
assured  that  they  would  do  it,  and  much  more,  by  and  by. 
The  knocks  continuing,  I  turned  a  wine  glass  upside 
down,  and  placed  my  ear  upon  it,  as  upon  a  stethoscope. 
The  spirits  seemed  disconcerted  by  the  act;  they  lost 
their  playfulness,  and  did  not  recover  it  for  a  considerable 
time. 

Somewhat  weary  of  the  proceedings,  I  once  threw  my- 
self back  against  my  chair  and  gazed  listlessly  out  of  the 
window.  While  thus  engaged,  the  table  was  rudely 
pushed.  Attention  was  drawn  to  the  wine,  still  oscillat- 
ing in  the  glasses,  and  I  was  asked  whether  that  was  not 
convincing.  I  readily  granted  the  fact  of  motion,  and  be- 
gan to  feel  the  delicacy  of  my  position.  There  were 
several  pairs  of  arms  upon  the  table,  and  several  pairs  of 
legs  under  it;  but  how  was  I,  without  offense,  to  express 
the  conviction  which  I  really  entertained?  To  ward  off 
the  difficulty,  I  again  turned  a  wine  glass  upside  down  and 
rested  my  ear  upon  it.  The  rim  of  the  glass  was  not  level, 
and  my  hair,  on  touching  it,  caused  it  to  vibrate,  and  pro- 
duce a  peculiar  buzzing  sound.  A  perfectly  candid  and 
warm-hearted  old  gentleman  at  the  opposite  side  of  the 
table,  whom  I  may  call  A.,  drew  attention  to  the  sound, 
and  expressed  his  entire  belief  that  it  was  spiritual.  I, 
however,  informed  him  that  it  was  the  moving  hair  acting 
on  the  glass.  The  explanation  was  not  well  received;  and 
X.,  in  a  tone  of  severe  pleasantry,  demanded  whether  it 
was  the  hair  that  had  moved  the  table.  The  promptness 
of  my  negative  probably  satisfied  him  that  my  notion  was 
a  very  different  one. 

The  superhuman  power  of  the  spirits  was  next  dwelt 
upon.  The  strength  of  man,  it  was  stated,  was  unavailing 
in  opposition  to  theirs.  No  human  power  could  prevent 
the  table  from  moving  when  they  pulled  it.  During  the 
evening  this  pulling  of  the  table  occurred,  or  rather  was 
attempted,  three  times.  Twice  the  table  moved  when  my 
attention  was  withdrawn  from  it;  on  a  third  occasion,  I 
tried  whether  the  act  could  be  provoked  by  an  assumed  air 
of  inattention.  Grasping  the  table  firmly  between  my 
knees,  I  threw  myself  back  in  the  chair,  and  waited,  with 


340  FRAGMENTS  OF  SCIENCE. 

eyes  fixed  on  vacancy,  for  the  pull.  It  came.  For  some 
seconds  it  was  pull  spirit,  hold  muscle;  the  muscle,  however, 
prevailed,  and  the  table  remained  at  rest.  Up  to  the  present 
moment  this  interesting  fact  is  known  only  to  the  partic- 
ular spirit  in  question  and  myself. 

A  species  of  mental  scene-painting,  with  which  my  own 
pursuits  had  long  rendered  rne  familiar,  was  employed  to 
figure  the  changes  and  distribution  of  spiritual  power.  The 
spirits,  it  was  alleged,  were  provided  with  atmospheres, 
which  combined  with  and  interpenetrated  each  other,  and 
considerable  ingenuity  was  shown  in  demonstrating  the 
necessity  of  time  in  effecting  the  adjustment  of  the  atmos- 
pheres. A  rearrangement  of  our  positions  was  proposed  and 
carried  out;  and  soon  afterward  my  attention  was  drawn  to 
a  scarcely  sensible  vibration  on  the  part  of  the  table. 
Several  persons  were  leaning  on  the  table  at  the  time,  and 
I  asked  permission  to  touch  the  medium's  hand.  "Oh! 
I  know  I  tremble,"  was  her  reply.  Throwing  one  leg 
across  the  other,  I  accidentally  nipped  a  muscle,  and  pro- 
duced thereby  an  involuntary  vibration  of  the  free  leg. 
This  vibration,  I  knew,  must  be  communicated  to  the  floor, 
and  thence  to  the  chairs  of  all  present.  I  therefore  inten- 
tionally promoted  it.  My  attention  was  promptly  drawn 
to  the  motion;  and  a  gentleman  besivle  me,  whose  value  as 
a  witness  I  was  particularly  desirous  to  test,  expressed  his 
belief  that  it  was  out  of  the  compass  of  human  power  to 
produce  so  strange  a  tremor.  "  I  believe,"  he  added, 
earnestly,  "  that  it  is  entirely  the  spirits'  work."  "  So  do 
I,"  added,  with  heat,  the  candid  and  warm-hearted  old 
gentleman  A.  "  Why,  sir,"  he  continued,  "I  feel  them 
at  this  moment  shaking  my  chair."  I  stopped  the  motion 
of  the  leg.  "Now,  sir,"  A.  exclaimed,  "they  are  gone." 
I  began  again,  and  A.  once  more  affirmed  their  presence. 
I  could,  however,  notice  that  there  were  doubters  present, 
who  did  not  quite  know  what  to  think  of  the  manifestations. 
I  saw  their  perplexity;  and,  as  there  was  sufficient  reason  to 
believe  that  the  disclosure  of  the  secret  would  simply  pro- 
voke anger,  I  kept  it  to  myself. 

Again  a  period  of  conversation  intervened,  during  which 
the  spirits  became  animated.  The  evening  was  confessedly 
a  dull  one,  but  matters  appeared  to  brighten  toward  its 
close.  The  spirits  were  requested  to  spell  the  name  by 
which  I  was  known  in  the  heavenly  world.  Our  host  com- 


SCIENCE  AND  THE  "  SPIRITS."  341 

tnenced  repeating  the  alphabet,  and  when  he  reached  the 
letter  "  P"  a  knock  was  heard.  He  began  again,  and  the 
spirits  knocked  at  the  letter  "  0."  1  was  puzzled,  but 
waited  for  the  end.  The  next  letter  knocked  down  was 
"  E."  I  laughed,  and  remarked  that  the  spirits  were  going 
to  make  a  poet  of  rne.  Admonished  for  my  levity,  I  was 
informed  that  the  frame  of  mind  proper  for  the  occasion 
ought  to  have  been  superinduced  by  a  perusal  of  the  Bible 
immediately  before  the  seance.  The  spelling,  however, 
went  on,  and  sure  enough  I  came  out  a  poet.  But  matters 
did  not  end  here.  Our  host  continued  his  repetition  of  the 
alphabet,  and  the  next  letter  of  the  name  proved  to  be 
"  0."  Here  was  manifestly  an  unfinished  word,  and  the 
spirits  were  apparently  in  their  most  communicative  mood. 
The  knocks  came  from  under  the  table,  but  no  person 
present  evinced  the  slightest  desire  to  look  under  it.  I 
asked  whether  I  might  go  underneath;  the  permission  was 
granted;  so  I  crept  under  the  table.  Some  tittered;  but  the 
candid  old  A.  exclaimed,  "  He  has  a  right  to  look  into 
the  very  dregs  of  it,  to  convince  himself."  Having  pretty 
well  assured  myself  that  no  sound  could  be  produced  under 
the  table  without  its  origin  being  revealed,  I  requested 
our  host  to  continue  his  questions.  He  did  so,  but  in  vain. 
He  adopted  a  tone  of  tender  en  treaty;  but  the  "dear  spirits" 
had  become  dumb  dogs,  and  refused  to  be  entreated.  I 
continued  under  that  table  for  at  least  a  quarter  of  an  hour, 
after  which,  with  a  feeling  of  despair  as  regards  the  prospects 
of  humanity  never  before  experienced,  I  regained  my  chair. 
Once  there,  the  spirits  resumed  their  loquacity,  and  dubbed 
me  "Poet  of  Science." 

This,  then,  is  the  result  of  an  attempt  made  by  a  scien- 
tific man  to  look  into  these  spiritual  phenomena.  It  is 
not  encouraging;  and  for  this  reason.  The  present  pro- 
moters of  spiritual  phenomena  divide  themselves  into  two 
classes,  one  of  which  needs  no  demonstration,  while  the 
other  is  beyond  the  reach  of  proof.  The  victims  like  to 
believe,  and  they  do  not  like  to  be  undeceived.  Science 
is  perfectly  powerless  in  the  presence  of  this  frame  of  mind. 
It  is,  moreover,  a  state  perfectly  compatible  with  extreme 
intellectual  subtlety  and  a  capacity  for  devising  hypotheses 
which  only  require  the  hardihood  engendered  by  strong 
conviction,  or  by  callous  mendacity,  to  render  them 
impregnable.  The  logical  feebleness  of  science  is  uot  suffi- 


342  FRAGMENTS  OF  SCIENCE. 

ciently  borne  in  mind.  It  keeps  down  the  weed  of  super- 
stition, not  by  logic  but  by  slowly  rendering  the  mental 
soil  unfit  for  its  cultivation.  When  science  appeals  to  uni- 
form experience,  the  spiritualist  will  retort,  "  How  do  you 
know  that  a  uniform  experience  will  continue  uniform? 
You  tell  me  that  the  sun  has  risen  for  six  thousand  years: 
that  is  no  proof  that  it  will  rise  to-morrow;  within  the  next 
twelve  hours  it  may  be  puffed  out  by  the  Almighty." 
Taking  this  ground,  a  man  may  maintain  the  story  of 
"  Jack  and  the  Beanstalk"  in  the  face  of  all  the  science 
in  the  world.  You  urge,  in  vain,  that  science  has  given 
us  all  the  knowledge  of  the  universe  which  we  now  possess, 
while  spiritualism  has  added  nothing  to  that  knowledge. 
The  drugged  soul  is  beyond  the  reach  of  reason.  It  is  in 
vain  that  impostors  are  exposed,  and  the  special  demon 
cast  out.  He  has  but  slightly  to  change  his  shape,  return 
to  his  house,  and  find  it  "empty,  swept,  and  garnished." 


Since  the  time  when  the  foregoing  remarks  were  written 
I  have  been  more  than  once  among  the  spirits,  at  their 
own  invitation.  They  do  not  improve  on  acquaintance. 
Surely  no  baser  delusion  ever  obtained  dominance  over  the 
weak  mind  of  man. 

In  the  bright  sky  they  perceived  an  illuminator;  in  the  all- 
encircling  firmament  an  embracer;  in  the  roar  of  thunder  and  in 
the  violence  of  the  storni  they  felt  the  presence  of  a  shouter  and  of 
furious  strikers;  and  out  of  the  rain  they  created  an  Indra,  or  giver  of 
rain.— MAX  MULLEB. 


CHAPTER  XXIII. 

REFLECTIONS  ON   PRAYER  AND  NATURAL  LAW.     1861. 

AMID  the  apparent  confusion  and  caprice  of  natural 
phenomena,  which  roused  emotions  hostile  to  calm  in- 
vestigation, it  must  for  ages  have  seemed  hopeless  to  seek 
for  law  or  orderly  relation;  and  before  the  thought  of 
law  dawned  upon  the  unfolding  human  mind  these  other- 
wise inexplicable  effects  were  referred  to  personal  agency. 
In  the  fall  of  a  cataract  the  savage  saw  the  leap  of  a  spirit, 
and  the  echoed  thunder-peal  was  to  him  the  hummer-clang 
of  an  exasperated  god.  Propitiation  of  these  terrible  powers. 


REFLECTIONS  ON  PRATER  AND  NATURAL  LAW.  343 

was  the  consequence,  and  sacrifice  was  offered  to  the 
demons  of  earth  and  air. 

But  observation  tends  to  chasten  the  emotions  and  to 
check  those  structural  efforts  of  the  intellect  which  have 
emotion  for  their  base.  One  by  one  natural  phenomena 
came  to  be  associated  with  their  proximate  causes;  the 
idea  of  direct  personal  volition  mixing  itself  with  the 
economy  of  nature  retreating  more  and  more.  Many  of  us 
fear  this  change.  Our  religious  feelings  are  dear  to  us, 
and  we  look  with  suspicion  and  dislike  on  any  philosophy, 
the  apparent  tendency  of  which  is  to  dry  them  up.  Prob- 
ably every  change  from  ancient  savagery  to  our  present 
enlightenment  has  excited,  in  a  greater  or  less  degree,  fears 
of  this  kind.  But  the  fact  is,  that  we  have  not  yet  deter- 
mined whether  its  present  form  is  necessarv  to  the  life  and 
warmth  of  religious  feeling.  We  may  err  in  linking  the 
imperishable  with  the  transitory,  and  confound  the  living 
plant  with  the  decaying  pole  to  which  it  clings.  My 
object,  however,  at  present  is  not  to  argue,  but  to  mark  a 
tendency.  We  have  ceased  to  propitiate  the  powers  of 
nature — ceased  even  to  pray  for  things  in  manifest  contra- 
diction to  natural  laws.  In  Protestant  countries,  at  least, 
I  think  it  is  conceded  that  the  age  of  miracles  is  past. 

At  an  auberge  near  the  foot  of  the  Rhone  glacier,  I  met, 
in  the  summer  of  1858,  an  athletic  young  priest,  who, 
after  a  solid  breakfast,  including  a  bottle  of  wine,  informed 
rne  that  he  had  come  up  to  "  bless  the  mountains."  This 
was  the  annual  custom  of  the  place.  Year  by  year  the 
Highest  was  entreated,  by  official  intercessors,  to  make 
such  meteorological  arrangements  as  should  ensure  food 
and  shelter  for  the  flocks  and  herds  of  the  Valaisians.  A 
diversion  of  the  Rhone,  or  a  deepening  of  the  river's  bed, 
would,  at  the  time  I  now  mention,  have  been  of  incalcu- 
lable benefit  to  the  inhabitants  of  the  valley.  But  the 
priest  would  have  shrunk  from  the  idea  of  asking  the 
Omnipotent  to  open  a  new  channel  for  the  river,  or  to 
cause  a  portion  of  it  to  flow  over  the  Grirnsel  pass,  and 
down  the  valley  of  Oberhasli  to  Brientz.  This  he  would 
have  deemed  a  miracle,  and  he  did  not  come  to  ask  the 
Creator  to  perform  miracles,  but  to  do  something  which  he 
manifestly  thought  lay  quite  within  the  bounds  of  the 
natural  and  nou-miruculous.  A  Protestant  gentleman  who 
was  present  at  the  time  smiled  at  this  recital.  He  had  no 


344  FRAGMENTS  OF  SCIENCE. 

faith  in  the  priest's  blessing;  still,  he  deemed  his  prayer 
different  in  kind  from  a  request  to  open  a  new  river-cut, 
or  to  cause  the  water  to  flow  uphill. 

In  a  similar  manner  the  same  Protestant  gentleman 
would  doubtless  smile  at  the  honest  Tyrolese  priest,  who, 
when  he  feared  the  bursting  of  a  glacier  dam,  offered  the 
sacrifice  of  the  Mass  upon  the  ice  as  a  means*  of  averting 
the  calamity.  That  poor  man  did  not  expect  to  convert 
the  ice  into  adamant,  or  to  strengthen  its  texture,  so  as  to 
enable  it  to  withstand  the  pressure  of  the  water;  nor  did 
he  expect  that  his  sacrifice  would  cause  the  stream  to  roll 
back  upon  its  source  and  relieve  him,  by  a  miracle,  of  its 
presence.  But  beyond  the  boundaries  of  his  knowledge 
lay  a  region  where  rain  was  generated,  he  knew  not  how. 
He  was  not  so  presumptuous  as  to  expect  a  miracle,  but  he 
firmly  believed  that  in  yonder  cloud-land  matters  could  be 
so  arranged,  without  trespass  on  the  miraculous,  that  the 
stream  which  threatened  him  and  his  people  should  be 
caused  to  shrink  within  its  proper  bounds. 

Both  these  priests  fashioned  that  which  they  did  not 
understand  to  their  respective  wants  and  wishes.  In  their 
case  imagination  came  into  play,  uncontrolled  by  a  knowl- 
edge of  law.  A  similar  state  of  mind  was  long  prevalent 
among  mechanicians.  Many  of  these,  among  whom  were 
to  be  reckoned  men  of  consummate  skill,  were  occupied  a 
century  ago  with  the  question  of  perpetual  motion.  They 
aimed  at  constructing  a  machine  which  should  execute 
work  without  the  expenditure  of  power,  and  some  of  them 
went  mad  in  the  pursuit  of  this  object.  The  faith  in  such 
a  consummation,  involving,  as  it  did,  immense  personal 
profit  to  the  inventor,  was  extremely  exciting,  and  every 
attempt  to  destroy  this  faith  was  met  by  bitter  resentment 
on  the  part  of  those  who  held  it.  Gradually,  however,  as 
men  became  more  and  more  acquainted  with  the  true 
functions  of  machinery,  the  dream  dissolved.  The  hope 
of  getting  work  out  of  mere  mechanical  combinations  dis- 
appeared: but  still  there  remained  for  the  speculator  a 
cloud-land  denser  than  that  which  filled  the  imagination 
of  the  Tyrolese  priest,  and  out  of  which  he  still  hoped  to 
evolve  perpetual  motion.  There  was  the  mystic  store  of 
chemic  force,  which  nobody  understood;  there  were  heat 
and  light,  electricity  and  magnetism,  all  competent  to  pro- 
duce mechanical  motion.*  Here,  then,  was  the  mine  in 

*  See  Helmholtz:  "  Wecliselwirkung  der  Naturkrafte." 


REFLECTIONS  ON  PRA  TER  AND  NA  TURAL  LA  W.    345 

which  our  gem  must  be  sought.  A  modified  and  more 
refined  form  of  the  ancient  faith  revived;  and,  for  aught  I 
know,  a  remnant  of  sanguine  designers  may  at  the  present 
moment  be  engaged  on  the  problem  which  like-minded  men 
in  former  ages  left  unsolved. 

And  why  should  a  perpetual  motion,  even  under  modern 
conditions,  be  impossible?  The  answer  to  this  question  is 
the  statement  of  that  great  generalization  of  modern 
science,  which  is  known  under  the  name  of  the  Conser- 
vation of  Energy.  This  principle  asserts  that  no  power 
can  make  its  appearance  in  nature  without  an  equivalent 
expenditure  of  some  other  power;  that  natural  agents  are 
so  related  to  each  other  as  to  be  mutually  convertible,  but 
that  no  new  agency  is  created.  Light  runs  into  heat; 
heat  into  electricity;  electricity  into  magnetism;  magnet- 
ism into  mechanical  force;  and  mechanical  force  again  into 
light  and  heat.  The  Proteus  changes,  but  he  is  ever  the 
same;  and  his  changes  in  nature,  supposing  no  miracle  to 
supervene,  are  the  expression,  not  of  spontaneity,  but  of 
physical  necessity.  A  perpetual  motion,  then,  is  deemed 
impossible,  because  it  demands  the  creation  of  energy, 
whereas  the  principle  of  Conservation  is — no  creation,  but 
infinite  conversion. 

It  is  an  old  remark  that  the  law  which  molds  a  tear 
also  rounds  a  planet.  In  the  application  of  law  in  nature 
the  terms  great  and  small  are  unknown.  Thus  the  prin- 
ciple referred  to  teaches  us  that  the  Italian  wind,  gliding 
over  the  crest  of  the  Matterhorn,  is  as  firmly  ruled  as  the 
earth  in  its  orbital  revolution  round  the  sun;  and  that  the 
fall  of  its  vapor  into  clouds  is  exactly  as  much  a  matter  of 
necessity  as  the  return  of  the  seasons.  The  dispersion, 
therefore,  of  the  slightest  mist  by  the  special  volition  of 
the  Eternal,  would  be  as  much  a  miracle  as  the  rolling  of 
the  Rhone  over  the  Grimsel  precipices,  down  the  valley 
of  Hasli  to  Meyringen  and  Brientz. 

It  seems  to  me  quite  bevond  the  present  power  of  science 
to  demonstrate  that  the  Tyrolese  priest,  or  his  colleague 
of  the  Rhone  valley,  asked  for  an  "  impossibility  "  in  pray- 
ing for  good  weather;  but  Science  can  demonstrate  the 
incompleteness  of  the  knowledge  of  nature  which  limited 
their  prayers  to  this  narrow  ground;  and  she  may  lessen  the 
number  of  instances  in  which  we  "ask  amiss,"  by  showing 
that  we  sometimes  pray  for  the  performance  of  a  miracle 


346  FRAGMENTS  OF  SCIENCE. 

when  we  do  not  intend  it.  She  does  assert,  for  example, 
that  without  a  disturbance  of  natural  law,  quite  as  serious 
as  the  stoppage  of  an  eclipse,  or  the  rolling  of  the  river 
Niagara  up  the  Falls,  no  act  of  humiliation,  individual  or 
national,  could  call  one  shower  from  heaven,  or  deflect 
toward  us  a  single  beam  of  the  sun. 

Those,  therefore,  who  believe  that  the  miraculous  is  still 
active  in  nature,  may,  with  perfect  consistency,  join  in 
our  periodic  prayers  for  fair  weather  and  for  rain:  while 
those  who  hold  that  the  age  of  miracles  is  past,  will,  if 
they  be  consistent,  refuse  to  join  in  these  petitions.  And 
these  latter,  if  they  wish  to  fall  back  upon  such  a  justifi- 
cation, may  fairly  urge  that  the  latest  conclusions  of  science 
are  in  perfect  accordance  with  the  doctrine  of  the  Master 
himself,  which  manifestly  was  that  the  distribution  of 
natural  phenomena  is  not  affected  by  moral  or  religious 
causes.  "  He  maketh  His  sun  to  rise  on  the  evil  and  on 
the  good,  and  sendeth  rain  on  the  just  and  on  the  unjust." 
Granting  "  the  power  of  Free  Will  in  man,"  so  strongly 
claimed  by  Professor  Mansel  in  his  admirable  defense  of 
the  belief  in  miracles,  and  assuming  the  efficacy  of  free 
prayer  to  produce  changes  in  external  nature,  it  necessarily 
follows  that  natural  laws  are  more  or  less  at  the  mercy  of 
man's  volition,  and  no  conclusion  founded  on  the  assumed 
permanence  of  those  laws  would  be  worthy  of  confi- 
dence. 

It  is  a  wholesome  sign  for  England  that  she  numbers 
among  her  clergy  men  wise  enough  to  understand  all  this, 
and  courageous  enough  to  act  up  to  their  knowledge.  Such 
men  do  service  to  public  character,  by  encouraging  a  manly 
and  intelligent  conflict  with  the  real  causes  of  disease  and 
scarcity,  instead  of  a  delusive  reliance  on  supernatural  aid. 
But  they  have  also  a  value  beyond  this  local  and  temporary 
one.  They  prepare  the  public  mind  for  changes,  which 
though  inevitable,  could  hardly,  without  such  preparation, 
be  wrought  without  violence.  Iron  is  strong;  still,  water 
in  crystallizing  will  shiver  an  iron  envelope,  and  the  more 
unyielding  the  metal  is,  the  worse  for  its  safety.  There 
are  in  the  world  men  who  would  encompass  philosophic 
speculation  by  a  rigid  envelope,  hoping  thereby  to  restrain 
it,  but  in  reality  giving  it  explosive  force.  In  England, 
thanks  to  men  of  the  stamp  to  which  I  have  alluded,  scope 
is  gradually  given  to  thought  for  changes  of  aggregation, 


REFLECTIONS  ON  PRA  TER  AND  NA  TURAL  LA  W.    34? 

and  the  envelope  slowly  alters  its  form,  iu  accordance  with 
the  necessities  of  the  time. 

The  proximate  origin  of  the  foregoing  slight  article,  and  probably 
the  remoter  origin  of  the  next  following  one,  was  this.  Some  years 
ago,  a  day  of  prayer  and  humiliation,  on  account  of  a  bad  harvest, 
was  appointed  by  the  proper  religious  authorities;  but  certain  clergy- 
men of  the  Church  of  England,  doubting  the  wisdom  of  the  demon- 
stration, declined  to  join  in  the  services  of  the  day.  For  this  act  of 
nonconformity  they  were  severely  censured  by  some  of  their  brethren. 
Rightly  or  wrongly,  my  sympathies  were  on  the  side  of  these  men; 
and,  to  lend  them  a  helping  hand  in  their  struggle  against  odds,  I 
inserted  the  foregoing  chapter  in  a  little  book  entitled  "  Mountain- 
eering in  1861."  Some  time  subsequently  I  received  from  a  gentle- 
man of  great  weight  and  distinction  in  the  scientific  world,  and,  I 
believe,  of  perfect  orthodoxy  in  the  religious  one,  a  note  directing  my 
attention  to  an  exceedingly  thoughtful  article  on  Prayer  and  Cholera 
in  the  Pall  Mall  Gazette.  My  eminent  correspondent  deemed  the 
article  a  fair  answer  to  the  remarks  made  by  me  in  1861.  I,  also, 
was  struck  by  the  temper  and  ability  of  the  article,  but  I  could  not 
deem  its  arguments  satisfactory,  and  in  a  short  note  to  the  editor 
of  the  Pall  Mall  Gazette  I  ventured  to  state  so  much.  This  letter 
elicited  some  very  able  replies,  and  a  second  leading  article  was  also 
devoted  to  the  subject.  In  answer  to  all  I  risked  the  publication  of 
a  second  letter,  and  soon  afterward,  by  an  extremely  courteous  note 
from  the  editor,  the  discussion  was  closed. 

Though  thus  stopped  locally,  the  discussion  flowed  in  other  direc- 
tions. Sermons  were  preached,  essays  were  published,  articles  were 
written,  while  a  copious  correspondence  occupied  the  pages  of  some 
of  the  religious  newspapers.  It  gave  me  sincere  pleasure  to  notice 
that  the  discussion,  save  in  a  few  cases  where  natural  coarseness  had 
the  upper  hand,  was  conducted  with  a  minimum  of  vituperation. 
The  severity  shown  was  hardly  more  than  sufficient  to  demonstrate 
earnestness,  while  gentlemanly  feeling  was  too  predominant  to 
permit  that  earnestness  to  contract  itself  to  bigotry  or  to  clothe 
itself  in  abuse.  It  was  probably  the  memory  of  this  discussion  which 
caused  another  excellent  friend  of  mine  to  recommend  to  my  perusal 
the  exceedingly  able  work  which  in  the  next  article  I  have  endeav- 
ored to  review. 


848  FRAGMENTS  OF  SCIENCE. 

CHAPTER  XXIV. 

MIRACLES  AND  SPECIAL  PROVIDENCES.*  1867. 

Mr.  Mozley's  book  belongs  to  that  class  of  writing  of  which  Butler 
may  be  taken  as  the  type.  It  is  strong,  genuine  argument  about 
difficult  matters,  fairly  tracing  what  is  difficult,  fairly  trying  to 
grapple,  not  with  what  appears  the  gist  and  strong  point  of  a  ques- 
tion, but  with  what  really  at  bottom  is  the  knot  of  it.  It  is  a  book 
the  reasoning  of  which  may  not  satisfy  every  one.  .  .  .  But  we  think 
it  is  a  book  for  people  who  wish  to  see  a  great  subject  handled  on  a 
scale  which  befits  it,  and  with  a  perception  of  its  real  elements.  It  is 
a  book  which  will  have  attractions  for  those  who  like  to  see  a  power- 
ful mind  applying  itself,  without  shrinking  or  holding  back,  without 
trick  or  reserve  or  show  of  any  kind,  as  a  wrestler  closes  body  to 
body  with  his  antagonist,  to  the  strength  of  an  adverse  and  powerful 
argument.— TIMES,  Tuesday,  June  5,  1866. 

We  should  add,  that  the  faults  of  the  work  are  wholly  on  the  sur- 
face and  in  the  arrangement;  that  the  matter  is  as  solid  and  as  logical 
as  that  of  any  book  within  recent  memory,  and  that  it  abounds  in 
striking  passages,  of  which  we  have  scarcely  been  able  even  to  give  a 
sample.  No  future  arguer  against  miracles  can  afford  to  pass  it  over. 
—SATURDAY  REVIEW,  September  15,  1866. 

IT  is  my  privilege  to  enjoy  the  friendship  of  a  select 
number  of  religious  men,  with  whom  I  converse  frankly 
upon  theological  subjects,  expressing  without  disguise 
the  notions  and  opinions  I  entertain  regarding  their 
tenets,  and  hearing  in  return  these  notions  and  opinions 
subjected  to  criticism.  I  have  thus  far  found  them  liberal 
and  loving  men,  patient  in  hearing,  tolerant  in  reply, 
who  know  how  to  reconcile  the  duties  of  courtesy  with  the 
earnestness  of  debate.  From  one  of  these,  nearly  a  year 
ago,  I  received  a  note,  recommending  strongly  to  my 
attention  the  volume  of  "  Bampton  Lectures  "  for  1865,  in 
which  the  question  of  miracles  is  treated  by  Mr.  Mozley. 
Previous  to  receiving  this  note,  I  had  in  part  made  the 
acquaintance  of  the  work  through  an  able  and  elaborate 
review  of  it  in  the  Times.  The  combined  effect  of  the 
letter  and  the  review  was  to  make  the  book  the  companion 
of  my  summer  tour  in  the  Alps.  There,  during  the  wet 
and  snowy  days  which  were  only  too  prevalent  in  1866,  and 
during  the  days  of  rest  interpolated  between  days  of  toil.  I 
made  myself  more  thoroughly  conversant  with  Mr. 

*  Fortnightly  Review,  New  Series,  vol.  i.,  p.  645. 


MIRACLES  AND  SPECIAL  PROVIDENCES.     349 

Mozley's  volume.  I  found  it  clear  and  strong — an  intellec- 
tual tonic,  as  bracing  and  pleasant  to  my  mind  as  the  keen 
air  of  the  mountains  was  to  my  body.  From  time  to  time 
I  jotted  down  thoughts  regarding  it,  intending  afterward 
to  work  them  up  into  a  coherent  whole.  Other  duties,  how- 
ever, interfered  with  the  complete  carrying  out  of  this 
intention,  and  what  I  wrote  last  summer  I  now  publish, 
not  hoping  to  be  able,  within  any  reasonable  time,  to 
render  my  defense  of  scientific  method  more  complete. 

Mr.  Mozlev  refers  at  the  outset  of  his  task  to  the  move- 
ment against  miracles  which  of  late  years  has  taken  place, 
and  which  determined  his  choice  of  a  subject.  He  acquits 
modern  science  of  having  had  any  great  share  in  the  pro- 
duction of  this  movement.  The  objection  against  miracles, 
he  says,  does  not  arise  from  any  minute  knowledge  of  the 
laws  of  nature,  but  simply  because  they  are  opposed  to  that 
plain  and  obvious  order  of  nature  which  everybody  sees. 
The  present  movement  is,  he  thinks,  to  be  ascribed  to  the 
greater  earnestness  and  penetration  of  the  present  age. 
Formerly  miracles  were  accepted  without  question,  because 
without  reflection;  but  the  exercise  of  the  "  historic  imag- 
ination" is  a  characteristic  of  our  own  time.  Men  are  now 
accustomed  to  place  before  themselves  vivid  images  of 
historic  facts;  and  when  a  miracle  rises  to  view,  they  halt 
before  the  astounding  occurrence,  and,  realizing  it  with 
the  same  clearness  as  if  it  were  now  passing  before  their 
eyes,  they  ask  themselves,  "  Can  this  have  taken  place?" 
In  some  instances  the  effort  to  answer  this  question  has  led 
to  a  disbelief  in  miracles,  in  others  to  a  strengthening  of 
belief.  The  aim  of  Mr.  Mozley's  lectures  is  to  show  that 
the  strengthening  of  belief  is  the  logical  result  which  ought 
to  follow  from  the  examination  of  the  facts. 

Attempts  have  been  made  by  religious  men  to  bring  the 
Scripture  miracles  within  the  scope  of  the  order  of  nature, 
but  all  such  attempts  are  rejected  by  Mr.  Mozley  as  utterly 
futile  and  wide  of  the  mark.  Regarding  miracles  as  a 
necessary  accompaniment  of  a  revelation,  their  evidential 
value  in  his  eyes  depends  entirely  upon  their  deviation 
from  the  order  of  nature.  Thus  deviating,  they  suggest 
and  illustrate  a  power  higher  than  nature,  a  "  personal 
will;"  and  they  commend  the  person  in  whom  this  power 
is  vested  as  a  messenger  from  on  high.  Without  these 
credentials  such  a  messenger  would  have  no  right  to  demand 


350  FRAGMENTS  OF  SCIENCE. 

belief,  even  were  his  assertions  regarding  his  divine  mis- 
sion backed  by  a  holy  life.  Nor  is  it  by  miracles  alone 
that  the  order  of  nature  is,  or  may  be,  disturbed.  The 
material  universe  is  also  the  arena  of  "  special  providences." 
Under  these  two  heads  Mr.  Mozley  distributes  the  total 
preternatural.  One  form  of  the  preternatural  may  shade 
into  the  other,  as  one  color  passes  into  another  in  the  rain- 
bow; but,  while  the  line  which  divides  the  specially  provi- 
dential from  the  miraculous  cannot  be  sharply  drawn, 
their  distinction  broadly  expressed  is  this:  that  while  a 
special  providence  can  only  excite  surmise  more  or  less 
probable,  it  is  "  the  nature  of  a  miracle  to  give  proof,  as 
distinguished  from  mere  surmise,  of  Divine  design." 

Mr.  Mozley  adduces  various  illustrations  of  what  he  re- 
gards to  be  special  providences,  as  distinguished  from  mir- 
acles. "  The  death  of  Arius,"  he  says,  "was  not  miraculous, 
because  the  coincidence  of  the  death  of  a  heresiarch  taking 
place  when  it  was  peculiarly  advantageous  to  the  orthodox 
faith  ....  was  not  such  as  to  compel  the  inference  of  ex- 
traordinary Divine  agency;  but  it  was  a  special  providence, 
because  it  carried  a  reasonable  appearance  of  it.  The 
miracle  of  the  Thundering  Legion  was  a  special  providence, 
but  not  a  miracle,  for  the  same  reason,  because  the  coin- 
cidence of  an  instantaneous  fall  of  rain,  in  answer  to 
prayer,  carried  some  appearance,  but  not  proof,  of  preter- 
natural agency."  The  eminent  lecturer's  remarks  on  this 
head  brought  to  my  recollection  certain  narratives  pub- 
lished in  Methodist  magazines,  which  I  used  to  read  with 
avidity  when  a  boy.  The  general  title  of  these  exciting 
stories,  if  I  remember  right,  was  "  The  Providence  of  God 
asserted,"  and  in  them  the  most  extraordinary  escapes  from 
peril  were  recounted  and  ascribed  to  prayer,  while  equally 
wonderful  instances  of  calamity  were  adduced  as  illus- 
trations of  Divine  retribution.  In  such  magazines,  or 
elsewhere,  I  found  recorded  the  case  of  the  celebrated 
Samuel  Hick,  which,  as  it  illustrates  a  whole  class  of  spe- 
cial providences  approaching  in  conclusiveness  to  miracles, 
is  worthy  of  mention  here.  It  is  related  of  this  holy  man 
that,  on  one  occasion,  flour  was  lacking  to  make  the  sacra- 
mental bread.  Grain  was  present,  and  a  windmill  was 
E resent,  but  there  was  no  wind  to  grind  the  corn.  With 
lith  undoubting,  Samuel  Hick  prayed  to  the  Lord  of  the 
winds;  the  sails  turned,  the  corn  was  ground,  after  which 


MIRACLES  AND  SPECIAL  PROVIDENCES.        351 

the  wind  ceased.  According  to  the  canon  of  the  Bampton 
lecturer,  this,  though  carrying  a  strong  appearance  of  an 
immediate  exertion  of  Divine  energy,  lacks  by  a  hair's 
breadth  the  quality  of  a  miracle.  For  the  wind  might  have 
arisen,  and  might  have  ceased,  in  the  ordinary  course  of 
nature.  Hence  the  occurrence  did  not  "compel  the  in- 
ference of  extraordinary  Divine  agency."  In  like  manner 
Mr.  Mozley  considers  that  "  the  appearance  of  the  cross  to 
Constantino  was  a  miracle,  or  a  special  providence,  accord- 
ing to  what  account  of  it  we  adopt.  As  only  a  meteoric 
appearance  in  the  shape  of  a  cross  it  gave  some  token  of 
preternatural  agency,  but  not  full  evidence." 

In  the  Catholic  canton  of  Switzerland  where  I  now 
write,  and  still  more  among  the  pious  Tyrolese,  the  moun- 
tains are  dotted  with  shrines,  containing  offerings  of  all 
kinds,  in  acknowledgment  of  special  mercies — legs,  feet, 
arms,  and  hands — of  gold,  silver,  brass,  and  wood,  accord- 
ing as  worldly  possessions  enabled  the  grateful  heart  to 
express  its  indebtedness.  Most  of  these  offerings  are  made 
to  the  Virgin  Mary.  They  are  recognitions  of  "  special 
providences,"  wrought  through  the  instrumentality  of  the 
Mother  of  God.  Mr.  Mozley's  belief,  that  of  the  Methodist 
chronicler,  and  that  of  the  Tyrolese  peasant,  are  substan- 
tially the  same.  Each  of  them  assumes  that  nature  instead 
of  flowing  ever  onward  in  the  uninterrupted  rhythm  of 
cause  and  effect,  is  mediately  ruled  by  the  free  human  will. 
As  regards  direct  action  upon  natural  phenomena,  man's 
wish  and  will,  as  expressed  in  prayer,  are  confessedly  power- 
less; but  prayer  is  the  trigger  which  liberates  the  divine 
power,  and  to  this  extent,  if  the  will  be  free,  man,  of  course, 
commands  nature. 

Did  the  existence  of  this  belief  depend  solely  upon  the 
material  benefits  derived  from  it,  it  could  not,  in  my  opinion, 
last  a  decade.  As  a  purely  objective  fact,  we  should  soon 
see  that  the  distribution  of  natural  phenomena  is  unaffected 
by  the  merits  or  the  demerits  of  men;  that  the  law  of 

fravitation  crushes  the  simple  worshipers  of  Ottery  St. 
lary,  while  singing  their  hymns,  just  as  surely  as  if  they 
were  engaged  in  a  midnight  brawl.  The  hold  of  this  be- 
lief upon  the  human  mind  is  not  due  to  outward  verification, 
but  to  the  inner  warmth,  force,  and  elevation  with  which 
it  is  commonly  associated.  It  is  plain,  however,  that  these 
feelings  may  exist  under  the  most  various  forms.  They 


352  FRAGMENTS  OF  SCIENCE. 

are  not  limited  to  Church  of  England  Protestantism — they 
are  not  even  limited  to  Christianity.  Though  less  refined, 
they  are  certainly  not  less  strong  in  the  heart  of  the  Meth- 
odist and  the  Tyrolese  peasant  than  in  the  heart  of  Mr. 
Mozley.  Indeed,  those  feelings  belong  to  the  primal 
powers  of  man's  nature.  A  "  skeptic"  may  have  them. 
They  find  vent  in  the  battle-cry  of  the  Moslem.  They 
take  hue  and  form  in  the  hunting-grounds  of  the  Red 
Indian;  and  raise  all  of  them,  as  they  raise  the  Christian, 
upon  a  wave  of  victory,  above  the  terrors  of  the  grave. 

The  character,  then,  of  a  miracle,  as  distinguished  from 
a  special  providence,  is  that  the  former  furnishes  proof, 
while  in  the  case  of  the  latter  we  have  only  surmise.  Dis- 
solve the  element  of  doubt,  and  the  alleged  fact  passes 
from  the  one  class  of  the  preternatural  into  the  other.  In 
other  words,  if  a  special  providence  could  be  proved  to  be 
a  special  providence,  it  would  cease  to  be  a  special  provi- 
dence and  become  a  miracle.  There  is  not  the  least 
cloudiness  about  Mr.  Mozley's  meaning  here.  A  special 
providence  is  a  doubtful  miracle.  Why,  then,  not  call  it 
so?  The  term  employed  by  Mr.  Mozley  conveys  no 
negative  suggestion,  whereas  the  negation  of  certainty  is 
the  peculiar  characteristic  of  the  thing  intended  to  be  ex- 
pressed. There  is  an  apparent  unwillingness  on  the  part 
of  the  lecturer  to  call  a  special  providence  what  his  own 
definition  makes  it  to  be.  Instead  of  speaking  of  it  as  a 
doubtful  miracle,  he  calls  it  "an  invisible  miracle."  He 
speaks  of  the  point  of  contact  of  supernatural  power  with 
the  chain  of  causation  being  so  high  up  as  to  be  wholly,  or 
in  part,  out  of  sight,  whereas  the  essence  of  a  special  provi- 
dence is  the  uncertainty  whether  there  is  any  contact  at  all, 
either  high  or  low.  By  the  use  of  an  incorrect  term,  how- 
ever, a  grave  danger  is  avoided.  For  the  idea  of  doubt,  if 
kept  systematically  before  the  mind,  would  soon  be  fatal  to 
the  special  providence,  considered  as  a  means  of  edifica- 
tion. The  term  employed,  on  the  contrary,  invites  and 
encourages  the  trust  which  is  necessary  to  supplement  the 
evidence. 

This  inner  trust,  though  at  first  rejected  by  Mr.  Mdzley 
in  favor  of  external  proof,  is  subsequently  called  upon  to 
do  momentous  duty  in  regard  to  miracles.  Whenever  the 
evidence  of  the  miraculous  seems  incommensurate  with  the 
fact  which  it  has  to  establish,  or  rather  when  the  fact  is  so 


MIRACLES  AND  SPECIAL  PROVIDENCES.        353 

amazing  that  hardly  any  evidence  is  sufficient  to  establish 
it,  Mr.  Mozley  invokes  "  the  affections."  They  must  urge 
the  reason  to  accept  the  conclusion,  from  which  unaided  it 
recoils.  The  affections  and  emotions  are  eminently  the 
court  of  appeal  in  matters  of  real  religion,  which  is  an 
affair  of  the  heart;  but  they  are  not,  I  submit,  the  court  in 
which  to  weigh  allegations  regarding  the  credibility  of  phys- 
ical facts.  These  must  be  judged  by  the  dry  light  of  the 
intellect  alone,  appeals  to  the  affections  being  reserved  for 
cases  where  moral  elevation,  and  not  historic  conviction,  is 
the  aim.  It  is,  moreover,  because  the  result,  in  the  case 
under  consideration,  is  deemed  desirable  that  the  affections 
are  called  upon  to  back  it.  If  undesirable,  they  would,  with 
equal  right,  be  called  upon  to  act  the  other  way.  Even  to 
the  disciplined  scientific  mind  this  would  be  a  dangerous 
doctrine.  A  favorite  theory — the  desire  to  establish  or 
avoid  a  certain  result — can  so  warp  the  mind  as  to  destroy 
its  powers  of  estimating  facts.  I  have  known  men  to  work 
for  years  under  a  fascination  of  this  kind,  unable  to  ex- 
tricate themselves  from  its  fatal  influence.  They  had 
certain  data,  but  not,  as  it  happened,  enough.  By  a  proc- 
ess exactly  analogous  to  that  invoked  by  Mr.  Mozley,  they 
supplemented  the  data,  and  went  wrong.  From  that  hour 
their  intellects  were  so  blinded  to  the  perception  of  adverse 
phenomena  that  they  never  readied  truth.  If,  then,  to 
the  disciplined  scientific  mind,  this  incongruous  mixture 
of  proof  and  trust  be  fraught  with  danger,  what  must  it  be 
to  the  indiscriminate  audience  which  Mr.  Mozley  addresses? 
In  calling  upon  this  agency  he  acts  the  part  of  Franken- 
stein. It  is  a  monster  thus  evoked  that  we  see  stalking 
abroad,  in  the  degrading  spiritualistic  phenomena  of  the 
present  day.  Again,  I  say,  where  the  aim  is  to  elevate  the 
mind,  to  quicken  the  moral  sense,  to  kindle  the  fire  of 
religion  in  the  soul,  let  the  affections  by  all  means  be 
invoked;  but  they  must  not  be  permitted  to  color  our 
reports,  or  to  influence  our  acceptance  of  reports  of  occur- 
rences in  external  nature.  Testimony  as  to  natural  facts 
is  worthless  when  wrapped  in  this  atmosphere  of  the 
affections;  the  most  earnest  subjective  truth  being  thus 
rendered  perfectly  compatible  with  the  most  astounding 
objective  error. 

There  are  questions  in  judging  of  which  the  affections 
or  sympathies  are  often  our  best  guides,  the  estimation  of 


354  FRAGMENTS  OF  SCIENCE. 

moral  goodness  being  one  of  these.  But  at  this  precise 
point,  where  they  are  really  of  use,  Mr.  Mozley  excludes 
the  affections  and  demands  a  miracle  as  a  certificate  of 
character.  He  will  not  accept  any  other  evidence  of  the 
perfect  goodness  of  Christ.  "  No  outward  life  and 
conduct,"  he  says,  "  however  irreproachable,  could  prove 
His  perfect  sinlessness,  because  goodness  depends  upon  the 
inward  motive,  and  the  perfection  of  the  inward  motive  is 
not  proved  by  the  outward  act."  But  surely  the  miracle 
is  an  outward  act,  and  to  pass  from  it  to  the  inner  motive 
imposes  a  greater  strain  upon  logic  than  that  involved  in 
our  ordinary  methods  of  estimating  men.  There  is,  at 
least,  moral  congruity  between  the  outward  goodness  and 
the  inner  life,  but  there  is  no  such  cougruity  between  the 
miracle  and  the  life  within.  The  test  of  moral  goodness 
laid  down  by  Mr.  Mozley  is  not  the  test  of  John,  who  says, 
"  He  that  doeth  righteousness  is  righteous;"  nor  is  it  the 
test  of  Jesus:  "  By  their  fruits  ye  shall  know  them:  do  men 
gather  grapes  of  thorns,  or  figs  of  thistles?"  But  it  is  the 
test  of  another:  "  If  thou  be  the  Son  of  God,  command 
that  these  stones  be  made  bread."  For  my  own  part,  I 
prefer  the  attitude  of  Fichte  to  that  of  Mr.  Mozley.  "  The 
Jesus  of  John,"  says  this  noble  and  mighty  thinker, 
"  knows  no  other  God  than  the  True  God,  in  whom  we  all 
are,  and  live,  and  may  be  blessed,  and  out  of  whom  there 
is  only  Death  and  Nothingness.  And,"  continues  Fichte, 
"he  appeals,  and  rightly  appeals,  in  support  of  this  truth, 
not  to  reasoning,  but  to  the  inward  practical  sense  of  truth 
in  man,  not  even  knowing  any  other  proof  than  this  inward 
testimony,  '  If  any  man  will  do  the  will  of  Him  who  sent 
Me,  he  shall  know  of  the  doctrine  whether  it  be  of  God/  " 
Accepting  Mr.  Mozley's  test,  with  which  alone  I  am 
now  dealing,  it  is  evident  that,  in  the  demonstration  of 
moral  goodness,  the  quantity  of  the  miraculous  comes  into 
play.  Had  Christ,  for  example,  limited  himself  to  the 
conversion  of  water  into  wine,  He  would  have  fallen  short 
of  the  performance  of  Jannes  and  Jambres;  for  it  is  a 
smaller  thing  to  convert  one  liquid  into  another  than  to 
convert  a  dead  rod  into  a  living  serpent.  But  Jannes  and 
Jambres,  we  are  informed,  were  not  good.  Hence,  if  Mr. 
Mozley's  test  be  a  true  one,  a  point  must  exist,  on  the  one 
side  of  which  miraculous  power  demonstrates  goodness, 
while  on  the  other  side  it  does  not.  How  is  this  "point 


MIRACLES  AND  SPECIAL  PROVIDENCES.        355 

of  contrary  flexure"  to  be  determined?  It  must  lie  some- 
where between  the  magicians  and  Moses,  for  within  this 
space  the  power  passed  from  the  diabolical  to  the  Divine. 
But  how  to  mark  the  point  of  passage — how,  out  of  a  purely 
quantitative  difference  in  the  visible  manifestation  of  power, 
we  are  to  infer  a  total  inversion  of  quality — it  is  extremely- 
difficult  to  see.  Moses,  we  are  informed,  produced  a  large 
reptile;  Jannes  and  Jambres  produced  a  small  one.  I  do 
not  possess  the  intellectual  faculty  which  would  enable  me 
to  infer,  from  those  data,  either  the  -goodness  of  the  one  or 
the  badness  of  the  other;  and  in  the  highest  recorded  man- 
ifestations of  the  miraculous  I  am  equally  at  a  loss.  Let 
us  not  play  fast  and  loose  with  the  miraculous;  either  it  is 
a  demonstration  of  goodness  in  all  cases  or  in  none.  If 
Mr.  Mozley  accepts  Christ's  goodness  as  transcendent,  be- 
cause He  did  such  works  as  no  other  man  did,  he  ought, 
logically  speaking,  to  accept  the  works  of  those  who,  in 
His  name,  had  cast  out  devils,  as  demonstrating  a  propor- 
tionate goodness  on  their  part.  But  it  is  people  of  this 
class  who  are  consigned  to  everlasting  fire  prepared  for  the 
devil  and  his  angels.  Such  zeal  as  that  of  Mr.  Mozley  for 
miracles  tends,  I  fear,  to  eat  his  religion  up.  The  logical 
threatens  to  stifle  the  spiritual.  The  truly  religious  soul 
needs  no  miraculous  proof  of  the  goodness  of  Christ.  The 
words  addressed  to  Matthew  at  the  receipt  of  custom  re- 
quired no  miracle  to  produce  obedience.  It  was  by  no 
stroke  of  the  supernatural  that  Jesus  caused  those  sent  to 
seize  Him  to  go  backward  and  fall  to  the  ground.  It  was 
the  sublime  and  holy  effluence  from  within,  which  needed 
no  prodigy  to  commend  it  to  the  reverence  even  of  his 
foes. 

As  regards  the  function  of  miracles  in  the  founding  of  a 
religion,  Mr.  Mozley  institutes  a  comparison  between  the  re- 
ligion of  Christ  and  that  of  Mohammed;  and  he  derides  the 
latter  as  "  irrational  "  because  it  does  not  profess  to  adduce 
miracles  in  proof  of  its  supernatural  origin.  But  the  religion 
of  Mohammed,  notwithstanding  this  drawback,  has  thriven 
in  the  world,  and  at  one  time  it  held  sway  over  larger 

Sopulations  than  Christianity  itself.     The  spread  and  in- 
uence  of  Christianity  are,  however,  brought  forward  by 
Mr.  Mozley  as  '•'  a  permanent,  enormous,  and   incalculable 
practical  result"  of  Christian  miracles;  and  he  makes  use 
of  this  result  to  strengthen  his  plea  for  the  miraculous. 


356  FRAGMENTS  OF  SCIENCE. 

His  logical  warrant  for  this  proceeding  is  not  clear.  It  is 
the  method  of  science,  when  a  phenomenon  presents  itself, 
toward  the  production  of  which  several  elements  may 
contribute,  to  exclude  them  one  by  one,  so  as  to  arrive 
at  length  at  the  truly  effective  cause.  Heat,  for  example,  is 
associated  with  a  phenomenon;  we  exclude  heat,  but  the 
phenomenon  remains:  hence,  heat  is  not  its  cause.  Mag- 
netism is  associated  with  a  phenomenon;  we  exclude  rnag- 
netisnj,  but  the  phenomenon  remains:  hence,  magnetism 
is  not  its  cause.  Time,  also,  when  we  seek  the  cause  of  a 
diffusion  of  a  religion — whether  it  be  due  to  miracles,  or 
to  the  spiritual  force  of  its  founders — we  exclude  the  mir- 
acles, and,  finding  the  result  unchanged,  we  infer  that 
miracles  are  not  the  effective  cause.  This  important  ex- 
periment Mohammedanism  has  made  for  us.  It  has  lived 
and  spread  without  miracles;  and  to  assert,  in  the  face  of 
this,  that  Christianity  has  spread  because  of  miracles,  is,  I 
submit,  opposed  both  to  the  spirit  of  science  and  the  com- 
mon sense  of  mankind. 

The  incongruity  of  inferring  moral  goodness  from  mirac- 
ulous power  has  been  dwelt  upon  above;  in  another  par- 
ticular also  the  strain  put  by  Mr.  Mozley  upon  miracles  is, 
I  think,  more  than  they  can  bear.  In  consistency  with  his 
principles,  it  is  difficult  to  see  how  he  is  to  draw  from  the 
miracles  of  Christ  any  certain  conclusion  as  to  His  Divine 
nature.  He  dwells  very  forcibly  on  what  he  calls  "  the 
argument  from  experience,"  in  the  demolition  of  which  he 
takes  obvious  delight.  He  destroys  the  argument,  and 
repeats  it,  for  the  mere  pleasure  of  again  and  again  knock- 
ing the  breath  out  of  it.  Experience,  he  urges,  can  only 
deal  with  the  past;  and  the  moment  we  attempt  to  project 
experience  a  hair's  breadth  beyond  the  point  it  has  at  any 
moment  reached,  we  are  condemned  by  reason.  It  appears 
to  me  that  when  he  infers  from  Christ's  miracles  a  Divine 
and  altogether  superhuman  energy,  Mr.  Mozley  places  him- 
self precisely  under  this  condemnation.  For  what  is  his 
logical  ground  for  concluding  that  the  miracles  of  the  New 
Testament  illustrate  Divine  power?  May  they  not  be  the 
result  of  expanded  human  power?  A  miracle  he  defines  as 
something  impossible  to  man.  But  how  does  he  know  that 
the  miracles  of  the  New  Testament  are  impossible  to  man? 
Seek  as  he  may,  he  has  absolutely  no  reason  to  adduce  save 
this — that  man  has  never  hitherto  accomplished  such 


MIRACLES  AND  SPECIAL  PROVIDENCES.        35? 

things.  But  does  the  fact  that  man  has  never  raised  the 
dead  prove  that  he  can  never  raise  the  dead?  "Assuredly 
not,"  must  be  Mr.  Mozley's  reply;  "for  this  would  be 
pushing  experience  beyond  the  limit  it  has  now  reached — 
which  I  pronounce  unlawful/'  Then  a  period  may  come 
when  man  will  be  able  to  raise  the  dead.  If  this  be  con- 
ceded— and  I  do  not  see  how  Mr.  Mozley  can  avoid  the  con- 
cession— it  destroys  the  necessity  of  inferring  Christ's 
divinity  from  His  miracles.  He.  it  may  be  contended, 
antedated  the  humanity  of  the  future;  as  a  mighty  tidal 
wave  leaves  high  upon  the  beach  a  mark  which  by  and  by 
becomes  the  general  level  of  the  ocean.  Turn  the  matter  as 
you  will,  no  other  warrant  will  be  found  for  the  all-impor- 
tant conclusion  that  Christ's  miracles  demonstrate  divine 
power,  than  an  argument  which  has  been  stigmatized 
by  Mr.  Mozley  as  a  "  rope  of  sand" — the  argument  from 
experience. 

The  learned  Bampton  lecturer  would  be  in  this  position, 
even  had  he  seen  with  his  own  eyes  every  miracle  recorded 
in  the  New  Testament.  But  he  has  not  seen  these  mira- 
cles; and  his  intellectual  plight  is  therefore  worse.  He 
accepts  these  miracles  on  testimony.  Why  does  he  believe 
that  testimony?  How  does  he  know  that  it  is  not 
delusion;  how  is  he  sure  that  it  is  not  even  fraud?  He  will 
answer,  that  the  writing  bears  the  marks  of  sobriety  and 
truth:  and  that  in  many  cases  the  bearers  of  this  message 
to  mankind  sealed  it  with  their  blood.  Granted  with  all 
my  heart;  but  whence  the  value  of  all  this?  Is  it  not 
solely  derived  from  the  fact  that  men,  as  we  know  them, 
do  not  sacrifice  their  lives  in  the  attestation  of  that  which 
they  know  to  be  untrue?  Does  not  the  entire  value  of  the 
testimony  of  the  apostles  depend  ultimately  upon  onr  ex- 
perience of  human  nature?  It  appears,  then,  that  those 
said  to  have  seen  the  miracles  based  their  inferences  from 
what  they  saw  on  the  argument  from  experience;  and  that 
Mr.  Mozley  bases  his  belief  in  their  testimony  on  the  same 
argument.  The  weakness  of  his  conclusion  is  quadrupled 
by  this  double  insertion  of  a  principle  of  belief,  to  which 
he  flatly  denies  rationality.  His  reasoning,  in  fact,  cuts 
two  ways — if  it  destroys  our  trust  in  the  order  of  nature,  it 
far  more  effectually  abolishes  the  basis  on  which  Mr. 
Mozley  seeks  to  found  the  Christian  religion. 


358  FRAGMENTS  OF  SCIENCE. 

Over  this  argument,  from  experience,  which  at  bottom 
is  his  argument,  Mr.  Mozley  rides  roughshod.  There  is  a 
dash  of  scorn  in  the  energy  with  which  he  tramples  on  it. 
Probably  some  previous  writer  had  made  too  much  of  it, 
and  thus  invited  his  powerful  assault.  Finding  the  diffi- 
culty of  belief  in  miracles  to  rise  from  their  being  in  con- 
tradiction to  the  order  of  nature,  he  sets  himself  to  examine 
the  grounds  of  our  belief  in  that  order.  With  a  vigor  of 
logic  rarely  equaled,  and  with  a  confidence  in  its  con- 
clusions never  surpassed,  he  disposes  of  this  belief  in  a 
manner  calculated  to  startle  those  who,  without  due  exam- 
ination, had  come  to  the  conclusion  that  the  order  of 
nature  was  secure. 

What  we  mean,  he  says,  by  our  belief  in  the  order  of 
nature,  is  the  belief  that  the  future  will  be  like  the  past. 
There  is  not,  according  to  Mr.  Mozley,  the  slightest  rational 
basis  for  this  belief. 

"  That  any  cause  in  nature  is  more  permanent  than  its  existing  and 
known  effects,  extending  further,  and  about  to  produce  other  and 
more  instances  besides  what  it  has  produced  already,  we  have  no 
evidence.  Let  us  imagine,"  he  continues,  "  the  occurrence  of  a  par- 
ticular physical  phenomenon  for  the  first  time.  Upon  that  single 
occurrence  we  should  have  but  the  very  faintest  expectation  of  an- 
other. If  it  did  occur  again,  once  or  twice,  so  far  from  counting  on 
another  occurrence,  a  cessation  would  occur  as  the  most  natural  event 
to  us.  But  let  it  continue  one  hundred  times,  and  we  should  find  no 
hesitation  in  inviting  persons  from  a  distance  to  see  it;  and  if  it 
occurred  every  day  for  years,  its  occurrence  would  be  a  certainty  to 
us,  its  cessation  a  marveh  .  .  .What  ground  of  reason  can  we 
assign  for  an  expectation  that  any  part  of  the  course  of  nature  will  be 
the  next  moment  what  it  has  been  up  to  this  moment,  i.e.,  for  our 
belief  in  the  uniformity  of  nature?  None.  No  demonstrative  reason 
can  be  given,  for  the  contrary  to  the  recurrence  of  a  fact  of  nature  is 
no  contradiction.  No  probable  reason  can  be  given;  for  all  probable 
reasoning  respecting  the  course  of  nature  is  founded  upon  this 
presumption  of  likeness,  and  therefore  cannot  be  the  foundation  of 
it.  No  reason  can  be  given  for  this  belief.  It  is  without  a  reason. 
It  rests  upon  no  rational  grounds  and  can  be  traced  to  no  rational 
principle." 

"  Everything/'  Mr.  Mozley,  however,  adds,  "  depends 
upon  this  belief,  every  provision  we  make  for  the  future, 
every  safeguard  and  caution  we  employ  against  it,  all  cal- 
culation, all  adjustment  of  means  to  ends,  supposes  this 
belief;  and  yet  this  belief  has  no  more  producible  reason 
for  it  than  a  speculation  of  fancy.  ...  It  is  necessary, 


MIRACLES  AND  SPECIAL  PROVIDENCES.       359 

all -important  for  the  purposes  of  life,  but  solely  practical, 
ami  possesses  no  intellectual  character.  .  .  .  The 
proper  function,"  continues  Mr.  Mozlev,  "  of  the  inductive 
principle,  the  argument  from  experience,  the  belief  in  the 
order  of  nature — by  whatever  phrase  we  designate  the 
same  instinct — is  to  operate  as  a  practical  basis  for  the 
affairs  of  life  and  the  carrying  on  of  human  society/'  To 
sum  up,  the  belief  in  the  order  of  nature  is  general,  but  it 
is  "  an  unintelligent  impulse,  of  which  we  can  give  no 
rational  account."  It  is  inserted  into  our  constitution 
solely  to  induce  us  to  till  our  fields,  to  raise  our  winter 
fuel,  and  thus  to  meet  the  future  on  the  perfectly 
gratuitous  supposition  that  it  will  be  like  the  past. 

"  Thus,  step  by  step,"  says  Mr.  Mozley,  with  the  em- 
pkasis  of  a  man  who  feels  his  position  to  be  a  strong  one, 
"  has  philosophy  loosened  the  connection  of  the  order  of 
nature  with  the  ground  of  reason,  befriending  in  exact 
proportion  as  it  has  done  this  the  principle  of  miracles." 
For  "  this  belief  not  having  itself  a  foundation  in  reason, 
the  ground  is  gone  upon  which  it  could  be  maintained 
that  miracles,  as  opposed  to  the  order  of  nature,  are 
opposed  to  reason."  When  we  regard  this  belief  in  con- 
nection with  science,  "  in  which  connection  it  receives  a 
more  imposing  name,  and  is  called  the  inductive  principle," 
the  result  is  the  same.  "  The  inductive  principle  is  only 
this  unreasoning  impulse  applied  to  a  scientifically  ascer- 
tained fact.  .  .  .  Science  has  led  up  to  the  fact;  but 
there  it  stops,  and  for  converting  this  fact  into  a  law,  a 
totally  unscientific  principle  comes  into  play,  the  same  as 
that  which  generalizes  the  commonest  observation  of 
nature." 

The  eloquent  pleader  of  the  cause  of  miracles  passes  over 
without  a  word  the  results  of  scientific  investigation,  as 
proving  anything  rational  regarding  the  principles  or 
method  by  which  such  results  have  been  achieved.  Here,. 
as  elsewhere,  he  declines  the  test,  "By  their  fruits  shall 
ye  know  them."  Perhaps  our  best  way  of  proceeding  will 
be  to  give  one  or  two  examples  of  the  "mode  in  which  men 
of  science  apply  the  unintelligent  impulse  with  which  Mr. 
Mozley  credits  them,  and  which  shall  show,  by  illustration, 
the  surreptitious  method  whereby  they  climb  from  the  region 
of  facts  to  that  of  laws. 

Before  the  sixteenth  century  it  was  known  that  water 


360  FRAGMENTS  OF  SCIENCE. 

rises  in  a  pump;  the  effect  being  then  explained  by  the 
maxim  that  "  Nature  abhors  a  vacuum/'  It  was  not  known 
that  there  was  any  limit  to  the  height  to  which  the  water 
would  ascend,  until,  on  one  occasion,  the  gardeners  of 
Florence,  while  attempting  to  raise  water  to  a  very  great 
elevation,  found  that  the  column  ceased  at  a  height  of 
thirty-two  feet.  Beyond  this  all  the  skill  of  the  pump- 
maker  could  not  get  it  to  rise.  The  fact  was  brought  to 
the  notice  of  Galileo,  and  he,  soured  by  a  world  which  had 
not  treated  his  science  over  kindly,  is  said  to  have  twitted 
the  philosophy  of  the  time  by  remarking  that  nature 
evidently  abhorred  a  vacuum  only  to  a  height  of  thirty- 
two  feet.  Galileo,  however,  did  not  solve  the  problem. 
It  was  taken  up  by  his  pupil  Torricelli,  to  whom,  after 
due  pondering,  the  thought  occurred,  that  the  water  might 
be  forced  into  the  tube  by  a  pressure  applied  to  the  surface 
of  the  liquid  outside.  But  where,  under  the  actual  circum- 
stances, was  such  a  pressure  to  be  found?  After  much 
reflection,  it  flashed  upon  Torricelli  that  the  atmosphere 
might  possibly  exert  this  pressure;  that  the  impalpable  air 
might  possess  weight,  and  that  a  column  of  water  thirty- 
two  feet  high  might  be  of  the  exact  weight  necessary  to 
hold  the  pressure  of  the  atmosphere  in  equilibrium. 

There  is  much  in  this  process  of  pondering  and  its  results 
which  it  is  impossible  to  analyze.  It  is  by  a  kind  of  inspira- 
tion that  we  rise  from  the  wise  and  sedulous  contemplation 
of  facts  to  the  principles  on  which  they  depend.  The  mind 
is,  as  it  were,  a  photographic  plate,  which  is  gradually 
cleansed  by  the  effort  to  think  rightly,  and  which,  when 
so  cleansed,  and  not  before,  receives  impressions  from  the 
light  of  truth.  This  passage  from  facts  to  principles  is 
called  induction;  and  induction,  in  its  highest  form,  is,  as 
I  have  just  stated,  a  kind  of  inspiration.  But,  to  make  it 
sure,  the  inward  sight  must  be  shown  to  be  in  accordance 
•  with  outward  fact.  To  prove  or  disprove  the  induction, 
we  must  resort  to  deduction  and  experiment. 

Torricelli  reasoned  thus:  If  a  column  of  water  thirty-two 
feet  high  holds  the  pressure  of  the  atmosphere  in  equi- 
librium, a  shorter  column  of  a  heavier  liquid  ought  to  do 
the  same.  Now,  mercury  is  thirteen  times  heavier  than 
water;  hence,  if  my  induction  be  correct,  the  atmosphere 
ought  to  be  able  to  sustain  only  thirty  inches  of  mercury. 
Here,  then,  is  a  deduction  which  can  be  immediately  sub- 


MIRACLES  AND  SPECIAL  PROVIDENCES.      361 

mitted  to  experiment.  Torricelli  took  a  glass  tube  a  yard 
or  so  in  length,  closed  at  one  end  and  open  at  the  other, 
and  filling  it  with  mercury,  he  stopped  the  open  end  with 
his  thumb,  and  inverted  it  into  a  basin  filled  with  the 
liquid  metal.  One  can  imagine  the  feeling  with  which 
Torricelli  removed  his  thumb,  and  the  delight  he  experi- 
enced on  finding  that  his  thought  had  forestalled  a  fact 
never  before  revealed  to  human  eyes.  The  column  sank, 
but  it  ceased  to  sink  at  a  height  of  thirty  inches,  leaving 
the  Torricellian  vacuum  overhead.  From  that  hour  the 
theory  of  the  pump  was  established. 

The  celebrated  Pascal  followed  Torricelli  with  another 
deduction.  He  reasoned  thus:  if  the  mercurial  column  be 
supported  by  the  atmosphere,  the  higher  we  ascend  in  the 
air,  the  lower  the  column  ought  to  sink,  for  the  less  will 
be  the  weight  of  the  air  overhead.  He  caused  a  friend  to 
ascend  the  Puy  de  Ddme,  carrying  with  him  a  barometric 
column;  and  it  was  found  that  during  the  ascent  the  column 
sank,  and  that  during  the  subsequent  descent  the  column 
rose.  Between  the  time  here  referred  to  and  the  present, 
millions  of  experiments  have  been  made  upon  this  subject. 
Every  village  pump  is  an  apparatus  for  such  experiments. 
In  thousands  of  instances,  moreover,  pumps  have  refused 
to  work:  but  on  examination  it  has  infallibly  been  found 
that  the  well  was  dry,  that  the  pump  required  priming,  or 
that  some  other  defect  in  the  apparatus  accounted  for  the 
anomalous  action.  In  every  case  of  the  kind  the  skill  of 
the  pump-maker  has  been  found  to  be  the  true  remedy.  In 
no  case  has  the  pressure  of  the  atmosphere  ceased;  con- 
stancy, as  regards  the  lifting  of  pump-water,  has  been 
hitherto  the  demonstrated  rule  of  nature.  So  also  as 
regards  Pascal's  experiment.  His  experience  has  been  the 
universal  experience  ever  since.  Men  have  climbed  moun- 
tains, and  gone  up  in  balloons;  but  no  deviation  from 
Pascal's  result  has  ever  been  observed.  Barometers,  like 
pumps,  have  refused  to  act;  but  instead  of  indicating  any 
suspension  of  the  operations  of  nature,  or  any  interference 
on  the  part  of  its  Author  with  atmospheric  pressure, 
examination  has  in  every  instance  fixed  the  anomaly  upon 
the  instruments  themselves.  It  is  this  welding,  then,  of 
rigid  logic  to  verifying  fact  that  Mr.  Mozley  refers  to  an 
"  unreasoning  impulse." 

Let  us  now  briefly  consider  the  case  of  Newton.     Before 


362  FRAGMENTS  OF  SVIENCti. 

his  time  men  had  occupied  themselves  with  the  problem  of 
the  solar  system.  Kepler  had  deduced,  from  a  vast  mass 
of  observations,  those  general  expressions  of  planetary 
motion  known  as  "  Kepler's  laws."  It  had  been  observed 
that  a  magnet  attracts  iron;  and  by  one  of  those  flashes  of 
inspiration  which  reveal  to  the  human  mind  the  vast  in 
the  minute,  the  general  in  the  particular,  it  had  been 
inferred,  that  the  force  by  which  bodies  fall  to  the  earth 
might  also  be  an  attraction.  Newton  pondered  all  these 
things.  He  looked,  as  was  his  wont,  into  the  darkness 
until  it  became  entirely  luminous.  How  this  light  arises 
we  cannot  explain;  but,  as  a  matter  of  fact,  it  does  arise. 
Let  me  remark  here,  that  this  kind  of  pondering  is  a  proc- 
ess with  which  the  ancients  could  have  been  but  imper- 
fectly acquainted.  They,  for  the  most  part,  found  the 
exercise  of  fantasy  more  pleasant  than  careful  observation, 
and  subsequent  brooding  over  facts.  Hence  it  is,  that 
when  those  whose  education  has  been  derived  from  the 
ancients  speak  of  "  the  reason  of  man/'  they  are  apt  to 
omit  from  their  conception  of  reason  one  of  its  most  im- 
portant factors.  Well,  Newton  slowly  marshaled  his 
thoughts,  or  rather  they  came  to  him  while  he  "  intended 
his  mind,"  rising  like  a  series  of  intellectual  births  out  of 
chaos.  He  made  this  idea  of  attraction  his  own.  But,  to 
apply  the  idea  to  the  solar  system,  it  was  necessary  to  know 
the  magnitude  of  the  attraction,  and  the  law  of  its  varia- 
tion with  the  distance.  His  conceptions  first  of  all  passed 
from  the  action  of  the  earth  as  a  whole,  to  that  of  its  con- 
stituent particles.  And  persistent  thought  brought  more 
and  more  clearly  out  the  final  conclusion,  that  every  par- 
ticle of  matter  attracts  every  other  particle  with  a  force 
varying  inversely  as  the  square  of  the  distance  between  the 
particles. 

Here  we  have  the  flower  and  outcome  of  Newton's  in- 
duction; and  how  to  verify  it,  or  to  disprove  it,  was  the 
next  question.  The  first  step  of  the  philosopher  in  this 
direction  was  to  prove,  mathematically,  that  if  this  law  of 
attraction  be  the  true  one;  if  the  earth  be  constituted  of 
particles  which  obey  this  law;  then  the  action  of  a  sphere 
equal  to  the  earth  in  size  on  a  body  outside  of  it,  is  the 
same  as  that  which  would  be  exerted  if  the  whole  mass  of 
the  sphere  were  contracted  to  a  point  at  its  center.  Prac- 
tically speaking,  then,  the  center  of  the  earth  is  the  point 


MIRACLES  AND  SPECIAL  PROVIDENCES.        363 

from  which  distances  must  be  measured  to  bodies  attracted 
by  the  earth. 

From  experiments  executed  before  his  time,  Newton 
knew  the  amount  of  the  earth's  attraction  at  the  earth's 
surface,  or  at  a  distance  of  4,000  miles  from  its  center. 
His  object  now  was  to  measure  the  attraction  at  a  greater 
distance,  and  thus  to  determine  the  law  of  its  diminution. 
But  how  was  he  to  find  a  body  at  a  sufficient  distance? 
He  had  no  balloon?  and  even  if  he  had.  he  knew  that  any 
height  to  which  he  could  attain  would  be  too  small  to 
enable  him  to  solve  his  problem.  What  did  he  do?  He 
fixed  his  thoughts  upon  the  moon — a  body  240,000  miles, 
or  sixty  times  the  earth's  radius,  from  the  earth's  center. 
He  virtually  weighed  the  moon,  and  found  that  weight  to 
be  one  thirty-six  hundredth  of  what  it  would  be  at  the  earth's 
surface.  This  is  exactly  what  his  theory  required.  I  will 
not  d  well  here  upon  the  pause  of  Newton  after  his  first  calcula 
tions,  or  speak  of  his  self-denial  in  withholding  them  because 
they  did  not  quite  agree  with  the  observations  then  at  his 
command.  Newton's  action  in  this  matter  is  the  normal 
action  of  the  scientific  mind.  If  it  were  otherwise — if 
scientific  men  were  not  accustomed  to  demand  verification 
— if  they  were  satisfied  with  the  imperfect  while  the  perfect 
is  attainable,  their  science,  instead  of  being,  as  it  is,  a 
fortress  of  adamant,  would  be  a  house  of  clay,  ill-fitted  to 
bear  the  buffetiugs  of  the  theologic  storms  to  which  it  is 
periodically  exposed. 

Thus  we  see  that  Newton,  like  Torricelli,  first  pondered 
his  facts,  illuminated  them  with  persistent  thought,  and 
finally  divined  the  character  of  the  force  of  gravitation. 
But,  having  thus  traveled  inward  to  the  principle,  he 
reversed  his  steps,  carried  the  principle  outward,  and 
justified  it  by  demonstrating  its  fitness  to  external  nature. 

And  here,  in  passing,  I  would  notice  a  point  which  is 
well  worthy  of  attention.  Kepler  had  deduced  his  laws 
from  observation.  As  far  back  as  those  observations 
extended,  the  planetary  motions  had  obeyed  these  laws; 
and  neither  Kepler  nor  Newton  entertained  a  doubt  as  to 
their  continuing  to  obey  them.  Year  after  year,  as  the 
ages  rolled,  they  believed  that  those  laws  would  continue 
to  illustrate  themselves  in  the  heavens.  But  'this  was  not 
sufficient.  The  scientific  mind  can  find  no  repose  in  the 
mere  registration  of  sequence  in  nature.  The  further 


3  64  fttA  GMENTS  OP  SCIENCE. 

question  intrudes  itself  with  resistless  might,  Whence 
comes  the  sequence?  What  is  it  that  binds  the  consequent 
to  its  antecedent  in  nature?  The  truly  scientific  intellect 
never  can  attain  rest  until  it  reaches  the  forces  by  which 
the  observed  succession  is  produced.  It  was  thus  with 
Torricelli;  it  was  thus  with  Newton;  it  is  thus  pre-emi- 
nently with  the  scientific  man  of  to-day.  In  common  with 
the  most  ignorant,  he  shares  the  belief  that  spring  will 
succeed  winter,  that  summer  will  succeed  spring,  that 
autumn  will  succeed  summer,  and  that  winter  will  succeed 
autumn.  But  he  knows  still  further — and  this  knowledge 
is  essential  to  his  intellectual  repose — that  this  succession, 
besides  being  permanent,  is,  under  the  circumstances, 
necessary;  that  the  gravitating  force  exerted  between  the 
sun  and  a  revolving  sphere,  with  an  axis  inclined  to  the 
plane  of  its  orbit,  must  produce  the  observed  succession  of 
the  seasons.  Not  until  this  relation  between  forces  and 
phenomena  has  been  established,  is  the  law  of  reason  ren- 
dered concentric  with  the  law  of  nature;  and  not  until 
this  is  effected  does  the  mind  of  the  scientific  philosopher 
rest  in  peace. 

The  expectation  of  likeness,  then,  in  the  procession  of 
phenomena,  is  not  that  on  which  the  scientific  mind  founds 
its  belief  in  the  order  of  nature.  If  the  force  be  perma- 
nent the  phenomena  are  necessary,  whether  they  resemble 
or  do  not  resemble  anything  that  lias  gone  before.  Hence, 
in  judging  of  the  order  of  nature,  our  inquiries  eventually 
relate  to  the  permanence  of  force.  From  Galileo  to  New- 
ton, from  Newton  to  our  own  time,  eager  eyes  have  been 
scanning  the  heavens,  and  clear  heads  have  been  ponder- 
ing the  phenomena  of  the  solar  system.  The  same  eyes 
and  minds  have  been  also  observing,  experimenting,  and 
reflecting  on  the  action  of  gravity  at  the  surface  of  the 
earth.  Nothing  has  occurred  to  indicate  that  the  operation 
of  the  law  has  for  a  moment  been  suspended;  nothing  has 
ever  intimated  that  nature  has  been  crossed  by  spontaneous 
action,  or  that  a  state  of  things  at  any  time  existed  which 
could  not  be  rigorouslv  deduced  from  the  preceding 
state. 

Given  the  distribution  of  matter,  and  the  forces  in  oper- 
ation, in  the'timeof  Galileo,  the  competent  mathematician 
of  that  day  could  predict  what  is  now  occurring  in  our 
own.  We  calculate  eclipses  in  advance,  and  find  our  cal- 


MIRACLES  AND  SPECIAL  PRO  V1DENCES.        365 

culations  true  to  the  second.  We  determine  the  dates  of 
those  that  have  occurred  in  the  early  times  of  history,  and 
find  calculation  and  history  in  harmony.  Anomalies  and 
perturbations  in  the  planets  have  been  over  and  over  again 
observer!;  but  these,  instead  of  demonstrating  any  incon- 
stancy on  the  part  of  natural  law,  have  invariably  been 
reduced  to  consequences  of  that  law.  Instead  of  referring 
the  perturbations  of  Uranus  to  any  interference  on  the 
part  of  the  Author  of  nature  with  the  law  of  gravitation, 
the  question  which  the  astronomer  proposed  to  himself 
wa-s,  "  How,  in  accordance  with  this  law,  can  the  pertur- 
bation be  produced?"  Guided  by  a  principle,  he  was  en- 
abled to  fix  the  point  of  space  in  which,  if  a  mass  of  mat- 
ter were  placed,  the  observed  perturbations  would  follow. 
We  know  the  result.  The  practical  astronomer  turned  his 
telescope  toward  the  region  which  the  intellect  of  the 
theoretic  astronomer  had  already  explored,  and  the  planet 
now  named  Neptune  was  found  in  its  predicted  place.  A 
very  respectable  outcome,  it  will  be  admitted,  of  an  impulse 
which  "  rests  upon  uo  rational  grounds,  and  can  be  traced 
to  no  rational  principle;"  which  possesses  "  no  intellectual 
character;"  which  "  philosophy  "  has  uprooted  from  "  the 
ground  of  reason,"  and  fixed  in  that  "  large  irrational  de- 
partment "  discovered  for  it,  by  Mr.  Mozley,  in  the  hitherto 
unexplored  wilderness  of  the  human  mind. 

The  proper  function  of  the  inductive  principle,  or  the 
belief  in  the  order  of  nature,  says  Mr.  Mozley,  is  "  to  act 
as  a  practical  basis  for  the  affairs  of  life,  and  the  carrying 
on  of  human  society."  But  what,  it  may  be  asked,  has 
the  planet  Neptune,  or  the  belts  of  Jupiter,  or  the  white- 
ness about  the  poles  of  Mars,  to  do  with  the  affairs  of 
society?  How  is  society  affected  by  the  fact  that  the  sun's 
atmosphere  contains  sodium,  or  that  the  nebula  of  Orion 
contains  hydrogen  gas?  Nineteen-twentieths  of  the  force 
employed  in  the  exercise  of  trie  inductive  principle,  which, 
reiterates  Mr.  Mozley,  is  "  purely  practical,"  have  been 
expended  upon  subjects  as  unpractical  as  these.  What 
practical  interest  has  society  in  the  fact  that  the  spots  on 
the  sun  have  a  decennial  period,  and  that  when  a  magnet 
is  closely  watched  for  half  a  century,  it  is  found  to  perform 
small  motions  which  synchronize  with  the  appearance  and 
disappearance  of  the  solar  spots?  And  yet,  I  doubt  not, 
Sir  Edward  Sabiue  would  deem  a  life  of  intellectual  toil 


366  FRAGMENTS  OF  SCIENCE. 

amply  rewarded  by  being  privileged  to  solve,  at  its  close, 
these  infinitesimal  motions. 

The  inductive  principle  is  founded  in  man's  desire  to 
know — a  desire  arising  fro  in  his  position  among  phenomena 
which  are  reducible  to  order  by  his  intellect.  The  material 
universe  is  the  complement  of  the  intellect;  and,  without 
the  study  of  its  laws,  reason  could  never  have  awakened  to 
the  higher  forms  of  self-consciousness  at  all.  It  is  the 
Non-ego  through  and  by  which  the  Ego  is  endowed  with 
self-discernment.  AVe  hold  it  to  be  an  exercise  of  reason 
to  explore  the  meaning  of  a  universe  to  which  we  stand 
in  this  relation,  and  the  work  we  have  accomplished  is  the 
proper  commentary  on  the  methods. we  have  pursued. 
Before  these  methods  were  adopted  the  unbridled  imag- 
ination roamed  through  nature,  putting  in  the  place  of 
law  the  figments  of  superstitious  dread.  For  thousands 
of  years  witchcraft,  and  magic,  and  miracles,  and  special 
providences,  and  Mr.  Mozley's  "  distinctive  reason  of  man," 
had  the  world  to  themselves.  They  made  worse  than 
nothing  of  it — worse,  I  say,  because  they  let  and  hindered 
those  who  might  have  made  something  of  it.  Hence  it  is, 
that  during  a  single  lifetime  of  this  era  of  "  unintelligent 
impulse,"  the  progress  in  knowledge  is  all  but  infinite  as 
compared  with  that  of  the  ages  which  preceded  ours. 

The  believers  in  magic  and  miracles  of  a  couple  of  cen- 
turies ago  had  all  the  strength  of  Mr.  Mozley's  present 
logic  on  their  side.  They  had  done  for  themselves  what 
he  rejoices  in  having  so  effectually  done  for  us — cleared 
the  ground  of  the  belief  in  theorder  of  nature,  and  declared 
magic,  miracles,  and  witchcraft  to  be  matters  for  "  ordinary 
evidence"  to  decide.  "The  principle  of  miracles"  thus 
"befriended"  had  free  scope,  and  we  know  the  result. 
Lacking  that  rock-barrier  of  natural  knowledge  which  we 
now  possess,  keen  jurists  and  cultivated  men  were  hurried 
on  to  deeds,  the  bare  recital  of  which  makes  the  blood  run 
cold.  Skilled  in  all  the  rules  of  human  evidence,  and 
versed  in  all  the  arts  of  cross-examination,  these  men, 
nevertheless,  went  systematically  astray,  and  committed 
the  deadliest  wrongs  against  humanity.  And  why?  Be- 
cause they  could  not  put  Na,ture  into  the  witness-box,  and 
question  her — of  her  voiceless  "testimony"  they  knew 
nothing.  In  all  cases  between  man  and  man,  their  judg- 


MIRACLES  AND  SPECIAL  PROVIDENCES.        367 

ment  was  to  be  relied  on;  but  in  all  cases  between  man 
and  nature,  they  were  blind  leaders  of  the  blind.* 

Mr.  Mozley  concedes  that  it  would  be  no  great  result  if 
miracles  were  only  accepted  by  the  ignorant  and  super- 
stitious, "because  it  is  easy  to  satisfy  those  who  do  not 
inquire."  But  he  does  consider  it  "a  great  result"  that 
they  have  been  accepted  by  the  educated.  In  what  sense 
educated?  Like  those  statesmen,  jurists,  and  church 
dignitaries  whose  education  was  unable  to  save  them  from 
the  frightful  errors  glanced  at  above?  Not  even  in  this 
sense;  for  the  great  mass  of  Mr.  Mozley's  educated  people 
had  no  legal  training,  and  must  have  been  absolutely 
defenseless  against  delusions  which  could  set  even  that 
training  at  naught.  Like  nine-tenths  of  our  clergy  at  the 
present  day,  they  were  versed  in  the  literature  of  Greece, 
Rome,  and  Judea;  but  as  regards  a  knowledge  of  nature, 
which  is  here  the  one  thing  needful,  they  were  "noble 
savages,"  and  nothing  more.  In  the  case  of  miracles,  then, 
it  behoves  us  to  understand  the  weight  of  the  negative, 
before  we  assign  a  value  to  the  positive;  to  comprehend 
the  depositions  of  nature,  before  we  attempt  to  measure, 
with  them,  the  evidence  of  men.  We  have  only  to  open 
our  eyes  to  see  what  honest  and  even  intellectual  men  and 
women  are  capable  of,  as  to  judging  evidence,  in  this  nine- 
teenth century  of  the  Christian  era,  and  in  latitude  fifty- 
two  degrees  north.  The  experience  thus  gained  ought,  I 
imagine,  to  influence  our  opinion  regarding  the  testimony 
of  people  inhabiting  a  sunnier  clime,  with  a  richer  imagi- 
nation, and  without  a  particle  of  that  restraint  which  the 
discoveries  of  physical  science  have  imposed  upon  man- 
kind. 

Having  thus  submitted  Mr.  Mozley's  views  to  the  exam- 
ination which  they  challenged  at  the  hands  of  a  student  of 
nature,  I  am  unwilling  to  quit  his  book  without  expressing 

*  "  In  1664  two  women  were  hung  in  Suffolk,  under  a  sentence  of 
Sir  Matthew  Hale,  who  took  the  opportunity  of  declaring  that  the 
reality  of  witchcraft  was  unquestionable;  '  for  first,  the  Scrip- 
tures had  affirmed  so  much;  and  secondly,  the  wisdom  of  all  nations 
had  provided  laws  against  such  persons,  which  is  an  argument  of 
their  confidence  of  such  a  crime.'  Sir  Thomas  Browne,  who  was  a 
great  physician  as  well  as  a  great  writer,  was  called  as  a  witness, 
and  swore  '  that  he  was  clearly  of  opinion  that  the  persons  were 
bewitched. "'— Lecky's  History  of  Rationalism,  vol.  i.,  p.  120. 


368  FRAGMENTS  OF  SCIENCE. 

my  admiration  of  his  genius,  and  my  respect  for  his  char- 
acter. Though  barely  known  to  him  personally,  his  recent 
death  affected  me  as  that  of  a  friend.  With  regard  to  the 
style  of  his  book,  I  heartily  subscribe  to  the  description 
with  which  the  Times  winds  up  its  able  and  appreciative 
review.  "  It  is  marked  throughout  with  the  most  serious 
and  earnest  conviction,  but  is  without  a  single  word  from 
first  to  last  of  asperity  or  insinuation  against  opponents; 
and  this  not  from  any  deficiency  of  feeling  as  to  the  impor- 
tance of  the  issue,  but  from  a  deliberate  and  resolutely 
maintained  self-control,  and  from  an  overruling,  ever- 
present  sense  of  the  duty,  on  themes  like  these,  of  a  more 
than  judicial  calmness." 

[To  the  argument  regarding  the  quantity  of  the  mirac- 
ulous, introduced  at  page  355,  Mr.  Mozley  has  done  me 
the  honor  of  publishing  a  reply  in  the  seventh  volume  of 
the  Contemporary  Review.— J.  T.] 


ADDITIONAL   REMARKS   ON   MIRACLES. 

AMONG  the  scraps  of  manuscript,  written  at  the  time 
when  Mr.  Mozley's  work  occupied  my  attention,  I  find  the 
following  reflections: 

With  regard  to  the  influence  of  modern  science  which 
Mr.  Mozley  rates  so  low,  one  obvious  effect  of  it  is  to 
enhance  the  magnitude  of  many  of  the  recorded  miracles, 
and  to  increase  proportionably  the  difficulties  of  belief. 
The  ancients  knew  but  little  of  the  vastness  of  the  universe. 
The  Rev.  Mr.  Kirk  man,  for  example,  has  shown  what 
inadequate  notions  the  Jews  entertained  regarding  the 
"firmament  of  heaven;"  and  Sir  George  Airy  refers  to  the 
case  of  a  Greek  philosopher  who  was  persecuted  for 
hazarding  the  assertion,  then  deemed  monstrous,  that  the 
sun  might  be  as  large  as  the  whole  country  of  Greece.  The 
concerns  of  a  universe,  regarded  from  this  point  of  view, 
were  much  more  commensurate  with  man  and  his  concerns 
than  those  of  the  universe  which  science  now  reveals  to  us; 
and  hence  that  to  suit  man's  purposes,  or  that  in  com- 
pliance with  his  prayers,  changes  should  occur  in  the  order 
of  the  universe,  was  more  easy  of  belief  in  the  ancient 
world  that  it  can  be  now.  In  the  very  magnitude  which  it 


MIRACLES  AND  SPECIAL  PROVIDENCES.        369 

assigns  to  natural  phenomena,  science  has  augmented  the 
distance  between  them  and  man,  and  increased  the  popular 
belief  in  their  orderly  progression. 

As  a  natural  consequence  the  demand  for  evidence  is 
more  exacting  than  it  used  to  be,  whenever  it  is  affirmed 
that  the  order  of  nature  has  been  disturbed.  Let  us  take 
as  an  illustration  the  miracle  by  which  the  victory  of  Joshua 
over  the  Arnorites  was  rendered  complete.  In  this  case  the 
sun  is  reported  to  have  stood  still  for  "about  a  whole  day  " 
upon  Gibeon,  and  the  moon  in  the  valley  of  Ajalon.  An 
Englishman  of  average  education  at  the  present  day  would 
naturally  demand  a  greater  amount  of  evidence  to  prove 
that  this  occurrence  took  place,  than  would  have  satisfied 
an  Israelite  in  the  age  succeeding  that  of  Joshua.  For  to 
the  one,  the  miracle  probably  consisted  in  the  stoppage  of 
a  fiery  ball  less  than  a  yard  in  diameter,  while  to  the  other 
it  would  be  the  stoppage  of  an  orb  fourteen  hundred  thou- 
sand times  the  earth  in  size.  And  even  accepting  the 
interpretation  that  Joshua  dealt  with  what  was  apparent 
merely,  but  that  what  really  occurred  was  the  suspension 
of  the  earth's  rotation,  I  think  the  right  to  exercise  a 
greater  reserve  in  accepting  the  miracle,  and  to  demand 
stronger  evidence  in  support  of  it  than  that  which  would 
have  satisfied  an  ancient  Israelite,  will  still  be  conceded  to 
a  man  of  science. 

There  is  a  scientific  as  well  as  an  historic  imagination; 
and  when,  by  the  exercise  of  the  former,  the  stoppage  of 
the  earth's  rotation  is  clearly  realized,  the  event  assumes 
proportions  so  vast,  in  comparison  with  the  result  to  be 
obtained  by  it,  that  belief  reels  under  the  reflection.  The 
energy  here  involved  is  equal  to  that  of  six  trillions  of 
horses  working  for  the  whole  of  the  time  employed  by 
Joshua  in  the  destruction  of  his  foes.  The  amount  of 
power  thus  expended  would  be  sufficient  to  supply  every 
individual  of  an  army  a  thousand  times  the  strength  of 
that  of  Joshua,  with  a  thousand  times  the  fighting  power 
of  each  of  Joshua's  soldiers,  not  for  the  few  hours  necessary 
to  the  extinction  of  a  handful  of  Arnorites,  but  for  mill- 
ions of  years.  All  this  wonder  is  silently  passed  over  by 
the  sacred  historian,  manifestly  because  he  knew  nothing 
about  it.  Whether,  therefore,  we  consider  the  miracle  as 
purely  evidential,  or  as  a  practical  means  of  vengeance,  the 
same  lavish  squandering  of  energy  stares  us  in  the  face.  If 


376  FRAGMENTS  OF  SCIENCE. 

evidential,  the  energy  was  wasted,  because  the  Israelites 
knew  nothing  of  its  amount;  if  simply  destructive,  then 
the  ratio  of  the  quantity  lost  to  the  quantity  employed,  may 
be  inferred  from  the  foregoing  figures. 

To  other  miracles  similar  remarks  apply.  Transferring 
our  thoughts  from  this  little  sand-grain  of  an  earth  to  the 
immeasurable  heavens,  where  countless  worlds  with  freights 
of  life  probably  revolve  unseen,  the  very  suns  which  warm 
them  being  barely  visible  across  abysmal  space;  reflecting 
that  beyond  these  sparks  of  solar  tire  suns  innumerable 
may  burn,  whose  light  can  never  stir  the  optic  nerve  at  all; 
and  bringing  these  reflections  face  to  face  with  the  idea  of 
the  Builder  and  Sustainer  of  it  all  showing  Himself  in  a 
burning  bush,  exhibiting  His  hinder  parts,  or  behaving  in 
other  familiar  ways  ascribed  to  Him  in  the  Jewish  Scrip- 
tures, the  incongruity  must  appear.  Did  this  credulous 
prattle  of  the  ancients  about  miracles  stand  alone;  were 
it  not  associated  with  words  of  imperishable  wisdom,  and 
with  examples  of  moral  grandeur  unmatched  elsewhere  in 
the  history  of  the  human  race,  both  the  miracles  and  their 
"evidences"  would  have  long  since  ceased  to  be  the  trans- 
mitted inheritance  of  intelligent  men.  Influenced  by  the 
thoughts  which  this  universe  inspires,  well  may  we  exclaim 
in  David's  spirit,  if  not  in  David's  words:  "  When  I  consider 
the  heavens,  the  work  of  thy  fingers,  the  moon,  and  the 
stars,  which  thou  hast  ordained;  what  is  man  that  thou 
shouldst  be  mindful  of  him,  or  the  son  of  man  that  thou 
shouldst  so  regard  him?" 

If  you  ask  me  who  is  to  limit  the  outgoings  of  Almighty 
•power,  iny  answer  is,  Not  I.  If  you  should  urge  that  if 
the  Builder  and  Maker  of  this  universe  chose  to  stop  the 
rotation  of  the  earth,  or  to  take  the  form  of  a  burning 
bush,  there  is  nothing  to  prevent  Him  from  doing  so,  I  am 
not  prepared  to  contradict  you.  I  neither  agree  with  you 
nor  differ  from  you,  for  it  is  a  subject  of  which  I  know 
nothing.  But  I  observe  that  in  such  questions  regarding 
Almighty  power,  your  inquiries  relate,  not  to  that  power 
as  it  is  actually  displayed  in  the  universe,  but  to  the  power 
of  your  own  imagination.  Your  question  is,  not  has  the 
Omnipotent  done  so  and  so?  or  is  it  in  the  least  degree 
likely  that  the  Omnipotent  should  do  so  and  so?  but,  is 
my  imagination  competent  to  picture  a  Being  able  and 
willing  to  do  so  and  so?  I  am  not  prepared  to  deny  your 


ON  PR  A  7ER  ASA  FOHM  OF  PHYSICAL  EtfERG  T.    3  71 

competeuce.  To  the  human  mind  belongs  the  faculty  of 
enlarging  and  diminishing,  of  distorting  and  combining, 
indefinitely,  the  objects  revealed  by  the  senses.  It  can 
imagine  a  mouse  as  large  as  an  elephant,  an  elephant  as 
largo  as  a  mountain,  and  a  mountain  as  high  as  the  stars. 
It  can  separate  congruities  aud  unite  incongruities.  We 
see  a  fish  and  we  see  a  woman;  we  can  drop  one  half  of 
each,  and  unite  in  idea  the  other  two  halves  to  a  mermaid. 
We  see  a  horse  and  we  see  a  man;  we  are  able  to  drop  one 
half  of  each,  and  unite  the  other  two  halves  to  a  centaur. 
Thus  also  the  pictorial  representations  of  the  Deity,  the 
bodies  and  wings  of  cherubs  and  seraphs,  the  hoofs,  horns, 
and  tail  of  the  evil  one,  the  joys  of  the  blessed,  and  the 
torments  of  the  damned,  have  been  elaborated  from  ma- 
terials furnished  to  the  imagination  by  the  senses.  It 
behoves  you  and  me  to  take  care  that  our  notions  of  the 
Power  which  rules  the  universe  are  not  mere  fanciful  or 
ignorant  enlargements  of  human  power.  The  capabilities 
of  what  you  call  your  reason  are  not  denied.  By  the  exer- 
cise of  the  faculty  here  adverted  to,  you  can  picture  to 
yourself  a  Being  able  and  willing  to  do  any  and  every  con- 
ceivable thing.  You  are  right  in  saying  that  in  opposition 
to  this  power  science  is  of  no  avail — that  it  is  "a  weapon 
of  air."  The  man  of  science,  however,  while  accepting 
the  figure,  would  probably  reverse  its  application,  thinking 
it  is  not  science  which  is  here  the  thing  of  air,  but  that 
unsubstantial  pageant  of  the  imagination  to  which  the 
solidity  of  science  is  opposed. 


CHAPTER  XXV. 

ON   PRAYER   AS   A   FORM   OF   PHYSICAL   ENERGY. 

Prayer  as  a  means  to  effect  a  private  end  is  theft  and  meanness. — 
EMERSON. 

THE  EDITOR  of  the  Contemporary  Revieio  is  liberal 
enough  to  grant  me  space  for  some  remarks  upon  a  subject, 
which,  though  my  relation  to  it  was  simply  that  of  a 
vehicle  of  transmission,  has  brought  down  upon  me  a  con- 
siderable amount  of  animadversion. 

It  may  be  interesting  to  some  of  my  readers  if  I  glance 
at  a  few  cases  illustrative  of  the  history  of  the  human 


372  FRAGMENTS, OF  SCIENCE. 

mind,  in  relation  to  this  and  kindred  questions.  In  the 
fourth  century  the  belief  in  Antipodes  was  deemed 
uuscriptural  and  heretical.  The  pious  Lactautius  was 
as  angry  with  the  people  who  held  this  notion  as  my  cen- 
sors are  now  with  me,  and  quite  as  unsparing  in  his 
denunciations  of  their  "Monstrosities."  Lactantius  was 
irritated  because,  in  his  mind,  by  education  and  habit, 
cosmogony  and  religion  were  indissolubly  associated,  and, 
therefore,  simultaneously  disturbed.  In  the  early  part  of 
the  seventeenth  century  the  notion  that  the  earth  was  fixed, 
and  that  the  sun  and  stars  revolved  round  it  daily,  was 
interwoven  with  religious  feeling,  the  separation  then 
attempted  by  Galileo  rousing  the  animosity  and  kindling 
the  persecution  of  the  Church.  Men  still  living  can 
remember  the  indignation  excited  by  the  first  revelations  of 
geology  regarding  the  age  of  the  earth,  the  association  be- 
tween chronology  and  religion  being  for  the  time  indissol- 
uble. In  our  day,  however,  the  best-informed  theologians 
are  prepared  to  admit  that  our  views  of  the  universe  and 
its  Author  are  not  impaired,  but  improved,  by  the  aban- 
donment of  the  Mosaic  account  of  the  creation.  Look, 
finally,  at  the  excitement  caused  by  the  publication  of  the 
"Origin  of  Species,"  and  compare  it  with  the  calm  attend- 
ant on  the  appearance  of  the  far  more  outspoken,  and, 
from  the  old  point  of  view,  more  impious,  "Descent  of 
Man." 

Thus  religion  survives  after  the  removal  of  what  had 
been  long  considered  essential  to  it.  In  our  day  the  Anti- 
podes are  accepted;  the  fixity  of  the  earth  is  given  up; 
the  period  of  creation  and  the  reputed  age  of  the  world 
are  alike  dissipated;  evolution  is  looked  upon  without 
terror;  and  other  changes  have  occurred  in  the  same  direc- 
tion too  numerous  to  be  dwelt  upon  here.  In  fact,  from 
the  earliest  times  to  the  present,  religion  has  been  under- 
going a  process  of  purification,  freeing  itself  slowly  and 
painfully  from  the  physical  errors  which  the  active  but 
uninformed  intellect  mingled  with  the  aspirations  of  the 
soul.  Some  of  us  think  that  a  final  act  of  purification  is 
needed,  while  others  oppose  this  notion  with  the  confidence 
and  the  warmth  of  ancient  times.  The  bone  of  contention 
at  present  is  the  physical  value  of  prayer.  It  is  not  my 
wish  to  excite  surprise,  much  less  to  draw  forth  protest, 
by  the  employment  of  this  phrase.  I  would  simply  ask  any 


ON  PRA  YES  AS  A  FORM  OF  PHYSICAL  ENERG  T.    373 

intelligent  person  to  look  the  problem  honestly  in  the  face, 
and  then  to  say  whether,  in  the  estimation  of  the  great 
body  of  those  who  sincerely  resort  to  it,  prayer  does  not,  at 
ail  events  upon  special  occasions,  invoke  a  power  which 
checks  and  augments  the  descent  of  rain,  which  changes 
the  force  and  direction  of  winds,  which  affects  the  growth, 
of  corn  and  the  health  of  men  and  cattle — a  Power,  in 
short,  which,  when  appealed  to  under  pressing  circum- 
stances, produces  the  precise  effects  caused  by  physical 
energy  in  the  ordinary  course  of  things.  To  any  person 
who  deals  sincerely  with  the  subject,  and  refuses  to  blur 
his  moral  vision  by  intellectual  subtleties,  this,  I  think, 
will  appear  a  true  statement  of  the  case. 

It  is  under  this  aspect  alone  that  the  scientific  student, 
so  far  as  I  represent  him,  has  any  wish  to  meddle  with 
prayer.  Forced  upon  his  attention  as  a  form  of  physical 
energy,  or  as  the  equivalent  of  such  energy,  he  claims  the 
right  of  subjecting  it  to  those  methods  of  examination 
from  which  all  our  present  knowledge  of  the  physical 
universe  is  derived.  And  if  his  researches  lead  him  to  a 
conclusion  adverse  to  its  claims — if  his  inquiries  rivet  him 
still  closer  to  the  philosophy  implied  in  the  words,  "  He 
maketh  his  sun  to  shine  on  the  evil  and  on  the  good,  and 
sendeth  rain  upon  the  just  and  upon  the  unjust" — he 
contends  only  for  the  displacement  of  prayer,  not  for  its 
extinction.  He  simply  says,  physical  nature  is  not  its 
legitimate  domain. 

This  conclusion,  moreover,  must  be  based  on  pure  phys- 
ical evidence,  and  not  on  any  inherent  unreasonableness 
in  the  act  of  prayer.  The  theory  that  the  system  of  nature 
is  under  the  control  of  a  Being  who  changes  phenomena  in 
compliance  with  the  prayers  of  men,  is,  in  my  opinion,  a 
perfectly  legitimate  one.  It  may  of  course  be  rendered 
futile  by  being  associated  with  conceptions  which  contradict 
it;  but  such  conceptions  form  no  necessary  part  of-  the 
theory.  It  is  a  matter  of  experience  that  an  earthly  father, 
who  is  at  the  same  time  both  wise  and  tender,  listens  to 
the  requests  of  his  children,  and,  if  they  do  not  ask  amiss, 
takes  pleasure  in  granting  their  requests.  We  know  also 
that  this  compliance  extends  to  the  alteration,  within  cer- 
tain limits,  of  the  current  of  events  on  earth.  With  this 
suggestion  offered  by  experience,  it  is  no  departure  from 
scientific  method  to  place  behind  natural  phenomena  a 


374  FRAGMENTS  OF  SCIENCE. 

Universal  Father,  who,  in  answer  to  the  prayers  of  His 
children,  alters  the  currents  of  those  phenomena.  Thus 
far  Theology  and  Science  go  hand  in  hand.  The  concep- 
tion of  an  ether,  for  example,  trembling  with  the  waves 
of  light,  is  suggested*  by  the  ordinary  phenomena  of  wave- 
motion  in  water  and  in  air;  and  in  like  manner  the  concep- 
tion of  personal  volition  in  nature  is  suggested  by  the 
ordinary  action  of  man  upon  earth.  I  therefore  urge  no 
impossibilities,  though  1  am  constantly  charged  with  doing 
so.  I  do  not  even  urge  inconsistency,  but,  on  the  contrary, 
frankly  admit  that  the  theologian  lias  as  good  a  right  to 
place  his  conception  at  the  root  of  phenomena  as  I  have 
to  place  mine. 

But  without  verification  a  theoretic  conception  is  a  mere 
figment  of  the  intellect,  and  I  am  sorry  to  find  us  parting 
company  at  this  point.  The  region  of  theory,  both  in 
science  and  theology,  lies  behind  the  world  of  the  senses, 
but  the  verification  of  theory  occurs  in  the  sensible  world. 
To  check  the  theory  we  have  simply  to  compare  the  deduc- 
tions from  it  with  the  facts  of  observation.  If  the  deduc- 
tions be  in  accordance  with  the  facts,  we  accept  the 
theory:  if  in  opposition,  the  theory  is  given  up.  A  single 
experiment  is  frequently  devised,  by  which  the  theory 
must  stand  or  fall.  Of  this  character  was  the  determina- 
tion of  the  velocity  of  light  in  liquids,  as  a  crucial  test  of 
the  Emission  Theory.  According  to  it,  light  traveled 
faster  in  water  than  in  air;  according  to  the  TJndulatory 
Theory,  it  traveled  faster  in  air  than  in  water.  An  exper- 
iment suggested  by  Arago,  and  executed  by  Fizeau  and 
Foucault  was  conclusive  against  Newton's  theory. 

But  while  science  cheerfully  submits  to  this  ordeal,  it 
seems  impossible  to  devise  a  mode  of  verification  of  their 
theories  which  does  not  rouse  resentment  in  theological 
minds.  Is  it  that,  while  the  pleasure  of  the  scientific  man 
culminates  in  the  demonstrated  harmony  between  theory 
and  fact,  the  highest  pleasure  of  the  religious  man  lias 
been  already  tasted  in  the  very  act  of  praying,  prior  to 
verification,  any  further  effort  in  this  direction  being  a 
mere  disturbance  of  his  peace?  Or  is  it  that  we  have  be- 
fore us  a  residue  of  that  mysticism  of  the  middle  ages,  so 
admirably  described  by  Whewell — that  "practice  of  refer- 
ring things  and  events  not  to  clear  and  distinct  notions, 
not  to  general  rules  capable  of  direct  verification,  but  to 


ON  PR  A  7ER  ASA  FORM  OF  PHYSICAL  EN  ERG  T.    3  75 

notions  vague,  distant,  and  vast,  which  we  cannot  bring 
into  contact  with  facts;  as  when  we  connect  natural  events 
with  moral  and  historic  causes."  "  Thus,"  he  continues, 
"  the  character  of  mysticism  is  that  it  refers  particulars, 
not  to  generalizations,  homogeneous  and  immediate,  but 
to  such  as  are  heterogeneous  and  remote;  to  which  we  must 
add,  that  the  process  of  this  reference  is  not  a  calm  act  of 
the  intellect,  but  is  accompanied  with  a  glow  of  enthusias- 
tic feeling." 

Every  feature  here  depicted,  and  some  more  question- 
able ones,  have  shown  themselves  of  late;  most  conspic- 
uously, I  regret  to  say,  in  the  "  leaders  "  of  a  weekly 
journal  of  considerable  influence,  and  one,  on  many 
grounds,  entitled  to  the  respect  of  thoughtful  men.  In 
the  correspondence,  however,  published  by  the  same  jour- 
nal, are  to  be  found  two  or  three  letters  well  calculated  to 
correct  the  temporary  High ti ness  of  the  journal  itself. 

It  is  not  my  habit  of  mind  to  think  otherwise  than 
solemnly  of  the  feeling  which  prompts  prayer.  It  is  a 
power  which  I  should  like  to  see  guided,  not  extinguished 
— devoted  to  practicable  objects  instead  of  wasted  upon 
air.  In  some  form  or  other,  not  yet  evident,  it  may,  as 
alleged,  be  necessary  to  man's  highest  culture.  Certain  it 
is  that,  while  I  rank  many  persons  who  resort  to  prayer 
low  in  the  scale  of  being — natural  foolishness,  bigotry,  and 
intolerance  being  in  their  case  intensified  by  the  notion 
that  they  have  access  to  the  ear  of  God — I  regard  others 
who  employ  it,  as  forming  part  of  the  very  crearn  of  the 
earth.  The  faith  that  adds  to  the  folly  and  ferocity  of  the 
one  is  turned  to  enduring  sweetness,  holiness,  abounding 
charity,  and  self-sacrifice  by  the  other.  Religion,  in  fact, 
varies  with  the  nature  upon  which  it  falls.  Often  unreason- 
able, if  not  contemptible,  prayer,  in  its  purer  forms,  hints 
at  disciplines  which  few  of  us  can  neglect  without  moral 
loss.  But  no  good  can  come  of  giving  it  a  delusive  value, 
by  claiming  for  it  a  power  in  physical  nature.  It  may 
strengthen  the  heart  to  meet  life's  losses,  and  thus 
indirectly  promote  physical  well-being,  as  the  digging  of 
JEsop's  orchard  brought  a  treasure  of  fertility  greater  than 
the  golden  treasure  sought.  Such  indirect  issues  we  all 
admit;  but  it  would  be  simply  dishonest  to  affirm  that  it  is 
such  issues  that  are  always  in  view.  Here,  for  the  present, 
I  must  end.  I  ask  no  space  to  reply  to  those  railers  who 


3?6  FRAGMENTS  OF  SCIENCE. 

make  such  free  use  of  the  terms  insolence,  outrage,  pro- 
fanity, and  blasphemy.  They  obviously  lack  the  sobriety 
of  mind  necessary  to  give  accuracy  to  their  statements,  or 
to  render  their  charges  worthy  of  serious  refutation. 


CHAPTER  XXVI. 

VITALITY. 

THE  ORIGIN",  growth,  and  energies  of  living  things  are 
subjects  which  have  always  engaged  the  attention  of  think- 
ing men.  To  account  for  them  it  was  usual  to  assume  a 
special  agent,  free  to  a  great  extent  from  the  limitations 
observed  among  the  powers  of  inorganic  nature.  This 
agent  was  called  vital  force;  and,  under  its  influence,  plants 
and  animals  were  supposed  to  collect  their  materials  and 
to  assume  determinate  forms.  Within  the  last  few  years, 
however,  our  ideas  of  vital  processes  have  undergone  pro- 
found modifications;  and  the  interest,  and  even  dis- 
quietude, which  the  change  has  excited  are  amply  evidenced 
by  the  discussions  and  protests  which  are  now  common,  re- 
garding the  phenomena  of  vitality.  In  tracing  these 
phenomena  through  all  their  modifications,  the  most 
advanced  philosophers  of  the  present  day  declare  that  they 
ultimately  arrive  at  a  single  source  of  power,  from  which 
all  vital  energy  is  derived;  and  the  disquieting  circumstance 
is  that  this  source  is  not  the  direct  fiat  of  a  supernatural 
agent,  but  a  reservoir  of  what,  if  we  do  not  accept  the 
creed  of  Zoroaster,  must  be  regarded  as  inorganic  force. 
In  short,  it  is  considered  as  proved  that  all  the  energy 
which  we  derive  from  plants  and  animals  is  drawn  from 
the  sun. 

A  few  years  ago,  when  the  sun  was  affirmed  to  be  the 
source  of  life,  nine  out  of  ten  of  those  who  are  alarmed  by 
the  form  which  this  assertion  has  latterly  assumed  would 
have  assented,  in  a  general  way,  to  its  correctness.  Their 
assent,  however,  was  more  poetic  than  scientific,  and  they 
were  by  no  means  prepared  to  see  a  rigid  mechanical 
signification  attached  to  their  words.  This,  however,  is 
the  peculiarity  of  modern  conclusions — that  there  is  no 
creative  energy  whatever  in  the  vegetable  or  animal  organ- 
ism, but  that  all  the  power  which  we  obtain  from  the 


VITALITY.  377 

muscles  of  mau  and  animals,  as  much  as  that  which  we 
develop  by  the  combustion  of  coal  or  wood,  has  been  pro- 
duced at  the  sun's  expense.  The  sun  is  so  much  the 
colder  that  we  may  have  our  fires;  he  is  also  so  much  the 
colder  that  we  may  have  our  horse-racing  and  Alpine 
climbing.  It  is,  for  example,  certain  that  the  sun  has 
been  chilled  to  an  extent  capable  of  being  accurately 
expressed  in  numbers,  in  order  to  furnish  the  power  which 
lifted  this  year  a  certain  number  of  tourists  from  the  vale 
of  Chamouni  to  the  summit  of  Mont  Blanc. 

To  most  minds,  however,  the  energy  of  light  and  heat 
presents  itself  as  a  thing  totally  distinct  from  ordinary 
mechanical  energy.  Either  of  them  can  nevertheless  be 
derived  from  the  other.  Wood  can  be  raised  by  friction 
to  the  temperature  of  ignition;  while  by  properly  striking 
a  piece  of  iron  a  skillful  blacksmith  can  cause  it  to  glow. 
Thus,  by  the  rude  agency  of  his  hammer,  he  generates 
light  and  heat.  This  action,  if  carried  far  enough,  would 
produce  the  light  and  heat  of  the  sun.  In  fact,  the  sun's 
light  and  heat  have  actually  been  referred  to  the  fall  of 
meteoric  matter  upon  his  surface;  and  whether  the  sun  is 
thus  supported  or  not,  it  is  perfectly  certain  that  he  might 
be  thus  supported.  Whether,  moreover,  the  whilom 
molten  condition  of  our  planet  was,  as  supposed  by  eminent 
men,  due  to  the  collision  of  cosmic  masses  or  not,  it  is  per- 
fectly certain  that  the  molten  condition  might  be  thus 
brought  about.  If,  then,  solar  light  and  heat  can  be  pro- 
duced by  the  impact  of  dead  matter,  and  if  from  the  light  and 
heat  thus  produced  we  can  derive  the  energies  which  we  have 
been  accustomed  to  call  vital,  it  indubitably  follows  that 
vital  energy  may  have  a  proximately  mechanical  origin. 

In  what  sense,  then,  is  the  sun  to  be  regarded  as  the 
origin  of  the  energy  derivable  from  plants  and  animals? 
Let  us  try  to  give  an  intelligible  answer  to  this  question. 
Water  may  be  raised  from  the  sea-level  to  a  high  elevation, 
and  then  permitted  to  descend.  In  descending  it  may  be 
made  to  assume  various  forms — to  fall  in  cascades,  to  spurt 
in  fountains,  to  boil  in  eddies,  or  to  flow  tranquilly  along 
a  uniform  bed.  It  may,  moreover,  be  caused  to  set  com- 
plex machinery  in  motion,  to  turn  millstones,  throw  shut- 
tles, work  saws  and  hammers,  and  drive  piles.  But  every 
form  of  power  here  indicated  would  be  derived  from  the 
original  power  expended  in  raising  the  water  to  the  height 


378  FRAGMENTS  OF  SCIENCE. 

from  which  it  fell.  There  is  no  energy  generated  by  the 
machinery:  the  work  performed  by  the  water  in  descend- 
ing is  merely  the  parceling  out  and  distribution  of  the 
work  expended  in  raising  it.  In  precisely  this  sense  is  all 
the  energy  of  plants  and  animals  the  parceling  out  and 
distribution  of  a  power  originally  exerted  by  the  sun.  In 
the  case  of  the  water,  the  source  of  the  power  consists  in 
the  forcible  separation  of  a  quantity  of  the  liquid  from  a 
low  level  of  the  earth's  surface,  and  its  elevation  to  a 
higher  position,  the  power  thus  expended  being  returned 
by  the  water  in  its  descent.  In  the  case  of  vital  phe- 
nomena, the  source  of  power  consists  in  the  forcible  sepa- 
ration of  the  atoms  of  compound  substances  by  the  sun. 
We  name  the  force  which  draws  the  water  earthward 
"  gravity," and  that  which  draws  atoms  together  "  chemical 
affinity;  "  but  these  different  names  must  not  mislead  us 
regarding  the  qualitative  identity  of  the  two  forces.  -They 
are  both  attractions;  and,  to  the  intellect,  the  falling-of 
carbon  atoms  against  oxygen  atoms  is  not  more  difficult  of 
conception  than  the  falling  of  water  to  the  earth. 

The  building  up  of  the  vegetable,  then,  is  effected  by 
the  sun,  through  the  reduction  of  chemical  compounds. 
The  phenomena  of  animal  life  are  more  or  less  complicated 
reversals  of  these  processes  of  reduction.  We  eat  the 
vegetable,  and  we  breathe  the  oxygen  of  the  air;  and  in  our 
bodies  the  oxygen,  which  had  been  lifted  from  the  carbon 
and  hydrogen  by  the  action  of  the  sun,  again  falls  toward 
them,  producing  animal  heat  and  developing  animal  forms. 
Through  the  most  complicated  phenomena  of  vitality  this 
law  runs:  the  vegetable  is  produced  while  a  weight  rises, 
the  animal  is  produced  while  a  weight  falls.  But  the  ques- 
tion is  not  exhausted  here.  The  water  employed  in  our 
first  illustration  generates  all  the  motion  displayed  in  its 
descent,  but  the  form  of  the  motion  depends  on  the  char- 
acter of  the  machinery  interposed  in  the  path  of  the  water. 
In  a  similar  way,  the  primary  action  of  the  sun's  rays  is 
qualified  by  the  atoms  and  molecules  among  which  their 
energy  is  distributed.  Molecular  forces  determine  the 
form  which  the  solar  energy  will  assume.  In  the  separation 
of  the  carbon  and  oxygen  this  energy  may  be  so  conditioned 
as  to  result  in  one  case  in  the  formation  of  a  cabbage,  and 
in  another  case  in  the  formation  of  an  oak.  So  also,  as 
regards  the  reunion  of  the  carbon  and  the  oxygen,  the 


VITALITY.  379 

molecular  machinery  through  which  the  combining  energy 
acts  may,  in  one  case,  weave  the  texture  of  a  frog,  while  in 
another  it  may  weave  the  texture  of  a  man. 

The  matter  of  the  animal  body  is  that  of  inorganic 
nature.  There  is  no  substance  in  the  animal  tissues  which 
is  not  primarily  derived  from  the  rocks,  the  water,  and  the 
air.  Are  the  forces  of  organic  matter,  then,  different  in 
kind  from  those  of  inorganic  matter?  The  philosophy  of 
the  present  day  negatives  the  question.  It  is  the  compound- 
ing, in  the  organic  world,  of  forces  belonging  equally  to  the 
inorganic,  that  constitutes  the  mystery  and  the  miracle  of 
vitality.  Every  portion  of  every  animal  body  may  be 
reduced  to  purely  inorganic  matter.  A  perfect  reversal  of 
this  process  of  reduction  would  carry  us  from  the  inorganic 
to  the  organic;  and  such  a  reversal  is  at  least  conceivable. 
The  tendency,  indeed,  of  modern  science  is  to  break  down 
the  wall  of  partition  between  organic  and  inorganic,  and  to 
reduce  both  to  the  operation  of  forces  which  are  the  same 
in  kind,  but  which  are  differently  compounded. 

Consider  the  question  of  personal  identity,  in  relation  to 
that  of  molecular  form.  Thirty-four  years  ago,  Mayer  of 
Heilbronn,  with  that  power  of  genius  which  breathes  large 
meanings  into  scanty  facts,  pointed  out  that  the  blood  was 
"  the  oil  of  the  lamp  of  life/'  the  combustion  of  which 
sustains  muscular  action.  The  muscles  are  the  machinery 
by  which  the  dynamic  power  of  the  blood  is  brought  into 
play.  Thus  the  blood  is  consumed.  But  the  whole  body, 
though  more  slowly  than  the  blood,  wastes  also,  so  that 
after  a  certain  number  of  years  it  is  entirely  renewed. 
How  is  the  sense  of  personal  identity  maintained  across 
this  flight  of  molecules?  To  man,  as  we  know  him,  matter 
is  necessary  to  consciousness;  but  the  matter  of  any  period 
may  be  all  changed,  while  consciousness  exhibits  no  solution 
of-  continuity.  Like  changing  sentinels,  the  oxygen, 
hydrogen,  and  carbon  that  depart,  seem  to  whisper  their 
secret  to  their  comrades  that  arrive,  and  thus,  while  the 
Non-ego  shifts,  the  Ego  remains  the  same.  Constancy  of 
form  in  the  grouping  of  the  molecules,  and  not  constancy 
of  the  molecules  themselves,  is  the  correlative  of  this  con- 
stancy of  perception.  Life  is  a  wave  which  in  no  two 
consecutive  moments  of  its  existence  is  composed  of  the 
same  particles. 

Supposing,  then    the  molecules    of    the  human  body, 


380  FRAGMENTS  OF  SCIENCE. 

instead  of  replacing  others,  and  thus  renewing  a  pre-existing 
form,  to  be  gathered  first  hand  from  nature  and  put  to- 
gether in  the  same  relative  positions  as  those  which  they 
occupy  in  the  body.  Supposing  them  to  have  the  self- 
same forces  and  distribution  of  forces,  the  selfsame  motions 
and  distribution  of  motions — would  this  organized  con- 
course of  molecules  stand  before  us  as  a  sentient  thinking 
being?  There  seems  no  valid  reason  to  believe  that  it 
would  not.  Or,  supposing  a  planet  carved  from  the  sun, 
set  spinning  round  an  axis,  and  revolving  round  the  sun  at 
a  distance  from  him  equal  to  that  of  our  earth,  would  one 
of  the  consequences  of  its  refrigeration  be  the  development 
of  organic  forms?  I  lean  to  the  affirmative.  Structural 
forces  are  certainly  in  the  mass,  whether  or  not  those  forces 
reach  to  the  extent  of  forming  a  plant  or  an  animal.  In 
an  amorphous  drop  of  water  lie  latent  all  the  marvels  of 
crystalline  force;  and  who  will  set  limits  to  the  possible 
play  of  molecules  in  a  cooling  planet?  If  these  statements 
startle,  it  is  because  matter  has  been  defined  and  maligned 
by  philosophers  and  theologians,  who  were  equally  unaware 
that  it  is,  at  bottom,  essentially  mystical  and  transcen- 
dental. 

Questions  such  as  these  derive  their  present  interest  in 
great  part  from  their  audacity,  which  is  sure,  in  due  time, 
to  disappear.  And  the  sooner  the  public  dread  is  abolished 
with  reference  to  sucli  questions  the  better  for  the  cause  of 
truth.  As  regards  knowledge,  physical  science  is  polar. 
In  one  sense  it  knows,  or  is  destined  to  know,  everything. 
In  another  sense  it  knows  nothing.  Science  understands 
much  of  this  intermediate  phase  of  things  that  we  call 
nature,  of  which  it  is  the  product;  but  science  knows 
nothing  of  the  origin  or  destiny  of  nature.  Who  or  what 
made  the  sun,  and  gave  his  rays  their  alleged  power?  Who 
or  what  made  and  bestowed  upon  the  ultimate  particles  of 
matter  their  wondrous  power  of  varied  interaction  ?  Science 
does  not  know:  the  mystery,  though  pushed  back  remains 
unaltered.  To  many  of  us  who  feel  that  there  are  more 
things  in  heaven  and  earth  than  are  dreamed  of  in  the 
present  philosophy  of  science,  but  who  have  been  alsq 
taught,  by  baffled  efforts,  how  vain  is  the  attempt  to  grapr 
pie  with  the  Inscrutable,  the  ultimate  fran^e  pf  mind  is 
that  of  Goethe: 


MATTER  AND  FORCE.  381 

Who  dares  to  name  His  name, 

Or  belief  in  Him  proclaim, 

Veiled  in  mystery  as  He  is,  the  All-enfolder? 

Gleams  across  the  mind  His  light, 

Feels  the  lifted  soul  His  might, 

Dare  it  then  deny  His  reign,  the  All-upholder? 


CHAPTER  XXVII. 

MATTER   AND   FORCE.* 

As  I  rode  through  the  Schwarzwald,  I  said  to  myself:  That  little 
fire  which  glows  star-like  across  the  dark-growing  moor,  where  the 
sooty  smith  bends  over  his  anvil,  and  thou  hopest  to  replace  thy  lost 
horseshoe — is  it  a  detached,  separated  speck,  cut  off  from  the  whole 
Universe;  or  indissolubly  joined  to  the  whole?  Thou  fool,  tha 
smithy  fire  was  primarily  kindled  at  the  Sun;  is  fed  by  air  that 
circulates  from  before  Noah's  Deluge,  from  beyond  the  Dogstar; 
therein,  with  Iron  Force,  and  Coal  Force,  and  the  far  stranger  Force 
of  Man,  are  cunning  affinities  and  battles  and  victories  of  Force 
brought  about;  it  is  a  little  ganglion,  or  nervous  center,  in  the 
great  vital  system  of  Immensity.  Call  it,  if  thou  wilt,  an  uncon- 
scious Altar,  kindled  on  the"  bosom  of  the  All.  .  .  .  Detached, 
separated!  I  say  there  is  no  such  separation:  nothing  hitherto 
was  ever  stranded,  cast  aside;  but  all,  were  it  only  a  withered  leaf, 
•works  together  with  all ;  is  borne  forward  on  the  bottomless, 
shoreless  Hood  of  action,  and  lives  through  perpetual  metamor- 
phoses. — C  ARLYLE. 

IT  is  the  custom  of  the  professors  in  the  Royal  School 
of  Mines  in  London  to  give  courses  of  evening  lectures 
every  year  to  workingmen.  The  lecture-room  holds  600 
people;  and  tickets  to  this  amount  are  disposed  of  as 
quickly  as  they  can  be  handed  to  those  who  apply  for  them. 
So  desirous  are  the  workingmen  of  London  to  attend  these 
lectures,  that  the  persons  who  fail  to  obtain  tickets  always 
bear  q  large  proportion  to  those  who  succeed.  Indeed,  if 
the  lecture-room  could  hold  2,000  instead  of  600,  I  do  not 
doubt  that  every  one  of  its  benches  would  be  occupied  on 
these  occasions.  It  is,  moreover,  worthy  of  remark  that 
the  lectures  are  but  rarely  of  a  character  which  could  help 
the  workingnwn  in  his  daily  pursuits.  The  information 
acquired  is  hardly  ever  of  a  nature  which  admits  of  being 
turned  into  money.  It  is,  therefore,  a  pure  desire  for 

*  A  Lecture  delivered  to  the  workingmen  of  Dundee,  September 
5,  1867,  with  additions. 


382  FRAGMENTS  OF  SCIENCE. 

knowledge,  as  a  thing  good  in  itself,  and  without  regard 
to  its  practical  application,  which  animates  the  hearers  of 
these  lectures. 

It  is  also  my  privilege  to  lecture  to  another  audience  in 
London,  composed  in  part  of  the  aristocracy  of  rank,  while 
the  audience  just  referred  to  is  composed  wholly  of  the 
aristocracy  of  labor.  As  regards  attention  and  courtesy  to 
the  lecturer,  neither  of  these  audiences  has  anything  to 
learn  of  the  other; -neither  can  claim  superiority  over  the 
other.  It  would  not,  perhaps,  be  quite  correct  to  take 
those  persons  who  flock  to  the  School  of  Mines  as  average 
samples  of  their  class;  they  are  probably  picked  men — 
the  aristocracy  of  labor,  as  I  have  just  called  them.  At 
all  events,  their  conduct  demonstrates  that  the  essential 
qualities  of  what  we  in  England  understand  by  a  gentleman 
are  confined  to  no  class;  and  they  have  often  raised  in  my 
mind  the  wish  that  the  gentlemen  of  all  classes,  artisans  as 
well  as  lords,  could,  by  some  process  of  selection,  be  sifted 
from  the  general  mass  of  the  community,  and  caused  to 
know  each  other  better. 

When  pressed  some  months  ago  by  the  Council  of  the 
British  Association  to  give  an  evening  lecture  to  the  work- 
ingmen  of  Dundee,  rny  experience  of  the  workingmen  of 
London  naturally  rose  to  my  mind;  and,  though  heavily 
weighted  with  other  duties,  I  could  not  bring  myself  to 
decline  the  request  of  the  Council.  Hitherto,  the  evening 
discourses  of  the  Association  have  been  delivered  before 
its  members  and  associates  alone.  But  after  the  meeting 
at  Nottingham,  last  year,  where  the  workingmen,  at 
their  own  request,  were  addressed  by  our  late  president, 
Mr.  Grove,  and  by  my  excellent  friend,  Professor  Huxley, 
the  idea  arose  of  incorporating  with  all  subsequent  meetings 
of  the  Association  an  address  to  the  workingmen  of  the 
town  in  which  the  meeting  is  held.  A  resolution  to  that 
effect  was  sent  to  the  Committee  of  Recommendations; 
the  Committee  supported  the  resolution;  the  Council  of 
the  Association  ratified  the  decision  of  the  Committee; 
and  here  I  am  to  carry  out  to  the  best  of  my  ability  their 
united  wishes. 

Whether  it  be  a  consequence  of  long-continued  develop- 
ment, or  an  endowment  conferred  once  for  all  on  man  at 
his  creation,  we  find  him  here  gifted  with  a  mind  curious 


MATTER  AND  FOROS.  383 

to  know  the  causes  of  things,  and  surrounded  by  objects 
•which  excite  its  questionings,  and  raise  the  desire  for  an 
explanation.  It  is  related  of  a  young  prince  of  one  of  the 
Pacific  islands,  that  when  he  first  saw  himself  in  a  looking- 
glass,  he  ran  round  the  glass  to  see  who  was  standing  at 
the  back.  And  thus  it  is  with  the  general  human  intellect, 
as  regards  the  phenomena  of  the  external  world.  It  wishes 
to  get  behind  and  learn  the  causes  and  connections  of  these 
phenomena.  What  is  the  sun,  what  is  the  earth,  what 
shod  Id  we  see  if  we  came  to  the  edge  of  the  earth  and 
looked  over?  What  is  the  meaning  of  thunder  and  light- 
ning, of  hail,  rain,  storm,  and  snow?  Such  questions 
presented  themselves  to  early  men,  and  by  and  by  it  was 
discovered  that  this  desire  for  knowledge  was  not  implanted 
in  vain.  After  many  trials  it  became  evident  that  man's 
capacities  were,  so  to  speak,  the  complement  of  nature's 
facts,  and  that,  within  certain  limits,  the  secret  of  the 
universe  was  open  to  the  human  understanding.  It  was 
found  that  the  mind  of  man  had  the  power  of  penetrating 
far  beyond  the  boundaries  of  his  five  senses;  that  the  things 
which  are  seen  in  the  material  world  depend  for  their 
action  upon  things  unseen;  in  short,  that  besides  the  phe- 
nomena which  address  the  senses,  there  are  laws  and  prin- 
ciples and  processes  which  do  not  address  the  senses  at  all, 
but  which  must  be,  and  can  be,  spiritually  discerned. 

To  the  subjects  which  require  this  discernment  belong 
the  phenomena  of  molecular  force.  But  to  trace  the 
genesis  of  the  notions  now  entertained  upon  this  subject, 
we  have  to  go  a  long  way  back.  In  the  drawing  of  a  bow, 
the  darting  of  a  javelin,  the  throwing  of  a  stone — in  the 
lifting  of  burdens,  and  in  personal  combats,  even  savage 
man  became  acquainted  with  the  operation  of  force.  Ages 
of  discipline,  moreover,  taught  him  foresight.  He  laid  by 
at  the  proper  season  stores  of  food,  thus  obtaining  time  to 
look  about  him,  and  to  become  an  observer  and  inquirer. 
Two  things  which  he  noticed  must  have  profoundly  stirred 
his  curiosity.  He  found  that  a  kind  of  resin  dropped  from 
a  certain  tree  possessed,  when  rubbed,  the  power  of  draw- 
ing light  bodies  to  itself,  and  of  causing  them  to  cling  to 
it;  and  he  had  also  found  that  a  particular  stone  exerted  a 
similar  power  over  a  particular  kind  of  metal.  I  allude,  of 
course,  to  electrified  amber,  and  to  the  loadstone,  or  natural 
magnet,  and  its  power  to  attract  particles  of  iron.  Pre- 


384  FRAGMENTS  OF  SCIENCE. 

vions  experience  of  his  own  muscles  had  enabled  our  early 
inquirer  to  distinguish  between  a  push  and  a  pull. 
Augmented  experience  showed  him  that  in  the  case  of  the 
magnet  and  the  amber  pulls  and  pushes — attractions  and 
repulsions — were  also  exerted;  and,  by  a  kind  of  poetic 
transfer,  he  applied  to  things  external  to  himself,  concep- 
tions derived  from  himself.  The  magnet  and  the  rubbed 
amber  were  credited  with  pushing  and  pulling,or,  in  other 
words,  with  exerting  force. 

In  the  time  of  the  great  Lord  Bacon  the  margin  of  these 
pushes  and  pulls  was  vastly  extended  by  Dr.  Gilbert,  a  man 
probably  of  firmer  scientific  fiber,  and  of  finer  insight, 
than  Bacon  himself.  Gilbert  proved  that  a  multitude  of 
other  bodies,  when  rubbed,  exerted  the  power  which,  thou- 
sands of  years  previously,  had  been  observed  in  amber.  In 
this  way  the  notion  of  attraction  and  repulsion  in  external 
nature  was  rendered  familiar.  It  was  a  matter  of  experi- 
ence that  bodies,  between  which  no  visible  link  or  connec- 
tion existed,  possessed  the  power  of  acting  upon  each  other; 
and  the  action  came  to  be  technically  called  "  action  at  a 
distance." 

But  out  of  experience  in  science  there  grows  something 
finer  than  mere  experience.  Experience  furnishes  the  soil 
for  plants  of  higher  growth;  and  this  observation  of  action 
at  a  distance  provided  material  for  speculation  upon  the 
largest  of  problems.  Bodies  were  observed  to  fall  to  the 
earth.  Why  should  they  do  so?  The  earth  was  proved  to 
revolve  round  the  sun;  and  the  moon  to  revolve  round  the 
earth.  Why  should  they  do  so?  What  prevents  them 
from  flying  straight  off  into  space?  Supposing  it  were 
ascertained  that  from  a  part  of  the  earth's  rocky  crust  a 
firmly  fixed  and  tightly  stretched  chain  started  toward  the 
sun,  we  might  be  inclined  to  conclude  that  the  earth  is 
held  in  its  orbit  by  the  chain — that  the  sun  twirls  the 
earth  around  him,  as  a  boy  twirls  round  his  head  a  bullet 
at  the  end  of  a  string.  But  why  should  the  chain  be 
needed?  It  is  a  fact  of  experience  that  bodies  can  attract 
each  other  at  a  distance,  without  the  intervention  of  any 
chain.  Why  should  not  the  sun  and  earth  so  attract  each 
othev?  and  why  should  not  the  fall  of  bodies  from  a  height 
be  the  result  of  their  attraction  by  the  earth?  Here  then 
we  reach  one  of  those  higher  speculations  which  grow  out 
of  the  fruitful  soil  of  observation.  Having  started  with 


MATTER  AND  FORGE.  385 

the  savage,  and  his  sensations  of  muscular  force,  we  pass 
on  to  the  observation  of  force  exerted  between  a  magnet 
and  rubbed  amber  and  the  bodies  which  they  attract, 
rising,  by  an  unbroken  growth  of  ideas,  to  a  conception  of 
the  force  by  which  sun  and  planets  are  held  together. 

This  idea  of  attraction  between  sun  and  planets  had 
become  familiar  in  the  time  of  Newton.  He  set  himself 
to  examine  the  attraction:  and  here,  as  elsewhere,  we  find 
the  speculative  mind  falling  back  for  its  materials  upon 
experience.  It  had  been  observed,  in  the  case  of  magnetic 
and  electric  bodies,  that  the  nearer  they  were  brought  to- 
gether the  stronger  was  the  force  exerted  between  them; 
while,  by  increasing  the  distance,  the  force  diminished 
until  it  became  insensible.  Hence  the  inference  that  the 
assumed  pull  between  the  earth  and  the  sun  would  be 
influenced  by  their  distance  asunder.  Guesses  had  been 
made  as  to  the  exact  manner  in  which  the  force  varied  with 
the  distance;  but  Newton  supplemented  the  guess  by  the 
severe  test  of  experiment  and  calculation.  Comparing  the 
pull  of  the  earth  upon  a  body  close  to  its  surface,  with  its 
pull  upon  the  moon,  240,000  miles  away,  Newton  rigidly 
established  the  law  of  variation  with  the  distance.  But  on 
his  way  to  this  result  Newton  found  room  for  other  con- 
ceptions, some  of  which  indeed,  constituted  the  necessary 
stepping-stones  to  his  result.  The  ona  which  here  con- 
cerns us  is,  that  not  only  does  the  sun  attract  the  earth, 
and  the  earth  attract  the  sun  as  ivholes,  but  every  particle 
of  the  sun  attracts  every  particle  of  the  earth,  and  the  re- 
verse. His  conclusion  was,  that  the  attraction  of  the 
masses  was  simply  the  sum.  of  the  attractions  of  their  con- 
stituent particles. 

This  result  seems  so  obvious  that  you  will  perhaps  wonder 
at  my  dwelling  upon  it;  but  it  really  marks  a  turning  point 
in  our  notions  of  force.  You  have  probably  heard  of 
certain  philosophers  of  the  ancient  world  named  Demoo- 
ritus,  Epicurus,  and  Lucretius.  These  men  adopted, 
developed,  and  diffused  the  doctrine  of  atoms  and  mole- 
cules, which  found  its  consummation  at  the  hands  of  the 
illustrious  John  Dalton.  But  the  Greek  and  Boman  phi- 
losophers I  have  named,  and  their  followers,  up  to  the  time 
of  Newton,  pictured  their  atoms  as  falling  and  flying 
through  space,  hitting  each  other,  and  clinging  together 
by  imaginary  hooks  and  claws.  They  missed  the  centra.' 


38G  FRAGMENTS  OF  SCIENCE. 

idea  that  atoms  and  molecules  could  come  together,  not  by 
being  fortuitously  knocked  against  each  other,  but  by 
their  own  mutual  attractions.  This  is  one  of  the  great 
steps  taken  by  Newton.  He  familiarized  the  world  with 
the  conception  of  molecular  force. 

Newton,  you  know,  was  preceded  by  a  grand  fellow 
named  John  Kepler — a  true  workingman — who,  by  analyz- 
ing the  astronomical  observations  of  his  master,  Tycho 
Brahe,  had  actually  found  that  the  planets  moved  as  they  are 
now  known  to  move.  Kepler  kuew  as  much  about  the  motion 
of  the  planets  as  Newton  did;  in  fact,  Kepler  taught  New- 
ton and  the  world  generally  the  facts  of  planetary  motion. 
But  this  was  not  enough.  The  question  arose — Why 
should  the  facts  be  so?  This  was  the  great  question  for 
Newton,  and  it  was  the  solution  of  it  which  renders  his 
name  and  fame  immortal.  Starting  from  the  principle 
that  every  particle  of  matter  in  the  solar  system  attracts 
every  other  particle  by  a  force  which  varies  as  the  inverse 
square  of  the  distance  between  the  particles,  he  proved 
that  the  planetary  motions  must  be  what  observation  makes 
them  to  be.  He  showed  that  the  moon  fell  toward  the 
earth,  and  that  the  planets  fell  toward  the  sun,  through 
the  operation  of  the  same  force  that  pulls  an  apple  from 
its  tree.  This  all-pervading  force,  which  forms  the  solder 
of  the  material  universe,  and  the  conception  of  which  was 
necessary  to  Newton's  intellectual  peace,  is  called  the  force 
of  gravitation. 

Gravitation  is  a  purely  attractive  force,  but  in  electricity 
and  magnetism,  repulsion  had  been  always  seen  to  accom- 
pany attraction.  Electricity  and  magnetism  are  double  or 
polar  forces.  In  the  case  of  magnetism,  experience  soon 
pushed  the  mind  beyond  the  bounds  of  experience,  com- 
pelling it  to  conclude  that  the  polarity  of  the  magnet  was 
resident  in  its  molecules.  1  hold  a  magnetized  strip  of 
steel  by  its  center,  and  find  that  one  half  of  the  strip  at- 
tracts, and  the  other  half  repels,  the  north  end  of  a  mag- 
netic needle.  I  break  the  strip  in  the  middle,  find  that 
this  half,  which  a  moment  ago  attracted  throughout  its 
entire  length  the  north  pole  of  a  magnetic  needle,  is  now 
divided  into  two  new  halves,  one  of  which  wholly  attracts, 
and  the  other  of  which  wholly  repels,  the  north  pole  of  the 
needle.  The  half  proves  to  be  as  perfect  a  magnet  as  the 
whole.  You  may  break  this  half  and  go  on  till  further 


MATTER  AND  FORGE.  38? 

breaking  becomes  impossible  through  the  very  smallness  of 
the  fragments;  the  smallest  fragment  is  found  endowed 
with  two  poles,  and  is,  therefore,  a  perfect  magnet.  But 
you  cannot  stop  here:  you  imagine  where  you  cannot  ex- 
periment; and  reach  the  conclusion  entertained  by  all 
scientific  men,  that  the  magnet  which  you  see  and  feel  is 
an  assemblage  of  molecular  magnets  which  you  cannot  see 
and  feel,  but  which,  as  before  stated,  must  be  intellectually 
discerned. 

Magnetism  then  is  a  polar  force;  and  experience  hints 
that  a  force  of  this  kind  may  exert  a  certain  structural 
power.  It  is  known,  for  example,  that  iron  filings  strewn 
round  a  magnet  arrange  themselves  in  definite  lines, 
called,  by  some,  "  magnetic  curves,"  and,  by  others  "  lines 
of  magnetic  force."  Over  two  magnets  now  before  me  is 
spread  a  sheet  of  paper.  Scattering  iron  filings  over  the 
paper,  polar  force  comes  into  play,  and  every  particle  of 
the  iron  responds  to  that  force.  We  have  a  kind  of  archi- 
tectural effort — if  I  may  use  the  term — exerted  on  the  part 
of  the  iron  filings.  Here  then  is  a  fact  of  experience 
which,  as  you  will  see  immediately,  furnishes  further 
material  for  the  mind  to  operate  upon,  rendering  it  possi- 
ble to  attain  intellectual  clearness  and  repose,  while 
speculating  upon  apparently  remote  phenomena. 

The  magnetic  force  has  here  acted  upon  particles  visible 
to  the  eye.  But,  as  already  stated,  there  are  numerous 
processes  in  nature  which  entirely  elude  the  eye  of  the 
body,  and  must  be  figured  by  the  eye  of  the  mind.  The 
processes  of  chemistry  are  examples  of  these.  Long  think- 
ing and  experimenting  has  led  philosophers  to  conclude 
that  matter  is  composed  of  atoms  from  which,  whether 
separate  or  in  combination,  the  whole  material  world  is 
built  up.  The  air  we  breathe,  for  example,  is  mainly  a 
mechanical  mixture  of  the  atoms  of  oxygen  and  nitrogen. 
The  water  we  drink  is  also  composed  of  oxygen  and  hydro- 
gen. But  it  differs  from  the  air  in  this  particular,  that  in 
water  the  oxygen  and  hydrogen  are  not  mechanically 
mixed,  but  chemically  combined.  The  atoms  of  oxygen 
and  those  of  hydrogen  exert  enormous  attractions  on  each 
other,  so  that  when  brought  into  sufficient  proximity  they 
rush  together  witli  an  almost  incredible  force  to  form  a 
chemical  compound.  But  powerful  as  is  the  force  with 
which  these  atoms  lock  themselves  together,  we  have  the 


388  FRAGMENTS  OF  SCIENCE. 

means  of  tearing  them  asunder,  and  the  agent  by  which 
we  accomplish  this  may  here  receive  a  few  moments' 
attention. 

Into  a  vessel  containing  acidulated  water  I  dip  two  strips 
of  metal,  the  one  being  zinc  and  the  other  platinum,  not 
permitting  them  to  touch  each  other  in  the  liquid.  I 
connect  the  two  upper  ends  of  the  strips  by  a  piece  of  cop- 
per wire.  The  wire  is  now  the  channel  of  what,  for  want 
of  a  better  name,  we  call  an  "  electric  current."  What 
the  inner  change  of  the  wire  is  we  do  not  know,  but  we  do 
know  that  a  change  has  occurred,  by  the  external  effects 
produced  by  the  wire.  Let  me  show  you  one  or  two  of 
these  effects.  Before  you  is  a  series  of  ten  vessels,  each 
with  its  pair  of  metals,  and  I  wish  to  get  the  added  force 
of  all  ten.  The  arrangement  is  called  a  voltaic  battery. 
I  plunge  a  piece  of  copper  wire  among  these  iron  filings; 
they  refuse  to  cling  to  it.  I  employ  the  selfsame  wire  to  con- 
nect the  two  ends  of  the  battery,  and  subject  it  to  the  same 
test.  The  iron  filings  now  crowd  round  the  wire  and  cling 
to  it.  I  interrupt  the  current,  and  the  filings  immediately 
fall;  the  power  of  attraction  continues  only  so  long  as  the 
wire  connects  the  two  ends  of  the  battery. 

Here  is  a  piece  of  similar  wire,  overspun  with  cotton,  to 
prevent  the  contact  of  its  various  parts,  and  formed  into  a 
coil.  I  make  the  coil  part  of  the  wire  which  connects  the 
two  ends  of  the  voltaic  battery.  By  the  attractive  force 
with  which  it  has  become  suddenly  endowed,  it  now 
empties  this  tool-box  of  its  iron  nails.  I  twist  a  covered 
copper  wire  round  this  common  poker;  connecting  the 
wire  with  the^tvvo  ends  of  the  voltaic  battery,  the  poker  is 
instantly  transformed  into  a  strong  magnet.  Two  flat 
spirals  here  are  suspended  facing  each  other,  about  six  inches 
apart.  Sending  a  current  through  both  spirals,  they  clash 
suddenly  together;  reversing  what  is  called  the  direction 
of  the  current  in  one  of  the  spirals,  they  fly  asunder.  All 
these  effects  are  due  to  the  power  which  we  name  an  elec- 
tric current,  and  which  we  figure  as  flowing  through  the 
wire  when  the  voltaic  circuit  is  complete. 

By  the  same  agent  we  tear  asunder  the  locked  atoms  of 
a  chemical  compound.  Into  this  small  cell,  containing 
water,  dip  two  thin  wires.  A  magnified  image  of  the  cell 
is  thrown  upon  the  screen  before  you,  and  you  see  plainly 
the  images  of  the  wires.  From  a*  small  battery  I  send  au 


MATTER  AND  FORCE.  38$ 

electric  current  from  wire  to  wire.  Bubbles  of  gas  rise 
immediately  from  each  of  them,  and  these  are  the  two 
gases  of  which  the  water  is  composed.  The  oxygen  is 
always  liberated  on  the  one  wire,  the  hydrogen  on  the 
other.  The  gases  may  be  collected  either  separately  or 
mixed.  I  place  upon  my  hand  a  soap  bubble  filled  with  the 
mixture  of  both  gases.  Applying  a  taper  to  the  bubble,  a 
loud  explosion  is  heard.  The  atoms  have  rushed  together 
with  detonation,  and  without  injury  to  my  hand,  and  the 
water  from  which  they  were  extracted  is  the  result  of.  their 
reunion. 

One  consequence  of  the  rushing  together  of  the  atoms  is 
the  development  of  heat.  What  is  this  heat?  Here  are 
two  ivory  balls  suspended  from  the  same  point  of  support  by 
two  short  strings.  I  draw  them  thus  apart  and  then  liber- 
ate them.  They  clash  together,  but,  by  virtue  of  their  elas- 
ticity, they  quickly  recoil,  and  a  sharp  vibratory  rattle 
succeeds  their  collision.  This  experiment  will  enable  you 
to  figure  to  your  mind  a  pair  of  clashing  atoms.  We  have 
in  the  first  place,  a  motion  of  the  one  atom  toward  the 
other — a  motion  of  translation,  as  it  is  usually  called — 
then  a  recoil,  and  afterward  a  motion  of  vibration.  To 
this  vibratory  motion  we  give  the  name  of  heat.  Thus, 
three  things  are  to  be  kept  before  the  mind — first,  the 
atoms  themselves;  secondly,  the  force  with  which  they 
attract  each  other;  and  thirdly,  the  motion  consequent 
upon  the  exertion  of  that  force.  This  motion  must  be  fig- 
ured first  as  a  motion  of  translation,  and  then  as  a  motion 
of  vibration,  to  which  latter  we  give  the  name  of  heat.  For 
some  time  after  the  act  of  combination  this  motion  is  so 
violent  as  to  prevent  the  molecules  from  coming  together, 
the  water  being  maintained  in  a  state  of  vapor.  But  as  the 
vapor  cools,  or  in  other  words  loses  its  motion,  the  mole- 
cules coalesce  to  form  a  liquid. 

And  now  we  approach  a  new  and  wonderful  display  of 
force.  As  long  as  the  substance  remains  in  a  liquid  or 
vaporous  condition,  the  play  of  this  force  is  altogether 
masked  and  hidden.  But  as  the  heat  is  gradually  with- 
drawn, the  molecules  prepare  for  new  arrangements  and 
combinations.  Solid  crystals  of  water  are  at  length  formed, 
to  which  we  give  the  familiar  name  of  ice.  Looking  at 
these  beautiful  edifices  and  their  internal  structure,  the 


390  FRAGMENTS  OF  SCIENCE. 

pondering  mind  has  forced  upon  it  the  question,  How 
are  they  built  up?  We  have  obtained  clear  conceptions  of 
polar  force;  and  we  infer  from  our  broken  magnet  that 
polar  force  may  be  resident  in  the  molecules  or  smallest 
particles  of  matter,  and  that  by  the  play  of  this  force 
structural  arrangement  is  possible.  What,  in  relation 
to  our  present  question,  is  the  natural  action  of  a  mind 
furnished  with  this  knowledge?  It  is  compelled  to  tran- 
scend experience,  and  endow  the  atoms  and  molecules  of 
which  crystals  are  built  with  definite  poles  whence  issue 
attractions  and  repulsions.  In  virtue  of  these  forces  some 
poles  are  drawn  together,  while  some  retreat  from  each 
other;  atom  is  added  to  atom,  and  molecule  to  molecule, 
not  boisterously  or  fortuitously,  but  silently  and  symmet- 
rically, and  in  accordance  with  laws  more  rigid  than  those 
which  guide  a  human  builder  when  he  places  his  materials 
together.  Imagine  the  bricks  and  stones  of  this  town  of 
Dundee  endowed  with  structural  power.  Imagine  them 
attracting  and  repelling,  and  arranging  themselves  into 
streets  and  houses  and  Kinnaird  Halls — would  not  that  be 
wonderful?  Hardly  less  wonderful  is  the  play  of  force 
by  which  the  molecules  of  water  build  themselves  into 
the  sheets  of  ice  which  every  winter  roof  your  ponds  and 
lakes. 

If  I  could  show  you  the  actual  progress  of  this  molecular 
architecture,  its  beauty  would  delight  and  astonish  you. 
A  reversal  of  the  process  of  crystallization  may  be  actually 
shown.  The  molecules  of  a  piece  of  ice  may  be  taken 
asunder  before  your  eyes;  and  from  the  manner  in  which 
they  separate  you  may  to  some  extent  infer  the  manner  in 
which  they  go  together.  When  a  beam  is  sent  from  our 
electric  lamp  through  a  plate  of  glass,  a  portion  of  the 
beam  is  intercepted  and  the  glass  is  warmed  by  the  portion 
thus  retained  within  it.  When  the  beam  is  sent  through  a 
plate  of  ice,  a  portion  of  the  beam  is  also  absorbed ;  but 
instead  of  warming  the  ice,  the  intercepted  heat  melts  it 
internally.  It  is  to  the  delicate,  silent  action  of  this  beam 
Avithin  the  ice  that  I  now  wish  to  direct  your  attention. 
Upon  the  screen  is  thrown  a  magnified  image  of  the  slab  of 
ice:  the  light  of  the  beam  passes  freely  through  the  ice 
without  melting  it,  and  enables  us  to  form  the  image;  but 
the  heat  is  in  great  part  intercepted,  and  that  heat  now 
applies  itself  to  the  work  of  internal  liquefaction.  Select- 


MATTER  AND  Fd&CR.  3^1 

ing  certain  points  for  attack,  round  about  those  points  the 
beam  works  silently,  undoing  the  crystalline  architecture, 
and  reducing  to  the  freedom  of  liquidity  molecules  which 
had  been  previously  locked  in  a  solid  embrace.  The 
liquefied  spaces  are  rendered  visible  by  strong  illumination. 
Observe  those  six-petaled  flowers  breaking  out  over  the 
white  surface,  and  expanding  in  size  as  the  action  of  the 
beam  continues.  These  flowers  are  liquefied  ice.  Under 
the  action  of  the  heat  the  molecules  of  the  crystals  fall 
asunder,  so  as  to  leave  behind  them  these  exquisite  forms, 
We  have  here  a  process  of  demolition  which  clearly  reveals 
the  reverse  process  of  construction.  In  this  fashion,  and 
in  strict  accordance  with  this  hexangular  type,  every  ice 
molecule  takes  its  place  upon  our  ponds  and  lakes  during 
the  frosts  of  winter.  To  use  the  language  of  an  American 
poet,  "  the  atoms  march  in  tune/'  moving  to  the  music  of 
law,  which  thus  renders  the  commonest  substance  in 
nature  a  miracle  of  beauty. 

It  is  the  function  of  science,  not  as  some  think  to  divest 
this  universe  of  its  wonder  and  mystery,  but,  as  in  the  case 
before  us,  to  point  out  the  wonder  and  the  mystery  of 
common  things.  Those  fern-like  forms,  which  on  a  frosty 
morning  overspread  your  window  panes,  illustrate  the 
action  of  the  same  force.  Breathe  upon  such  a  pane 
before  the  fires  are  lighted,  and  reduce  the  solid  crystalline 
film  to  the  liquid  condition;  then  watch  its  subsequent 
resolidification.  You  will  see  it  all  the  better  if  you  look 
at  it  through  a  common  magnifying  glass.  After  you  have 
ceased  breathing,  the  film,  abandoned  to  the  action  of  its 
own  forces,  appears  for  a  moment  to  be  alive.  Lines  of 
motion  run  through  it;  molecule  closes  with  molecule, 
until  finally  the  whole  film  passes  from  the  state  of  liquidity, 
through  this  state  of  motion,  to  its  final  crystalline 
repose. 

I  can  show  you  something  similar.  Over  a  piece  of  per- 
fectly clean  glass  I  pour  a  little  water  in  which  certain 
crystals  have  been  dissolved.  A  film  of  the  solution  clings 
to  the  glass.  By  means  of  a  microscope  and  a  lamp,  an 
image  of  the  plate  of  glass  is  thrown  upon  the  screen. 
The  beam  of  the  lamp,  besides  illuminating  the  glass,  also 
heats  it;  evaporation  sets  in,  and  at  a  certain  moment,  when 
the  solution  has  become  supersaturated,  splendid  branches 
of  crystal  shoot  out  over  the  screen.  A  dozen  square  feet 


392  FRAGMENTS  OF  SCIENCE. 

of  surface  are  now  covered  by  those  beautiful  forms.  With 
another  solution  we  obtain  crystalline  spears,  feathered 
right  and  left  by  other  spears.  From  distant  nuclei  in  the 
middle  of  the  field  of  view  the  spears  shoot  with  magical 
rapidity  in  all  directions.  The  film  of  water  on  a  window 
pane  on  a  frosty  morning  exhibits  effects  quite  as  wonder- 
ful as  these.  Latent  in  these  formless  solutions,  latent  in 
every  drop  of  water,  lies  this  marvelous  structural  power, 
which  only  requires  the  withdrawal  of  opposing  forces  to 
bring  it  into  action. 

The  clear  liquid  now  held  up  before  you  is  a  solution  of 
nitrate  of  silver — a  compound  of  silver  and  nitric  acid. 
When  an  electric  current  is  sent  through  this  liquid  the 
silver  is  severed  from  the  acid,  as  the  hydrogen  was  sepa- 
rated from  the  oxygen  in  a  former  experiment;  and  I  would 
ask  you  to  observe  how  the  metal  behaves  when  its  mole- 
cules are  thus  successively  set  free.  The  image  of  the  cell, 
and  of  the  two  wires  which  dip  into  the  liquid  of  the  cell, 
are  now  clearly  shown  upon  the  screen.  Let  us  close  the 
circuit,  and  send  the  current  through  the  liquid.  From 
one  of  the  wires  a  beautiful  silver  tree  commences  im- 
mediately to  sprout.  Branches  of  the  metal  are  thrown 
out,  and  umbrageous  foliage  loads  the  branches.  You 
have  here  a  growth,  apparently  as  wonderful  as  that  of 
any  vegetable,  perfected  in  a  minute  before  your  eyes. 
Substituting  for  the  nitrate  of  silver  acetate  of  lead, 
which  is  a  compound  of  lead  and  acetic  acid,  the  electric 
current  severs  the  lead  from  the  acid,  and  you  see  the 
metal  slowly  branching  into  exquisite  metallic  ferns,  the 
fronds  of  which,  as  they  become  too  heavy,  break  from 
their  roots  and  fall  to  the  bottom  of  the  celh 

These  experiments  show  that  the  common  matter  of 
our  earth — "  brute  matter,"  as  Dr.  Young,  in  his  "  Night 
Thoughts,"  is  pleased  to  call  it — when  its  atoms  and  mole- 
cules are  permitted  to  bring  their  forces  into  free  play, 
arranges  itself,  under  the  operation  of  these  forces,  into 
forms  which  rival  in  beauty  those  of  the  vegetable  world. 
And  what  is  the  vegetable  world  itself,  but  the  result  of 
the  complex  play  of  these  molecular  forces?  Here,  as 
elsewhere  throughout  nature,  if  matter  moves  it  is  force 
that  moves  it,  and  if  a  certain  structure,  vegetable  or 
mineral,  is  produced,  it  is  through  the  operation  of  the 
forces  exerted  between  the  atoms  and  molecules. 


MATTER  AND  FORCE.  393 

The  solid  matter  of  which  our  lead  and  silver  trees 
were  formed  was,  in  the  first  instance,  disguised  in  a  trans- 
parent liquid;  the  solid  matter  of  which  our  woods  and 
forests  are  composed  is  also,  for  the  most  part,  disguised  in 
a  transparent  gas,  which  is  mixed  in  small  quantities  with 
the  air  of  our  atmosphere.  This  gas  is  formed  by  the 
union  of  carbon  and  oxygen,  and  is  called  carbonic  acid 
gas.  The  carbonic  acid  of  the  air  being  subjected  to  an 
action  somewhat  analogous  to  that  of  the  electric  current 
in  the  case  of  our  lead  and  silver  solutions,  has  its  carbon 
liberated  and  deposited  as  woody  fiber.  The  watery  vapor 
of  the  air  is  subjected  to  similar  action;  its  hydrogen  is 
liberated  from  its  oxygen,  and  lies  down  side  by  side  with 
the  carbon  in  the  tissues  of  the  tree.  The  oxygen  in  both 
cases  is  permitted  to  wander  away  into  the  atmosphere. 
But  what  is  it  in  nature  that  plays  the  part  of  the  electric 
current  in  our  experiments,  tearing  asunder  the  locked 
atoms  of  carbon,  oxygen,  and  hydrogen?  The  rays  of  the 
sun.  The  leaves  of  plants  which  absorb  both  the  carbonic 
acid  and  the  aqueous  vapor  of  the  air,  answer  to  the  cells 
in  which  our  decompositions  took  place.  And  just  as  the 
molecular  attractions  of  the  silver  and  the  lead  found  ex- 
pression in  those  beautiful  branching  forms  seen  in  our 
experiments,  so  do  the  molecular  attractions  of  the  liberated 
carbon  and  hydrogen  find  expression  in  the  architecture  of 
grasses,  plants,  and  trees. 

In  the  fall  of  a  cataract  and  the  rush  of  the  wind  we 
have  examples  of  mechanical  power.  In  the  combinations 
of  chemistry  and  in  the  formation  of  crystals  and  vege- 
tables we  have  examples  of  molecular  power.  You  have 
learned  how  the  atoms  of  oxygen  and  hydrogen  rush  to- 
gether to  form  water.  I  have  not  thought  it  necessary  to 
dwell  upon  the  mighty  mechanical  energy  of  their  act  of 
combination;  but  it  may  be  said,  in  passing,  that  the 
clashing  together  of  1  Ib.  of  hydrogen  and  8  Ibs.  of  oxygen 
to  form  9  Ibs.  of  aqueous  vapor,  is  greater  than  the  shock 
of  a  weight  of  1,000  tons  falling  from  a  height  of  20  feet 
against  the  earth.  Now,  in  order  that  the  atoms  of  oxygen 
and  hydrogen  should  rise  by  their  mutual  attractions  to 
the  velocity  corresponding  to  this  enormous  mechanical 
effect,  a  certain  distance  must  exist  between  the  particles. 
It  is  in  rushing  over  this  that  the  velocity  is  attained. 


394  FRAGMENTS  OF  SCIENCE. 

This  idea  of  distance  between  the  attracting  atoms  is  of 
the  highest  importance  in  onr  conception  of  the  system  of 
the  world.  For  the  matter  of  the  world  may  be  classified 
under  two  distinct  heads:  atoms  and  molecules  which  have 
already  combined  and  thus  satisfied  their  mutual  attrac- 
tions, and  atoms  and  molecules  which  have  not  yet  com- 
bined, and  whose  mutual  attractions  are,  therefore,  un- 
satisfied. Now,  as  regards  motive  power,  we  are  entirely 
dependent  on  atoms  and  molecules  of  the  latter  kind. 
Their  attractions  can  produce  motion,  because  sufficient 
distance  intervenes  between  the  attracting  atoms,  and  it  is 
this  atomic  motion  that  we  utilize  in  our  machines.  Thus 
we  can  get  power  out  of  oxygen  and  hydrogen  by  the  act 
of  their  union;  but  once  they  are  combined,  and  once  the 
vibratory  motion  consequent  on  their  combinations  has 
been  expended,  no  further  power  can  be  got  out  of  their 
mutual  attraction.  As  dynamic  agents  they  are  dead. 
The  materials  of  the  earth's  crust  consist  for  the  most  part 
of  substances  whose  atoms  have  already  closed  in  chemical 
union — whose  mutual  attractions  are  satisfied.  Granite, 
for  instance,  is  a  widely  diffused  substance;  but  granite 
consists,  in  great  part,  of  silicon,  oxygen,  potassium,  cal- 
cium, and  aluminum,  whose  atoms  united  long  ago,  and 
are  therefore  dead.  Limestone  is  composed  of  carbon, 
oxygen,  and  a  metal  called  calcium,  the  atoms  of  which 
have  already  closed  in  chemical  union,  and  are  therefore 
finally  at  rest.  In  this  way  we  might  go  over  nearly  the 
whole  of  the  materials  of  the  earth's  crust,  and  satisfy  our- 
selves that  though  they  were  sources  of  power  in  ages  past, 
and  long  before  any  creature  appeared  on  the  earth  capable 
of  turning  their  power  to  account,  they  are  sources  of  power 
no  longer.  And  here  we  might  halt  for  a  moment  to 
remark  on  that  tendency,  so  prevalent  in  the  world,  to 
regard  everything  as  made  for  human  use.  Those  who 
entertain  this  notion,  hold,  I  think,  an  overweening  opin- 
ion of  their  own  importance  in  the  system  of  nature. 
Flowers  bloomed  before  men  saw  them,  and  the  quantity 
of  power  wasted  before  man  could  utilize  it  is  all  but  infi- 
nite compared  with  what  now  remains.  We  are  truly  heirs 
of  all  the  ages;  but  as  honest  men  it  behooves  us  to  learn 
the  extent  of  our  inheritance,  and  as  brave  ones  not  to 
whimper  if  it  should  prove  less  than  we  had  supposed. 
The  healthy  attitude  of  mind  with  reference  to  this  sub- 


MATTER  AND  FORCE.  395 

ject  is  that  of  the  poet,  who,  when  asked  whence  came  the 
rliodora,  joyfully  acknowledged  his  brotherhood  with  the 
flower: 

Why  thou  wert  there,  O  rival  of  the  rose! 

I  never  thought  to  ask,  I  never  knew, 

But  in  my  simple  ignorance  supposed 

The  selfsame  power  that  brought  me  there  brought  you.* 

A  few  exceptions  to  the  general  state  of  union  of  the 
molecules  of  the  earth's  crust — vast  in  relation  to  us,  but 
trivial  in  comparison  to  the  total  store  of  whicli  they  are  the 
residue — still  remain.  They  constitute  our  main  sources 
of  motive  power.  By  far  the  most  important  of  these 
are  our  beds  of  coal.  Distance  still  intervenes  between 
the  atoms  of  carbon  and  those  of  atmospheric  oxygen, 
across  which  the  atoms  may  be  urged  by  their  mutual 
attractions:  and  we  can  utilize  the  motion  thus  produced. 
Once  the  carbon  and  the  oxygen  have  rushed  together,  so 
as  to  form  carbonic  acid,  their  mutual  attractions  are  satis- 
fied; and,  while  they  continue  in  this  condition,  as  dynamic 
agents  they  are  dead.  Our  woods  and  forests  are  also 
sources  of  mechanical  energy,  because  they  have  the  power  of 
uniting  with  the  atmospheric  oxygen.  Passing  from  plants 
to  animals,  we  find  that  the  source  of  motive  power  just 
referred  to  is  also  the  source  of  muscular  power.  A  horse 
can  perform  work,  and  so  can  a  man;  but  this  work  is  at 
bottom  the  molecular  work  of  the  transmuted  food  and 
the  oxygen  of  the  air.  We  inhale  this  vital  gas,  and  bring 
it  into  sufficiently  close  proximity  with  the  carbon  and  the 
hydrogen  of  the  body.  These  unite  in  obedience  to  their 
mutual  attractions;  and  their  motion  toward  each  other, 
properly  turned  to  account  by  the  wonderful  mechanism  of 
the  body,  becomes  muscular  motion. 

One  fundamental  thought  pervades  all  these  statements: 
there  is  one  tap  root  from  which  they  all  spring.  This  is 
the  ancient  maxim  that  out  of  nothing  nothing  comes; 
that  neither  in  the  organic  world  nor  in  the  inorganic  is 
power  produced  without  the  expenditure  of  power;  that 
neither  in  the  plant  nor  in  the  animal  is  there  a  creation  of 
force  or  motion.  Trees  grow,  and  so  do  men  and  horses; 
and  here  we  have  new  power  incessantly  introduced  upon 
the  earth.  But  its  source,  as  I  have  already  stated,  is  the 

*  Emerson. 


396  FRAGMENTS  OF  SCIENCE. 

sun.  It  is  the  sun  that  separates  the  carbon  from  the 
oxygen  of  the  carbonic  acid,  and  thus  enables  them  to 
recombine.  Whether  they  recombine  in  the  furnace  of  the 
steam-engine  or  in  the  animal  body,  the  origin  of  the 
power  they  produce  is  the  same.  In  this  sense  we  are  all 
"  souls  of  fire  and  children  of  the  sun."  But,  as  remarked 
by  Helmholtz,  we  must  be  content  to  share  our  celestial 
pedigree  with  the  meanest  of  living  things. 

Some  estimable  persons,  here  present,  very  possibly 
shrink  from  accepting  these  statements;  they  may  be 
frightened  by  their  apparent  tendency  toward  what  is 
called  materialism — a  word  which,  to  many  minds  expresses 
something  very  dreadful.  But  it  ought  to  be  known  and 
avowed  that  the  physical  philosopher,  as  such,  must  be  a 
pure  materialist.  His  inquiries  deal  with  matter  and  force, 
and  with  them  alone.  And  whatever  be  the  forms  which 
matter  and  force  assume,  whether  in  the  organic  world  or 
the  inorganic,  whether  in  the  coal-beds  and  forests  of  the 
earth,  or  in  the  brains  and  muscles  of  men,  the  physical 
philosopher  will  make  good  his  right  to  investigate  them. 
It  is  perfectly  vain  to  attempt  to  stop  inquiry  in  this  direc- 
tion. Depend  upon  it,  if  a  chemist  by  bringing  the  proper 
materials  together,  in  a  retort  or  crucible,  could-  make  a 
baby,  he  would  do  it.  There  is  no  law,  moral  or  physical, 
forbidding  him  to  do  it.  At  the  present  moment  there  are, 
no  doubt,  persons  experimenting  on  the  possibility  of  pro- 
ducing what  we  call  life  out  of  inorganic  materials.  Let 
them  pursue  their  studies  in  peace;  it  is  only  by  such 
trials  that  they  will  learn  the  limits  of  their  own  powers 
and  the  operation  of  the  laws  of  matter  and  force. 

But  while  thus  making  the  largest  demand  for  freedom 
of  investigation — while  I  consider  science  to  be  alike  power- 
ful as  an  instrument  of  intellectual  culture  and  as  a  min- 
istrant  to  the  material  wants  of  men;  if  you  ask  me 
whether  it  has  solved,  or  is  likely  in  our  day  to  solve,  the 
problem  of  this  universe,  I  must  shake  my  head  in  doubt. 
You  remember  the  first  Napoleon's  question,  when  the 
savans  who  accompanied  him  to  Egypt  discussed  in  his 
presence  the  origin  of  the  universe,  and  solved  it  to  their 
own  apparent  satisfaction.  He  looked  aloft  to  the  starry 
heavens,  and  said,  "  It  is  all  very  well,  gentlemen;  but  who 
made  these?"  That  question  still  remains  unanswered, 
and  science  makes  no  attempt  to  answer  it.  As  far  as  I 


MATTER  AND  FORCE.  39? 

can  see,  there  is  no  quality  in  the  human  intellect  which  is 
fit  to  be  applied  to  the  solution  of  the  problem.  It  entirely 
transcends  us.  The  mind  of  man  may  be  compared  to  a 
musical  instrument  with  a  certain  range  of  notes,  beyond 
which  in  both  directions  we  have  an  infinitude  of  silence. 
The  phenomena  of  matter  and  force  lie  within  our  intel- 
lectual range,  and  as  far  as  they  reach  we  will  at  all  hazards 
push  our  inquiries.  But  behind,  and  above,  and  around 
all,  the  real  mystery  of  this  universe  lies  unsolved,  and,  as 
far  as  we  are  concerned,  is  incapable  of  solution.  Fashion 
this  mystery  as  you  will,  with  that  I  have  nothing  to  do. 
But  let  your  conception  of  it  not  be  an  unworthy  one. 
Invest  that  conception  with  your  highest  and  holiest 
thought,  but  be  careful  of  pretending  to  know  more  about 
it  than  is  given  to  man  to  know.  Be  careful,  above  all 
things,  of  professing  to  see  in  the  phenomena  of  the  ma- 
terial world  the  evidences  of  Divine  pleasure  or  displeasure. 
Doubt  those  who  would  deduce  from  the  fall  of  the  tower 
of  Siloarn  the  anger  of  the  Lord  against  those  who  were 
crushed.  Doubt  equally  those  who  pretend  to  see  in 
cholera,  cattle-plague,  and  bad  harvests,  evidences  of 
Divine  anger.  Doubt  those  spiritual  guides  who  in  Scot- 
land have  lately  propounded  the  monstrous  theory  that  the 
depreciation  of  railway  scrip  is  a  consequence  of  railway 
traveling  on  Sundays.  Let  them  not,  as  far  as  you  are 
concerned,  libel  the  system  of  nature  with  their  ignorant 
hypotheses.  Looking  from  the  solitudes  of  thought  into 
this  highest  of  questions,  and  seeing  the  puerile  attempts 
often  made  to  solve  it,  well  might  the  mightiest  of  living 
Scotchmen — that  strong  and  earnest  soul,  who  has  mad^ 
every  soul  of  like  nature  in  these  islands  his  debtor — well, 
I  say,  might  your  noble  old  Carlyle  scornfully  retort  on. 
such  interpreters  of  the  ways  of  God  to  men: 

The  Builder  of  this  universe  was  wise, 

He  formed  all  souls,  all  systems,  planets,  particles; 

The  plan  he  formed  his  worlds  and  JSons  by, 

Was — Heavens! — was  thy  small  nine-and-thirty  articles', 


398  FRAGMENTS  OF  SCIENCE. 

CHAPTER  XXVIII. 

SCIENTIFIC    MATERIALISM.*      1868. 

Here,  indeed,  we  arrive  at  the  barrier  which  needs  to  be  perpetually 
pointed  out;  alike  to  those  who  seek  materialistic  explanations  of 
mental  phenomena,  and  to  those  who  are  alarmed  lest  such  expla- 
nations may  be  found.  The  last  class  prove  by  their  fear,  almost  as 
much  as  the  first  prove  by  their  hope,  that  they  believe  Mind  may 
possibly  be  interpreted  in  terms  of  Matter;  whereas  many  whom  they 
vituperate  as  materialists  are  profoundly  convinced  that  there  is 
not  the  remotest  possibility  of  so  interpreting  them. — HERBERT 
SPENCER. 

THE  celebrated  Ficbte,  in  his  lectures  on  the  "Voca- 
tion of  the  Scholar,"  insisted  on  a  culture  which  should 
be  not  one-sided,  but  all-sided.  The  scholar's  intellect 
was  to  expand  spherically,  and  not  in  a  single  direction 
only.  In  one  direction,  however,  Fichte  required  that  the 
scholar  should  apply  himself  directly  to  nature,  become  a 
creator  of  knowledge,  and  thus  repay,  by  original  labors  of 
his  own,  the  immense  debt  he  owed  to  the  labors  of  others. 
It  was  these  which  enabled  him  to  supplement  the  knowledge 
derived  from  his  own  researches,  so  as  to  render  his  culture 
rounded  and  not  one-sided. 

As  regards  science,  Fichte's  idea  is  to  some  extent  illus- 
trated by  the  constitution  and  labors  of  the  British  Asso- 
ciation. We  have  here  a  body  of  men  engaged  in  the 
pursuit  of  Natural  Knowledge,  but  variously  engaged. 
While  sympathizing  with  each  of  its  departments,  and 
supplementing  his  culture  by  knowledge  drawn  from  all 
of  them,  each  student  among  us  selects  one  subject  for  the 
exercise  of  his  own  original  faculty — one  line,  along  which 
he  may  carry  the  light  of  his  private  intelligence  a  little 
way  into  the  darkness  by  which  all  knowledge  is  surrounded. 
Thus,  the  geologist  deals  with  the  rocks;  the  biologist 
with  the  conditions  and  phenomena  of  life;  the  astronomer 
with  stellar  masses  and  motions;  the  mathematician  with 
the  relations  of  space  and  number;  the  chemist  pursues 
his  atoms;  while  the  physical  investigator  has  his  own 
large  field  in  optical,  thermal,  electrical,  acoustical,  and 
other  phenomena.  The  British  Association  then,  as  a 

*  President's  Address  to  the  Mathematical  and  Physical  Section 
of  the  British  Association  at  Norwich, 


SCIENTIFIC  MATERIALISM.  309 

whole,  faces  physical  nature  on  all  sides,  and  pushes  knowl- 
edge centrifugally  outward,  the  sum  of  its  labors  con- 
stituting what  Fichte  might  call  the  sphere  of  natural 
knowledge.  In  the  meetings  of  the  association  it  is  found 
necessary  to  resolve  this  sphere  into  its  component  parts, 
which  take  concrete  form  under  the  respective  letters  of 
our  Sections. 

Mathematics  and  Physics  have  been  long  accustomed  to 
coalesce,  and  here  they  form  a  single  section.  No  matter 
how  subtle  a  natural  phenomenon  may  be,  whether  we 
observe  it  in  the  region  of  sense,  or  follow  it  into  that  of 
imagination,  it  is  in  the  long  run  reducible  to  mechanical 
laws.  But  the  mechanical  data  once  guessed  or  given, 
mathematics  are  all-powerful  as  an  instrument  of  deduction. 
The  command  of  Geometry  over  the  relations  of  space,  and 
the  far-reaching  power  which  Analysis  confers,  are  Dotent 
both  as  means  of  physical  discovery,  and  of  reaping  the 
entire  fruits  of  discovery.  Indeed,  without  mathematics, 
expressed  or  implied,  our  knowledge  of  physical  science 
would  be  both  friable  and  incomplete. 

Side  by  side  with  the  mathematical  method  we  have  the 
method  of  experiment.  Here  from  a  starting-point  fur- 
nished by  his  own  researchesvor  those  of  others,  the  inves- 
tigator proceeds  by  combining  intuition  and  verification. 
He  ponders  the  knowledge  he  possesses,  and  tries  to  push 
it  further;  he  guesses,  and  checks  his  guess;  he  conjectures, 
and  confirms  or  explodes  his  conjecture.  These  guesses 
and  conjectures  are  by  no  means  leaps  in  the  dark;  for 
knowledge  once  gained  casts  a  faint  light  beyond  its  own 
immediate  boundaries.  There  is  no  discovery  so  limited  as 
not  to  illuminate  something  beyond  itself.  The  force  of 
intellectual  penetration  into  this  penumbral  region  which 
surrounds  actual  knowledge  is  not,  as  some  seem  to  think, 
dependent  upon  method,  but  upon  the  genius  of  the  inves- 
tigator. There  is,  however,  no  genius  so  gifted  as  not  to 
need  control  and  verification.  The  profoundest  rninds 
know  best  that  nature's  ways  are  not  at  all  times  their 
ways,  and  that  the  brightest  flashes  in  the  world  of  thought 
are  incomplete  until  they  have  been  proved  to  have  their 
counterparts  in  the  world  of  fact.  Thus  the  vocation  of  the 
true  experimentalist  may  be  defined  as  the  continued  exer- 
cise of  spiritual  insight,  audits  incessant  correction  and 
realization.  His  experiments  constitute  a  body,  of  which 
his  purified  intuitions  are,  as  it  were,  the  soul, 


400  FRAGMENTS  OF  SCIENCE. 

Partly  through  mathematical  and  partly  through  experi- 
mental research,  physical  science  has,  of  late  years, 
assumed  a  momentous  position  in  the  world.  Both  in  a 
material  and  in  an  intellectual  point  of  view  it  has  pro- 
duced, and  it  is  destined  to  produce,  immense  changes — 
vast  social  ameliorations,  and  vast  alterations  in  the  popular 
conception  of  the  origin,  rule,  and  governance  of  natural 
tilings.  By  science,  in  the  physical  world,  miracles  are 
wrought,  while  philosophy  is  forsaking  its  aticient  meta- 
physical channels,  and  pursuing  others  which  have  been 
opened,  or  indicated  by  scientific  research.  This  must 
become  more  and  more  the  case  as  philosophical  writers 
become  more  deeply  imbued  with  the  methods  of  science, 
better  acquainted  with  the  facts  which  scientific  men  have 
established,  and  with  the  great  theories  which  they  have 
elaborated. 

If  you  look  at  the  face  of  a  watch,  you  see  the  hour  and 
minute-hands,  and  possibly  also  a  second-hand,  moving 
over  the  graduated  dial.  Why  do  these  hands  move?  and 
why  are  their  relative  motions  such  as  they  are  observed  to 
be?  These  questions  cannot  be  answered  without  opening 
the  watch,  mastering  its  various  parts,  and  ascertaining 
their  relationship  to  each  other.  When  this  is  done,  we 
find  that  the  observed  motion  of  the  hands  follows  of 
necessity  from  the  inner  mechanism  of  the  watch  when 
acted  upon  by  the  force  invested  in  the  spring.  The 
motion  of  the  hands  may  be  called  a  phenomenon  of  art, 
but  the  case  is  similar  with  the  phenomena  of  nature. 
These  also  have  their  inner  mechanism  and  their  store  of 
force  to  set  that  mechanism  going.  The  ultimate  problem 
of  physical  science  is  to  reveal  this  mechanism,  to  discern 
this  store,  and  to  show  that  from  the  combined  action  of 
both,  the  phenomena  of  which  they  constitute  the  basis, 
must,  of  necessity,  flow. 

I  thought  an  attempt  to  give  you  even  a  brief  and  sketchy 
illustration  of  the  manner  in  which  scientific  thinkers 
regard  this  problem  would  not  be  uninteresting  to  you  on 
the  present  occasion;  more  especially  as  it  will  give  me 
occasion  to  say  a  word  or  two  on  the  tendencies  and  limits 
of  modern  science;  to  point  out  the  region  which  men  of 
science  claim  as  their  own,  and  where  it  is  futile  to  oppose 
their  advance;  and  also  to  define,  if  possible,  the  bourne 
between  this  and  that  other  region,  to  which  the  question- 


SCIENTIFIC  MA  TERIA  LISM.  401 

ings  and  yearnings  of  the  scientific  intellect  are  directed 
in  vain. 

But  here  your  tolerance  will  be  needed.  It  was  the 
American  Emerson,  I  think,  who  said  that  it  is  hardly 
possible  to  state  any  truth  strongly,  without  apparent 
injustice  to  some  other  truth.  Truth  is  often  of  a  dual 
character,  taking  the  form  of  a  magnet  with  two  poles; 
and  many  of  the  differences  which  agitate  the  thinking 
part  of  mankind  are  to  be  traced  to  the  exclusiveness  with 
which  partisan  reasoners  dwell  upon  one  half  of  the  dual- 
ity, in  forgetfulness  of  the  other.  The  proper  course 
appears  to  be  to  state  both  halves  strongly,  and  allow  each 
its  fair  share  in  the  formation  of  the  resultant  conviction. 
But  this  waiting  for  the  statement  of  the  two  sides  of  a 
question  implies  patience.  It  implies  a  resolution  to  sup- 
press indignation,  if  the  statement  of  the  one  half  should 
clash  with  our  convictions;  and  to  repress  equally  undue 
elation,  if  the  half-statement  should  happen  to  chime  in 
with  our  views.  It  implies  a  determination  to  wait  calmly 
for  the  statement  of  the  whole,  before  we  pronounce 
judgment  in  the  form  of  either  acquiescence  or  dissent. 

This  premised,  and  I  trust  accepted,  let  us  enter  upon 
our  task.  There  have  been  writers  who  affirmed  that  the 
pyramids  of  Egypt  were  natural  productions;  and  in  his 
early  youth  Alexander  von  Humboldt  wrote  a  learned  essay 
with  the  express  object  of  refuting  this  notion.  We  now 
regard  the  pyramids  as  the  work  of  men's  hands,  aided 
probably  by  machinery  of  which  no  record  remains.  We 
picture  to  ourselves  the  swarming  workers  toiling  at  those 
vast  erections,  lifting  the  inert  stones,  and,  guided  by  the 
volition,  the  skill,  and  possibly  at  times  by  the  whip  of  the 
architect,  placing  them  in  their  proper  positions.  The 
blocks,  in  this  case,  were  moved  and  posited  by  a  power 
external  to  themselves,  and  the  final  form  of  the  pyramid 
expressed  the  thought  of  its  human  builder. 

Let  us  pass  from  this  illustration  of  constructive  power 
to  another  of  a  different  kind.  When  a  solution  of  common 
salt  is  slowly  evaporated,  the  water  which  holds  the  salt  in 
solution  disappears,  but  the  salt  itself  remains  behind.  At 
a  certain  stage  of  concentration  the  salt  can  no  longer  retain 
the  liquid  form;  its  particles,  or  molecules,  as  they  are 
called,  begin  to  deposit  themselves  as  minute  solids — so 
minute,  indeed,  as  to  defy  all  microscopic  power.  As  evap- 


402  FRAGMENTS  OF  SCIENCE. 

oration  continues,  solidification  goes  on,  and  we  finally 
obtain  through  the  clustering  together  of  innumerable 
molecules,  a  finite  crystalline  mass  of  a  definite  form. 
What  is  this  form?  It  sometimes  seems  a  mimicry  of  the 
architecture  of  Egypt.  We  have  little  pyramids  built  by 
the  salt,  terrace  above  terrace  from  base  to  apex,  forming  a 
series^of  steps  resembling  those  up  which  the  traveler  in 
Egypt  is  dragged  by  his  guides.  The  human  mind  is  as 
little  disposed  to  look  without  questioning  at  these  pyra- 
midal salt-crystals,  as  to  look  at  the  pyramids  of  Egypt, 
without  inquiring  whence  they  came.  How,  then,  are 
those  salt-pyramids  built  up? 

Guided  by  analogy,  you  may,  if  you  like,  suppose  that, 
swarming  among  the  constituent  molecules  of  the  salt, 
there  is  an  invisible  population,  controlled  and  coerced  by 
some  invisible  master,  placing  the  atomic  blocks  in  their 
positions.  This,  however,  is  not  the  scientific  idea,  nor  do 
I  think  your  good  sense  will  accept  it  as  a  likely  one.  The 
scientific  idea  is,  that  the  molecules  act  upon  each  other 
without  the  intervention  of  slave  labor;  that  they  attract 
each  other,  and  repel  each  other,  at  certain  definite  points, 
or  poles,  and  in  certain  definite  directions;  and  that  the 
pyramidal  form  is  the  result  of  this  play  of  attraction  and 
repulsion.  While,  then,  the  blocks  of  Egypt  were  laid 
down  by  a  power  external  to  themselves,  these  molecular 
blocks  of  salt  are  self-posited,  being  fixed  in  their  places  by 
the  inherent  forces  with  which  they  act  upon  each  other. 

I  take  common  salt  as  an  illustration,  because  it  is  so 
familiar  to  us  all;  but  any  othercrystalline  substance  would 
answer  my  purpose  equally  well.  Everywhere,  in  fact, 
throughout  inorganic  nature,  we  have  this  formative  power, 
as  Fichte  would  call  it — this  structural  energy  ready  to 
come  into  play,  and  build  the  ultimate  particles  of  matter 
into  definite  shapes.  The  ice  of  our  winters,  and  of  our 
polar  regions,  is  its  handiwork,  and  so  also  are  the  quartz, 
feldspar,  and  mica  of  our  rocks.  Our  chalk-beds  are  for  the 
most  part  composed  of  minute  shells,  which  are  also  the 
product  of  structural  energy;  but  behind  the  shell,  as  a 
whole,  lies  a  more  remote  and  subtle  formative  act.  These 
shells  are  built  up  of  little  crystals  of  calc-spar,  and,  to 
form  these  crystals,  the  structural  force  had  to  deal  with 
the  intangible  molecules  of  carbonate  of  lime.  This  ten- 
dency on  the  part  of  matter  to  organize  itself,  to  grow  into 


SCIENTIFIC  MATERIALISM.  403 

shape,  to  assume  definite  forms  in  obedience  to  the 
definite  action  of  force,  is,  as  I  have  said,  all-pervading. 
It  is  in  the  ground  on  which  you  tread,  in  the  water  you 
drink,  in  the  air  you  breathe.  Incipient  life,  as  it  were, 
manifests  itself  throughout  the  whole  of  what  we  call  inor- 
ganic nature. 

The  forms  of  the  minerals  resulting  from  this  play  of 
polar  forces  are  various,  and  exhibit  different  degrees  of 
complexity.  Men  of  science  avail  themselves  of  all  possible 
means  of  exploring  their  molecular  architecture.  For  this 
purpose  they  employ  in  turn,  as  agents  of  exploration, 
light,  heat,  magnetism,  electricity,  and  sound.  Polarized 
light  is  especially  useful  and  powerful  here.  A  beam  of 
such  light,  when  sent  in  among  the  molecules  of  a  crystal, 
is  acted  on  by  them,  and  from  this  action  we  infer  with 
more  or  less  clearness  the  manner  in  which  the  molecules 
are  arranged.  That  differences,  for  example,  exist  between 
the  inner  structure  of  rocksaltand  that  of  crystallized  sugar 
or  sugar-candy,  is  thus  strikingly  revealed.  These  actions 
often  display  themselves  in  chromatic  phenomena  of  great 
splendor,  the  play  of  molecular  force  being  so  regulated 
as  to  cause  the  removal  of  some  of  the  colored  constituents 
of  white  light,  while  others  are  left  with  increased  intensity 
behind. 

And  now  let  us  pass  from  what  we  are  accustomed  to 
regard  as  a  dead  mineral,  to  a  living  grain  of  corn.  When 
this  is  examined  by  polarized  light,  chromatic  phenomena 
similar  to  those  noticed  in  crystals  are  observed.  And 
why?  Because  the  architecture  of  the  grain  resembles  that 
of  the  crystal.  In  the  grain  also  the  molecules  are  set  in 
definite  positions,  and  in  accordance  with  their  arrange- 
ment they  act  upon  the  light.  But  what  has  built  together 
the  molecules  of  the  corn?  Regarding  crystalline  archi- 
tecture, I  have  already  said  that  you  may,  if  you  please, 
consider  the  atoms  and  molecules  to  be  placed  in  position 
by  a  Power  external  to  themselves.  The  same  hypothesis 
is  open  to  you  now.  But  if  in  the  case  of  crystals  you  have 
rejected  this  notion  of  an  external  architect,  1  think  you 
are  bound  to  reject  it  in  the  case  of  the  grain,  and  to  con- 
clude that  the  molecules  of  the  corn,  also,  are  posited  by 
the  forces  with  which  they  act  upon  each  other.  It  would 
be  poor  philosophy  to  invoke  an  external  agent  in  the  one 
case,  and  to  reject  it  in  the  other. 


404  FRAGMENTS  OF  SCIENCE. 

Instead  of  cutting  our  grain  of  corn  into  slices  and  sub- 
jecting it  to  the  action  of  polarized  light,  let  us  place  it  in 
the  earth,  and  subject  it  to  a  certain  degree  of  warmth.  In 
other  words,  let  the  molecules,  both  of  the  corn  and  of  the 
surrounding  earth,  be  kept  in  that  state  of  agitation  which 
we  call  heat.  Under  these  circumstances,  the  grain  and 
the  substances  which  surround  it  interact,  and  a  definite 
molecular  architecture  is  the  result.  A  bud  is  formed; 
this  bud  reaches  the  surface,  where  it  is  exposed  to  the 
sun's  rays,  which  are  also  to  be  regarded  as  a  kind  of 
vibratory  motion.  And  as  the  motion  of  common  heat, 
with  which  the  grain  and  the  substances  surrounding  it 
were  first  endowed,  enabled  the  grain  and  these  substances 
to  exercise  their  mutual  attractions  and  repulsions,  and 
thus  to  coalesce  in  definite  forms,  so  the  specific  motion  of 
the  sun's  rays  now  enables  the  green  bud  to  feed  upon  the 
carbonic  acid  and  the  aqueous  vapor  of  the  air.  The  bud 
appropriates  those  constituents  of  both  for  which  it  has 
an  elective  attraction,  and  permits  the  other  constituent 
to  return  to  the  atmosphere.  Thus  the  architecture  is 
carried  on.  Forces  are  active  at  the  root,  forces  are  active 
in  the  blade,  the  matter  of  the  air  and  the  matter  of  the 
atmosphere  are  drawn  upon,  and  the  plant  augments  in 
size.  We  have  in  succession  the  stalk,  the  ear,  the  full  corn 
in  the  ear;  the  cycle  of  molecular  action  being  completed 
by  the  production  of  grains,  similar  to  that  with  which  the 
process  began. 

Now  there  is  nothing  in  this  process  which  necessarily 
eludes  the  conceptive  or  imagining  power  of  the  human 
mind.  An  intellect  the  same  in  kind  as  our  own  would,  if 
only  sufficiently  expanded,  be  able  to  follow  the  whole 
process  from  beginning  to  end.  It  would  see  every  mole- 
cule placed  in  its  position  by  the  specific  attractions  and 
repulsions  exerted  between  it  and  other  molecules,  the 
whole  process,  and  its  consummation,  being  an  instance  of 
the  play  of  molecular  force.  Given  the  grain  and  its  en- 
vironment, with  their  respective  forces,  the  purely  human 
intellect  might,  if  sufficiently  expanded,  trace  out  a  priori 
every  step  of  the  process  of  growth,  and,  by  the  application 
of  purely  mechanical  principles,  demonstrate  that  the  cycle 
must  end,  as  it  is  seen  to  end,  in  the  reproduction  of  forms 
like  that  with  which  it  began.  A  necessity  rules  here, 
similar  to  that  which  rules  the  planets  in  their  circuits 
round  the  sun. 


SCIENTIFIC  MATERIALISM.  405 

You  will  notice  that  I  am  stating  the  truth  strongly,  as 
at  the  beginning  we  agreed  it  should  be  stated.  But  I 
must  go  still  further,  and  affirm  that  in  the  eye  of  science 
the  animal  body  is  just  as  much  the  product  of  molecular 
force  as  the  chalk  and  the  ear  of  corn,  or  as  the  crystal  of 
salt  or  sugar.  Many  of  the  parts  of  the  body  are  obviously 
mechanical.  Take  the  human  heart,  for  example,  with  its 
system  of  valves,  or  take  the  exquisite  mechanism  of  the 
eye  or  hand.  Animal  heat,  moreover,  is  the  same  in  kind 
as  the  heat  of  a  fire,  being  produced  by  the  same  chemical 
process.  Animal  motion,  too,  is  as  certainly  derived  from 
the  food  of  the  animal,  as  the  motion  of  Trevethyck's 
walking-engine  from  the  fuel  in  its  furnace.  As  regards 
matter,  the  animal  body  creates  nothing;  as  regards  force, 
it  creates  nothing.  Which  of  you  by  taking  thought  can 
add  one  cubit  to  his  stature?  All  that  has  been  said,  then, 
regarding  the  plant,  may  be  restated  with  regard  to  the 
animal.  Every  particle  that  enters  into  the  composition 
of  a  nerve,  a  muscle,  or  a  bone  has  been  placed  in  its  posi- 
tion by  molecular  force.  And  unless  the  existence  of  law 
in  these  matters  be  denied,  and  the  element  of  caprice  in- 
troduced, we  must  conclude  that,  given  the  relation  of  any 
molecule  of  the  body  to  its  environment,  its  position  in  the 
body  might  be  determined  mathematically.  Our  difficulty 
is  not  with  the  quality  of  the  problem,  but  with  its  com* 
plexiiy;  and  this  difficulty  might  be  met  by  the  simple 
expansion  of  the  faculties  we  now  possess.  Given  this 
expansion,  with  the  necessary  molecular  data,  and  the  chick 
might  be  deduced  as  rigorously  and  as  logically  from  the 
egg,  as  the  existence  of  Neptune  from  the  disturbances  of 
Uranus,  or  as  conical  refraction  from  the  undulatory  theory 
of  light. 

You  see  I  am  not  mincing  matters,  but  avowing  nakedly 
what  many  scientific  thinkers  more  or  less  distinctly  believe. 
The  formation  of  a  crystal,  a  plant,  or  an  animal,  is,  in 
their  eyes,  a  purely  mechanical  problem,  which  differs  from 
the  problems  of  ordinary  mechanics,  in  the  smailness  of 
the  masses,  and  the  complexity  of  the  processes  involved. 
Here  you  have  one  half  of  our  dual  truth;  let  us  now 
glance  at  the  other  half.  Associated  with  this  wonderful 
mechanism  of  the  animal  body  we  have  phenomena  no  less 
certain  than  those  of  physics,  but  between  which  and  the 
mechanism  we  discern  no  necessary  connection,,  A  man, 


406  FRAGMENTS  OF  SCIENCE. 

for  example,  can  say  "  I  feel,"  "I  think,"  "  I  love;"  but 
how  does  consciousness  infuse  itself  into  the  problem? 
The  human  brain  is  said  to  be  the  organ  of  thought  and 
feeling:  when  we  are  hurt,  the  brain  feels  it;  when  we  pon- 
der, or  when  our  passions  or  affections  are  excited,  it  is 
through  the  instrumentality  of  the  brain.  Let  us  endeavor 
to  be  a  little  more  precise  here.  I  hardly  imagine  there 
exists  a  profound  scientific  thinker,  who  has  reflected  upon 
the  subject,  unwilling  to  admit  the  extreme  probability  of 
the  hypothesis,  that  for  every  fact  of  consciousness, 
whether  in  the  domain  of  sense,  thought,  or  emotion,  a 
definite  molecular  condition,  of  motion  or  structure,  is  set 
up  in  the  brain;  or  who  would  be  disposed  even  to  deny 
that  if  the  motion,  or  structure,  be  induced  by  internal 
causes  instead  of  external,  the  effect  on  consciousness  will 
be  the  same?  Let  any  nerve,  for  example,  be  thrown  by 
morbid  action  into  the  precise  state  of  motion  which  would 
be  communicated  to  it  by  the  pulses  of  a  heated  body, 
surely  that  nerve  will  declare  itself  hot — the  mind  will 
accept  the  subjective  intimation  exactly  as  if  it  were  ob- 
jective. The  retina  may  be  excited  by  purely  mechanical 
means.  A  blow  on  the  eye  causes  a  luminous  flash,  and 
the  mere  pressure  of  the  finger  on  the  external  ball  produces 
a  star  of  light,  which  Newton  compared  to  the  circles  on 
a  peacock's  tail.  Disease  makes  people  see  visions  and 
dream  dreams;  but,  in  all  such  cases,  could  we  examine 
the  organs  implicated,  we  should,  on  philosophical  grounds, 
expect  to  find  them  in  that  precise  molecular  condition 
which  the  real  objects,  if  present,  would  superinduce. 

The  relation  of  physics  to  consciousness  being  thus  in- 
variable, it  follows  that,  given  the  state  of  the  brain,  the 
corresponding  thought  or  feeling  might  be  inferred:  or, 
given  the  thought  or  feeling,  the  corresponding  state  of 
the  brain  might  be  inferred.  But  how  inferred?  It  would 
be  at  bottom  not  a  case  of  logical  inference  at  all,  but  of 
empirical  association.  You  may  reply,  that  many  of  the 
inferences  of  science  are  of  this  character — the  inference, 
for  example,  that  an  electric  current,  of  a  given  direction, 
will  deflect  a  magnetic  needle  in  a  definite  way.  But  the 
cases  differ  in  this,  that  the  passage  from  the  current  to 
the  needle,  if  not  demonstrable,  is  conceivable,  aud  that 
we  entertain  no  doubt  as  to  the  final  mechanical  solution 
pf  the  problem.  But  the  passage  from  the  physics  of  the 


SCIENTIFIC  MATERIALISM.  40? 

brain  to  the  corresponding  facts  of  consciousness  is  incon- 
ceivable as  a  result  of  mechanics.  Granted  that  a  definite 
thought,  and  a  definite  molecular  action  in  the  brain, 
occur  simultaneously;  we  do  not  possess  the  intellectual 
organ,  nor  apparently  any  rudiment  of  the  organ,  which 
would  enable  us  to  pass,  by  a  process  of  reasoning,  from 
the  one  to  the  other.  They  appear  together,  but  we  do 
not  know  why.  Were  our  minds  and  senses  so  expanded, 
strengthened,  and  illuminated,  as  to  enable  us  to  see  and 
feel  the  very  molecules  of  the  brain;  were  we  capable  of 
following  all  their  motions,  all  their  groupings,  all  their 
electric  discharges,  if  such  there  be;  and  were  we  inti- 
mately acquainted  with  the  correspond  ing  states  of  thought 
and  feeling,  we  should  be  as  far  as  ever  from  the  solution 
of  the  problem,  "  How  are  these  physical  processes  con- 
nected with  the  facts  of  consciousness?"  The  chasm 
between  the  two  classes  of  phenomena  would  still  remain 
intellectually  impassable.  Let  the  consciousness  of  love, 
for  example,  be  associated  with  a  right-handed  spiral 
motion  of  the  molecules  of  the  brain,  and  the  consciousness 
of  hate  with  a  left-handed  spiral  motion.  We  should  then 
know,  when  we  love,  that  the  motion  is  in  one  direction, 
and,  when  we  hate,  that  the  motion  is  in  the  other;  but 
the  "  WHY?"  would  remain  as  unanswerable  as  before. 

In  affirming  that  the  growth  of  the  body  is  mechanical, 
and  that  thought,  as  exercised  by  us,  has  its  correlative  in 
the  physics  of  the  brain,  I  think  the  position  of  the 
"  Materialist"  is  stated,  as  far  as  that  position  is  a  tenable 
one.  I  think  the  materialist  will  be  able  finally  to  main- 
tain this  position  against  all  attacks;  but  I  do  not  think, 
in  the  present  condition  of  the  human  mind,  that  he  can 
pass  beyond  this  position.  I  do  not  think  he  is  entitled  to 
say  that  his  molecular  groupings,  and  motions,  explain 
everything.  In  reality  they  explain  nothing.  The  utmost 
he  can  affirm  is  the  association  of  two  classes  of  phenomena, 
of  whose  real  bond  of  union  he  is  in  absolute  ignorance. 
The  problem  of  the  connection  of  body  and  soul  is  as 
insoluble,  in  its  modern  form,  as  it  was  in  the  pre-scieutific 
ages.  Phosphorus  is  known  to  enter  into  the  composition 
of  the  human  brain,  and  a  trenchant  German  writer  has 
exclaimed,  "Oline  Phosphor,  kein  Gedanke!"  That  may 
or  may  not  be  the  case;  but  even  if  we  knew  it  to  be  the 
case,  the  knowledge  would  not  lighten  our  darkness.  Oil 


408  FRAGMENTS  OF  SCIENCE. 

both  sides  of  the  zone  here  assigned  to  the  materialist  he 
is  equally  helpless.  If  you  ask  hirn  whence  is  this  "  Matter  " 
of  which  we  have  been  discoursing — who  or  what  divided 
it  into  molecules,  who  or  what  impressed  upon  them  this 
necessity  of  running  into  organic  forms — he  has  no  answer. 
Science  is  mute  in  reply  to  these  questions.  But  if  the 
materialist  is  confounded  and  science  rendered  dumb,  who 
else  is  prepared  with  a  solution?  To  whom  has  this  arm 
of  the  Lord  been  revealed?  Let  us  lower  our  heads,  and 
acknowledge  our  ignorance,  priest  and  philosopher,  one 
and  all. 

Perhaps  the  mystery  may  resolve  itself  into  knowledge 
at  some  future  day.  The  process  of  things  upon  this  earth 
has  been  one  of  amelioration.  It  is  a  long  way  from  the 
Iguanodon  and  his  contemporaries,  to  the  President  and 
Members  of  the  British  Association.  And  whether  we 
regard  the  improvement  from  the  scientific  or  from  the 
theological  point  of  view — as  the  result  of  progressive 
development,  or  of  successive  exhibitions  of  creative  energy 
— neither  view  entitles  us  to  assume  that  man's  present 
faculties  end  the  series,  that  the  process  of  amelioration 
ends  with  him.  A  time  may  therefore  come  when  this 
ultra-scientific  region,  by  which  we  are  now  enfolded, 
may  offer  itself  to  terrestrial,  if  not  to  human,  investigation. 
Two-thirds  of  the  rays  emitted  by  the  sun  fail  to  arouse 
the  sense  of  vision.  The  rays  exist,  but  the  visual  organ 
requisite  for  their  translation  into  light  does  not  exist. 
And  so  from  this  region  of  darkness  and  mystery  which 
surrounds  us,  rays  may  now  be  darting,  which  require  but 
the  development  of  the  proper  intellectual  organs  to  trans- 
late them  into  knowledge  as  far  surpassing  ours  as  ours 
surpasses  that  of  the  wallowing  reptiles  which  once  held 
possession  of  this  planet.  Meanwhile  the  mystery  is  not 
without  its  uses.  It  certainly  may  be  made  a  power  in  the 
human  soul;  but  it  is  a  power  which  has  feeling,  not 
knowledge,  for  its  base.  It  may  be,  will  be,  and  I  hope  is 
turned  to  account,  both  in  steadying  and  strengthening  the 
intellect,  and  in  rescuing  man  from  that  littleness  to 
which,  in  the  struggle  for  existence,  or  for  precedence  in 
the  world,  he  is  continually  prone. 


SCIENTIFIC  MATERIALISM.  409 

Musings  on  the  Matterhorn,  July  27,  1868. 

Hacked  and  hurt  by  time,  the  aspect  of  the  mountain 
from  its  higher  crags  saddened  me.  Hitherto  the  impres- 
sion it  made  was  that  of  savage  strength;  here  we  had 
inexorable  decay.  But  this  notion  of  decay  implied  a 
reference  to  a  period  when  the  Matterhorn  was  in  the 
full  strength  of  moimtainhood.  Thought  naturally  ran 
back  to  its  remoter  origin  and  sculpture.  Nor  did  thought 
halt  there,  but  wandered  on  through  molten  worlds  to  that 
nebulous  haze  which  philosophers  have  regarded,  and  with 
good  reason,  as  the  proximate  source  of  all  material  things. 
I  tried  to  look  at  this  universal  cloud,  containing  within 
itself  the  prediction  of  all  that  has  since  occurred;  I  tried 
to  imagine  it  as  the  seat  of  those  forces  whose  action  was  to 
issue  in  solar  and  stellar  systems,  and  all  that  they  involve. 
Did  that  formless  fog  contain  potentially  the  sadness  with 
which  I  regarded  the  Matterhorn?  Did  the  thought  which 
now  ran  back  to  it  simply  return  to  its  primeval  home? 
If  so,  had  we  not  better  recast  our  definitions  of  matter 
and  force?  for,  if  life  and  thought  be  the  very  flower  of 
both,  any  definition  which  omits  life  and  thought  must  be 
inadequate,  if  not  untrue.  Are  questions  like  these  war- 
ranted? Why  not?  If  the  final  goal  of  man  has  not  been 
yet  attained;  if  his  development  has  not  been  yet  arrested, 
who  can  say  that  such  yearnings  and  questionings  are  not 
necessary  to  the  opening  of  a  finer  vision,  to  the  budding 
and  the  growth  of  diviner  powers?  When  I  look  at  the 
heavens  and  the  earth,  at  my  own  body,  at  my  strength 
and  weakness,  even  at  these  ponderings,  and  ask  myself,  Is 
there  no  being  or  thing  in  the  universe  that  knows  more 
about  these  matters  than  I  do;  what  is  my  answer?  Sup- 
posing our  theologic  schemes  of  creation,  condemnation, 
and  redemption  to  be  dissipated;  and  the  warmth  of 
denial  which  they  excite,  and  which,  as  a  motive  force,  can 
match  the  warmth  of  affirmation,  dissipated  at  the  same 
time;  would  the  undeflected  human  mind  return  to  the 
meridian  of  absolute  neutrality  as  regards  these  ultra- 
physical  questions?  Is  such  a  position  one  of  stable  equili- 
brium? The  channels  of  thought  being  already  formed, 
such  are  the  questions,  without  replies,  which  could  run 
athwart  consciousness  during  a  ten  minutes'  halt  upon  the 
weathered  crest  of  the  Matterhorn. 


410  FRAGMENTS  OF  SCIENCE. 

CHAPTER  XXIX. 

AN   ADDKESS  TO   STUDENTS.* 

Self-reverence,  self-knowledge,  self  control, 
These  three  alone  lead  life  to  sovereign  power, 
Yet  not  for  power  (power  of  herself 
Would  come  uncalled  for),  but  to  live  by  law, 
Acting  the  law  we  live  by  without  fear; 
And,  because  right  is  right,  to  follow  right 
Were  wisdom  in  the  scorn  of  consequence. 

TENNYSON. 

THERE  is  an  idea  regarding  the  nature  of  man  which 
modern  philosophy  1ms  sought,  and  is  still  seeking,  to  raise 
into  clearness;  the  idea,  namely,  of  secular  growth.  Man 
is  not  a  thing  of  yesterday;  nor  do  I  imagine  that  the 
slightest  controversial  tinge  is  imparted  into  this  address 
when  I  say  that  he  is  not  a  thing  of  six  thousand  years 
ago.  Whether  he  carne  originally  from  stocks  or  stones, 
from  nebulous  gas  or  solar  fire,  I  know  not;  if  he  had  any 
such  origin  the  process  of  his  transformation  is  as  inscru- 
table to  you  and  me  as  that  of  the  grand  old  legend,  accord- 
ing to  which  "the  Lord  G-od  formed  man  of  the  dust  of 
the  ground,  and  breathed  into  his  nostrils  the  breath  of 
life;  and  man  became  a  livingsoul."  But  however  obscure 
man's  origin  may  be,  his  growth  is  not  to  be  denied.  Hero 
a  little  and  there  a  little  added  through  the  ages  have 
slowly  transformed  him  from  what  he  was  into  what  he  is. 
The  doctrine  has  been  held  that  the  mind  of  the  child  is 
like  a  sheet  of  white  paper,  on  which  by  education  we  can 
write  what  characters  we  please.  This  doctrine  assuredly 
needs  qualification  and  correction.  In  physics,  when  an 
external  force  is  applied  to  a  body  with  a  view  of  affecting 
its  inner  texture,  if  we  wish  to  predict  the  result,  we  must 
know  whether  the  external  force  conspires  with  or  opposes 
the  internal  forces  of  the  body  itself;  and  in  bringing  the 
influence  of  education  to  bear  upon  the  new-born  man  his 
inner  powers  also  must  be  taken  into  account.  He  comes 
to  us  as  a  bundle  of  inherited  capacities  and  tendencies, 
labeled  "from  the  indefinite  past  to  the  indefinite  future;" 
and  he  makes  his  transit  from  the  one  to  the  other 

*  Delivered  at  University  College,  London,  Session  1868-69. 


AN  ADDRESS  TO  STUDENTS.  41 1 

through  the  education  of  the  present  time.  The  object  of 
that  education  is,  or  ought  to  be,  to  provide  wise  exercise 
for  his  capacities,  wise  direction  for  his  tendencies,  and 
through  this  exercise  and  this  direction  to  furnish  his 
mind  with  such  knowledge  as  may  contribute  to  the  use- 
fulness, the  beauty,  and  the  nobleness  of  his  life. 

How  is  this  discipline  to  be  secured,  this  knowledge 
imparted?  Two  rival  methods  now  solicit  attention — the 
one  organized  and  equipped,  the  labor  of  centuries  having 
been  expended  in  bringing  it  to  its  present  state  of  per- 
fection; the  other,  more  or  less  chaotic,  but  becoming  daily 
less  so,  and  giving  signs  of  enormous  power,  both  as  a 
source  of  knowledge  and  as  a  means  of  discipline.  These 
two  methods  are  the  classical  and  the  scientific  method.  I 
Avish  they  were  not  rivals;  it  is  only  bigotry  and  short- 
sightedness that  make  them  so;  for  assuredly  it  is  possible 
to  give  both  of  them  fair  play.  Though  hardly  authorized 
to  express  an  opinion  upon  the  subject,  I  nevertheless  hold 
the  opinion -that  the  proper  study  of  a  language  is  an 
intellectual  discipline  of  the  highest  kind.  If  I  except 
discussions  on  the  comparative  merits  of  Popery  and 
Protestantism,  English  grammar  was  the  most  important 
discipline  of  my  boyhood.  The  piercing  through  tke 
involved  and  inverted  sentences  of  "Paradise  Lost;"  the 
linking  of  the  verb  to  its  often  distant  nominative,  of  the 
relative  to  its  distant  antecedent,  of  the  agent  to  the  object 
of  the  transitive  verb,  of  the  preposition  to  the  noun  or 
pronoun  which  it  governed,  the  study  of  variations  in  mood 
and  tense,  the  transpositions  often  necessary  to  bring  out 
the  true  grammatical  structure  of  a  sentence — all  this  was 
to  rny  young  mind  a  discipline  of  the  highest  value,  and  a 
source  of  unflagging  delight.  How  I  rejoiced  when  I  found 
a  great  author  tripping,  and  was  fairly  able  to  pin  him  to 
a  corner  from  which  there  was  no  escape!  As  I  speak, 
some  of  the  sentences  which  exercised  me  when  a  boy  rise 
to  my  recollection.  For  instance,  "  He  that  hath  ears  to 
hear,  let  him  hear;"  where  the  "  He"  is  left,  as  it  were, 
floating  in  mid  air  without  any  verb  to  support  it.  I 
speak  thus  of  English  because  it  was  of  real  value  to  me. 
I  do  not  speak  of  other  languages  because  their  educational 
value  for  me  was  almost  insensible.  But  knowing  the 
value  of  English  so  well,  I  should  be  the  last  to  deny,  or 
even  to  doubt,  the  high  discipline  involved  in  the  proper 
study  of  Latin  and  Greek. 


412  FRAGMENTS  OF  SCIENCE. 

That  study,  moreover,  has  other  merits  and  recommen- 
dations. It  is,  as  I  have  said,  organized  and  systematized 
by  long-continued  use.  It  is  an  instrument  wielded  by 
some  of  our  best  intellects  in  the  education  of  youth;  and 
it  can  point  to  results  in  the  achievements  of  our  fore- 
most men.  What,  then,  has  science  to  offer  which  is  in 
the  least  degree  likely  to  compete  with  such  a  system?  I 
cannot  better  reply  than  by  recurring  to  the  grand  old 
story  from  which  I  have  already  quoted.  Speaking  of  the 
world  and  all  that  therein  is,  of  the  sky  and  the  stars 
around  it,  the  ancient  writer  says,  "And  God  saw  all  that 
he  had  made,  and  behold  it  was  very  good."  It  is  the  body 
of  things  thus  described  which  science  offers  to  the  study 
of  man.  There  is  a  very  renowned  argument  much  prized 
and  much  quoted  bv  theologians,  in  which  the  universe  is 
compared  to  a  watch.  Let  us  deal  practically  with  this 
comparison.  Supposing  a  watch-maker,  having  completed 
his  instrument,  to  be  so  satisified  with  his  work  as  to  call  it 
very  good,  what  would  you  understand  him  to  mean? 
You  would  not  suppose  that  he  referred  to  the  dial-plate 
in  front  and  the  chasing  of  the  case  behind,  so  much  as  to 
the  wheels  and  pinions,  the  springs  and  jeweled  pivots  of 
the  works  within — to  those  qualities  and  powers,  in 
short,  which  enable  the  watch  to  perform  its  work  as 
a  keeper  of  time.  With  regard  to  the  knowledge  of 
such  a  watch  he  would  be  a  mere  ignoramus  who  would 
content  himself  with  outward  inspection.  I  do  not 
wish  to  say  one  severe  word  here  to-day,  but  I  fear  that 
many  of  those  who  are  very  loud  in  their  praise  of  the  works 
of  the  Lord  know  them  only  in  this  outside  and  superficial 
way.  It  is  the  inner  works  of  the  universe  which  science 
reverently  uncovers;  it  is  the  study  of  these  that  she  recom- 
mends as  a  discipline  worthy  of  all  acceptation. 

The  ultimate  problem  of  physics  is  to  reduce  matter  by 
analysis  to  its  lowest  condition  of  divisibility,  and  force  to 
its  simplest  manifestations,  and  then  by  synthesis  to  con- 
struct from  these  elements  the  world  as  it  stands.  We  are 
still  a  long  way  from  the  final  solution  of  this  problem;  and 
when  the  solution  comes,  it  will  be  more  one  of  spiritual 
insight  than  of  actual  observation.  But  though  we  are 
still  a  long  way  from  this  complete  intellectual  mastery  of 
nature,  we  have  conquered  vast  regions  of  it,  have  learned 
their  polities  and  the  play  of  their  powers.  We  live  upon  a, 


Atf  ADbRfiSS  TO  STUDENIS.  413 

ball  of  8,000  miles  in  diameter,  swathed  by  an  atmosphere 
of  unknown  height.  This  ball  has  been  molten  by  heat, 
chilled  to  a  solid,  and  sculptured  by  water.  It  is  made  up 
of  substances  possessing  distinctive  properties  and  modes 
of  action,  which  offer  problems  to  the  intellect,  some 
profitable  to  the  child,  others  taxing  the  highest  powers  of 
the  philosopher.  Our  native  sphere  turns  on  its  axis,  and 
revolves  in  space.  It  is  one  of  a  band  which  all  do  the 
same.  It  is  illuminated  by  a  sun  which,  though  nearly  a 
hundred  millions  of  miles  distant,  can  be  brought  virtually 
into  our  closets  and  there  subjected  to  examination.  It 
has  its  winds  and  clouds,  its  rain  and  frost,  its  light,  heat, 
sound,  electricity,  and  magnetism.  And  it  has  its  vast 
kingdoms  of  animals  and  vegetables.  To  a  most  amazing 
extent  the  human  mind  lias  conquered  these  things,  and 
revealed  the  logic  which  runs  through  them.  Were  they 
facts  only,  without  logical  relationship,  science  might,  as 
a  means  of  discipline,  suffer  in  comparison  with  language. 
But  the  whole  body  of  phenomena  is  instinct  with  law; 
the  facts  are  hung  on  principles,  and  the  value  of  physical 
science  as  a  means  of  discipline  consists  in  the  motion  of 
the  intellect,  both  inductively  and  deductively,  along  the 
lines  of  law  marked  out  by  phenomena.  As  regards  the 
discipline  to  which  I  have  already  referred  as  derivable 
from  the  study  of  languages — that,  and  more,  is  involved  in 
the  study  of  physical  science.  Indeed,  I  believe  it  would 
be  possible  so  to  limit  and  arrange  the  study  of  a  portion  of 
physics  as  to  render  the  mental  exercise  involved  in  it 
almost  qualitatively  the  same  as-that  involved  in  the  un- 
raveling of  a  language. 

I  have  thus  far  confined  myself  to  the  purely  intellectual 
iside  of  this  question.  But  man  is  not  all  intellect.  If  he 
were  so,  science  would,  I  believe,  be  his  proper  nutriment. 
But  he  feels  as  well  as  thinks;  he  is  receptive  of  the 
sublime  and  beautiful  as  well  as  of  the  true.  Indeed,  I 
believe  that  even  the  intellectual  action  of  a  complete  man 
is,  consciously  or  unconsciously,  sustained  by  an  under- 
current of  the  emotions.  It  is  vain  to  attempt  to  separate 
the  moral  and  emotional  from  the  intellectual.  Let  a  man 
but  observe  himself,  and  he  will,  if  I  mistake  not,  find 
that  in  nine  cases  out  of  ten  the  emotions  constitute  the 
motive  force  which  pushes  his  intellect  into  action.  The 
reading  of  the  works  of  two  men,  neither  of  them  imbued 


41 4  PR  A  OMENTS  0  F  SUIKNGtf. 

with  the  spirit  of  modern  science— neither  of  them,  indeed, 
friendly  to  that  spirit — has  placed  me  here  to-day.  These 
men  are  the  English  Carlyle  and  the  American  Emerson. 
I  must  ever  gratefully  remember  that  through  three  long 
cold  German  winters  Carlyle  placed  me  in  my  tub,  even 
when  ice  was  on  its  surface,  at  five  o'clock  every  morning 
— not  slavishly,  but  cheerfully,  meeting  each  day's  studies 
with  a  resolute  will,  determined  whether- victor  or  van- 
quished not  to  shrink  from  difficulty.  I  never  should  have 
gone  through  Analytical  Geometry  and  the  Calculus  had 
it  not  been  for  those  men.  I  never  should  have  become  a 
physical  investigator,  and  hence  without  them  I  should 
not  have  been  here  to-day.  They  told  me  what  I  ought  to 
do  in  a  way  that  caused  me  to  do  it,  and  all  my  consequent 
intellectual  action  is  to  be  traced  to  this  purely  moral 
source.  To  Carlyle  and  Emerson  I  ought  to  add  Fichte, 
the  greatest  representative  of  pure  idealism.  These  three 
unscientific  men  made  me  a  practical  scientific  worker. 
They  called  out  "  Act!"  I  hearkened  to  the  summons, 
taking  the  liberty,  however,  of  determining  for  myself  the 
direction  which  effort  was  to  take. 

And  I  may  now  cry  -'Act!"  but  the  potency  of  action 
must  be  yours.  I  may  pull  the  trigger,  but  if  the  gun  be 
not  charged  there  is  no  result.  We  are  creators  in  the 
intellectual  world  as  little  as  in  the  physical.  We  may 
remove  obstacles,  and  render  latent  capacities  active,  but 
we  cannot  suddenly  change  the  nature  of  man.  The  "  new 
birth  "  itself  implies  the  pro-existence  of  a  character  which 
requires  not  to  be  created  but  brought  forth.  You  cannot 
by  any  amount  of  missionary  labor  suddenly  transform  the 
savage  into  the  civilized  Christian.  The  improvement  of 
man  is  secular — not  the  work  of  an  hour  or  of  a  day.  But 
though  indubitably  bound  by  our  organizations,  no  man 
knows  what  the  potentialities  of  any  human  mind  may  be, 
requiring  only  release  to  be  brought  into  action.  There 
are  in  the  mineral  world  certain  crystals — certain  forms, 
for  instance,  of  fluor-spar,  which  have  lain  darkly  in  the 
earth  for  ages,  but  which  nevertheless  have  a  potency  of 
light  locked  up  within  them.  In  their  case  the  potential 
has  never  become  actual — the  light  is  in  fact  held  back  by 
a  molecular  detent.  When  these  crystals  are  warmed,  the 
detent  is  lifted,  and  an  outflow  of  light  immediately  begins. 
•I  know  not  how  many  of  you  may  be  in  the  condition  of 


AN  ADDRESS  TO  STUDENTS.  415 

this  fluor-spar.  For  aught  I  know,  every  one  of  you  may 
be  in  this  condition,  requiring  but  the  proper  agent  to  be 
applied — the  proper  word  to  be  spoken — to  remove  a  detent, 
and  to  render  you  conscious  of  light  and  warmth  within 
yourselves  and  sources  of  both  to  others. 

The  circle  of  human  nature,  then,  is  not  complete  with- 
out the  arc  of  the  emotions.  The  lilies  of  the  field  have  a 
value  for  us  beyond  their  botanical  ones — a  certain  light- 
ening of  the  heart  accompanies  the  declaration  that 
"Solomon  in  all  his  glory  was  not  arrayed  like  one  of 
these."  The  sound  of  the  village  bell  has  a  value  beyond 
its  acoustical  one.  The  setting  sun  has  a  value  beyond  its 
optical  one.  The  starry  heavens,  as  you  know,  had  for 
Immanuel  Kant  a  value  beyond  their  astronomical  one.  I 
think  it  very  desirable  to  keep  this  horizon  of  the  emotions 
open,  and  not  to  permit  either  priest  or  philosopher  to 
draw  down  his  shutters  between  you  and  it.  Here  the  dead 
languages,  which  are  sure  to  be  beaten  by  science  in  the 
purely  intellectual  fight,  have  an  irresistible  claim.  They 
supplement  the  work  of  science  by  exalting  and  refining 
the  aesthetic  faculty,  and  must  on  this  account  be  cherished^ 
by  all  who  desire  to  see  human  culture  complete.  There 
must  be  a  reason  for  the  fascination  which  these  languages 
have  so  long  exercised  upon  powerful  and  elevated  minds  — 
a  fascination  which  will  probably  continue  for  men  of 
Greek  and  Roman  mold  to  the  end  of  time. 

In  connection  with  this  question  one  very  obvious  danger 
besets  many  of  the  more  earnest  spirits  of  our  day — the 
danger  of  haste  in  endeavoring  to  give  the  feelings  repose. 
We  are  distracted  by  systems  of  theology  and  philosophy 
which  were  taught  to  us  when  -young,  and  which  now' 
excite  in  us  a  hunger  and  a  thirst  for  knowledge  not  proved 
to  be  attainable.  There  are  periods  when  the  judgment 
ought  to  remain  in  suspense,  the  data  on  which  a  decision 
might  be  based  being  absent.  This  discipline  of  suspending 
the  judgment  is  a  common  one  in  science,  but  not  so 
common  as  it  ought  to  be  elsewhere.  I  walked  down 
Regent  Street  some  time  ago  with  a  man  of  great  gifts  and 
acquirements,  discussing  with  him  various  theological  ques- 
tions. I  could  not  accept  his  views  of  the  origin  and  des- 
tiny of  the  universe,  nor  was  I  prepared  to  enunciate  any 
definite  views  of  my  own.  He  turned  to  me  at  length  and 
said,  "  You  surely  must  have  a  theory  of  the  universe." 


416  FRAGMENTS  OF  SCIENCE. 

That  I  should  in  one  way  or  another  have  solved  this  mys* 
tery  of  mysteries  seemed  to  my  friend  a  matter  of  course. 
"  I  have  not  even  a  theory  of  magnetism  "  was  my  reply. 
We  ought  to  learn  to  wait.  We  ought  assuredly  to  pause 
before  closing  with  the  advances  of  those  expounders  of 
the  ways  of  God  to  men,  who  offer  us  intellectual  peace  at 
the  modest  cost  of  intellectual  life. 

The  teachers  of  the  world  ought  to  be  its  best  men,  and 
for  the  present  at  all  events  such  men  must  learn  self-trust. 
By  the  fullness  and  freshness  of  their  own  lives  and  utter- 
euces  they  must  awaken  life  in  others.  The  hopes  and 
terrors  which  influenced  our  fathers  are  passing  away,  and 
our  trust  henceforth  must  rest  on  the  innate  strength  of 
man's  moral  nature.  And  here,  I  think,  the  poet  will 
have  a  great  part  to  play  in  the  future  culture  of  the  world. 
To  him,  when  he  rightly  understands  his  mission,  and  does 
not  flinch  from  the  tonic  discipline  which  it  assuredly 
demands,  we  have  a  right  to  look  for  that  heightening  and 
brightening  of  life  which  so  many  of  us  need.  To  him  it  is 
given  for  a  long  time  to  come  to  fill  those  shores  which  the 
recession  of  the  theologic  tide  has  left  exposed.  Void  of 
offense  to  science,  he  may  freely  deal  with  conceptions 
which  science  shuns,  and  become  the  illustrator  and 
interpreter  of  that  Power  which  as 

"  Jehovah,  Jove,  or  Lord," 

has  hitherto  filled  and  strengthened  the  human  heart. 

Let  me  utter  one  practical  word  in  conclusion — take  care 
of  your  health.  There  have  been  men  who  by  wise  atten- 
tion to  this  point  might  have  risen  to  any  eminence — 
might  have  made  great  discoveries,  written  great  poems, 
commanded  armies,  or  ruled  states,  but  who  by  unwise 
neglect  of  this  point  have  come  to  nothing.  Imagine  Her- 
cules as  oarsman  in  a  rotten  boat;  what  can  he  do  there 
but  by  the  very  force  of  his  stroke  expedite  the  ruin  of  his 
craft?  Take  care  then  of  the  timbers  of  your  boat,  and 
avoid  all  practices  likely  to  introduce  either  wet  or  dry  rot 
among  them.  And  this  is  not  to  be  accomplished  by 
desultory  or  intermittent  efforts  of  the  will,  but  by  the  for- 
mation of  habits.  The  will  no  doubt  has  sometimes  to  put 
forth  its  strength  in  order  to  crush  the  special  temptation. 
But  the  formation  of  right  habits  is  essential  to  your  per- 


USE  OF  THK  IMAGINATION.  417 

maneut  security.  They  diminish  your  chance  of  falling 
when  assailed,  and  they  augment  your  chance  of  recovery 
when  overthrown. 


CHAPTER  XXX. 

SCIENTIFIC   USE   OF  THE  IMAGINATION.* 

"  If  tbou  would'st  know  the  mystic  song 
Chaunted  when  the  sphere  was  young, 
Aloft,  abroad  the  paean  swells, 
Oh  wise  man,  hear'st  thou  half  it  tells? 
To  the  open  ear  it  sings 
The  early  genesis  of  things; 
Of  tendency  through  endless  ages 
Of  star-dust  and  star-pilgrimages, 
Of  rounded  worlds,  of  space  and  time, 
Of  the  old  floods'  subsiding  slime, 
Of  chemic  matter,  force  and  form, 
Of  poles  and  powers,  cold,  wet,  and  warm. 
The  rushing  metamorphosis 
Dissolving  all  that  fixture  is, 
Melts  things  that  be  to  things  that  seem, 
And  solid  nature  to  a  dream." 

EMERSON. 

"  Was  war'  ein  Gott  der  nur  von  aussen  stieose, 
Im  Kreis  das  All  am  Finger  laufen  liesse 
Ihm  ziemt's,  die  Welt  im  Innern  zu  bewegen, 
Natur  in  Sich,  Sich  in  Natur  zu  hegen." 

GOETHE. 


Lastly,  physical  investigation,  more  than  anything  besides,  helps 
each  us  the  actual  value,and  right  use  of  the  Imagination  —  of  that 
wondrous  faculty,  which,  left  to  ramble  uncontrolled,  leads  us  astray 


into  a  wilderness  of  perplexities  and  errors,  a  land  of  mists  and 
shadows;  but  which,  properly  controlled  by  experience  and  reflection, 
becomes  the  noblest  attribute  of  man;  the  source  of  poetic  genius,  the 
instrument  of  discovery  in  Science,  without  the  aid  of  which  Newton 
would  never  have  invented  fluxions,  nor  Davy  have  decomposed  the 
earths  and  alkalies,  nor  would  Columbus  have  found  another  conti- 
nent."— Address  to  the  Royal  Society  by  its  President  Sir  Benjamin 
Brodie,  November  30,  1859. 

I  CARRIED  with  me  to  the  Alps  this  year  the  burden  of 
this  evening's  work.  Save  from  memory  I  had  no  direct 
aid  upon  the  mountains;  but  to  spur  up  the  emotions,  on 

*  Discourse  delivered  before  the  British  Association  at  Liverpool, 
September  16,  1870. 


418  FRAGMENTS  OF  SCIENCE. 

which  so  much  depends,  as  well  as  to  nourish  indirectly 
the  intellect  and  will,  I  took  with  me  four  works,  com- 
prising two  volumes  of  poetry,  Goethe's  "  Farbenlehre," 
and  the  work  on  "Logic  "  recently  published  by  Mr.  Alex- 
ander Bain.  In  Goethe,  so  noble  otherwise,  I  chiefly 
noticed  the  self-inflicted  hurts  of  genius,  as  it  broke  itself 
in  vain  against  the  philosophy  of  Newton.  Mr.  Bain  I 
found,  for  the  most  part,  learned  and  practical,  shining 
generally  with  a  dry  light,  but  exhibiting  at  times  a  flush 
of  emotional  strength,  which  proved  that  even  logicians 
share  the  common  fire  of  humanity.  He  interested  me 
most  when  he  became  the  mirror  of  my  own  condition. 
Neither  intellectually  nor  socially  is  it  good  for  man  to  be 
alone,  and  the  sorrows  of  thought  are  more  patiently  borne 
when  we  find  that  they  have  been  experienced  by  another. 
From  certain  passages  in  his  book  I  could  infer  that  Mr. 
Bain  was  no  stranger  to  such  sorrows.  Speaking  for  ex- 
ample of  the  ebb  of  intellectual  force,  which  we  all  fr6m 
time  to  time  experience,  Mr.  Bain  says:  "The  uncertainty 
where  to  look  for  the  next  opening  of  discovery  brings  the 
pain  of  conflict  and  the  debility  of  indecision."  These 
words  have  in  them  the  true  ring  of  personal  experience. 
The  action  of  the  investigator  is  periodic.  He  grapples 
with  a  subject  of  inquiry,  wrestles  with  it,  and  exhausts,  it 
may  be,  both  himself  and  it  for  the  time  being.  He 
breathes  a  space,  and  then  renews  the  struggle  in  another 
field.  Now  this  period  of  halting  between  two  investi- 
gations is  not  always  one  of  pure  repose.  It  is  often  a 
period  of  doubt  and  discomfort — of  gloom  and  ennui. 
"  The  uncertainty  where  to  look  for  the  next  opening 
of  discovery  brings  the  pain  of  conflict  and  the  debility  of 
indecision."  It  was  under  such  conditions  that  I  had  to 
equip  myself  for  the  hour  and  the  ordeal  that  are  now 
come. 

The  disciplines  of  common  life  are,  in  great  part,  exer- 
cises in  the  relations  of  space,  or  in  the  mental  grouping 
of  bodies  in  space;  and,  by  such  exercises,  the  public 
mind  is,  to  some  extent,  prepared  for  the  reception  of 
physical  conceptions.  Assuming  this  preparation  on  your 
part,  the  wisji  gradually  grew  within  me  to  trace,  and  to 
enable  you  to  trace,  some  of  the  more  occult  features  and 
operations  of  Light  and  Color.  I  wished,  if  possible, 


USE  OF  THE  IMA  GIN  A  TION.  419 

to  take  you  beyond  the  boundary  of  mere  observation, 
into  a  region  where  things  are  intellectually  discerned, 
and  to  show  you  there  the  hidden  mechanism  of  optical 
action. 

But  how  are  those  hidden  things  to  be  revealed?  Philos- 
ophers may  be  right  in  affirming  that  we  cannot  transcend 
experience:  we  can,  at  all  events,  carry  it  a  long  way  from 
its  origin.  We  can  magnify,  diminish,  qualify,  and  com- 
bine experiences,  so  as  to  render  them  fit  for  purposes 
entirely  new.  In  explaining  sensible  phenomena,  we 
habitually  form  mental  images  of  the  ultra-sensible.  There 
are  Tories  even  in  science  who  regard  Imagination  as  a 
faculty  to  be  feared  and  avoided  rather  than  employed. 
They  have  observed  its  action  in  weak  vessels,  and  are  un- 
duly impressed  by  its  disasters.  But  they  might  with 
equal  justice  point  to  exploded  boilers  as  an  argument 
against  the  use  of  steam.  With  accurate  experiment  and 
observation  to  work  upon,  Imagination  becomes  the  archi- 
tect of  physical  theory.  Newton's  passage  from  a  falling 
apple  to  a  falling  moon  was  an  act  of  the  prepared  imagi- 
nation, without  which  the  "  laws  of  Kepler"  could  never 
have  been  traced  to  their  foundations.  Out  of  the  facts  of 
chemistry  the  constructive  imagination  of  Dal  ton  formed 
the  atomic  theory.  Davy  was  richly  endowed  with  the 
imaginative  faculty,  while  with  Faraday  its  exercise  was 
incessant,  preceding,  accompanying  and  guiding  all  his 
experiments.  His  strength. and  fertility  as  a  discoverer  is 
to  be  referred  in  great  part  to  the  stimulus  of  his  imagina- 
tion. Scientific  men  fight  shy  of  the  word  because  of  its- 
ultra-scientific  connotations;  but  the  fact  is  that  without 
the  exercise  of  this  power,  our  knowledge  of  nature  would 
be  a  mere  tabulation  of  co-existences  and  sequences.  We 
should  still  believe  in  the  succession  of  day  and  night,  of 
summer  and  winter;  but  the  conception  of  Force  would 
vanish  from  our  universe;  causal  relations  would  disappear, 
and  with  them  that  science  which  is  now  binding  the  parts 
of  nature  to  an  organic  whole. 

I  should  like  to  illustrate  by  a  few  simple  instances  the 
use  that  scientific  men  have  already  made  of  this  power  of 
imagination,  and  to  indicate  afterward  some  of  the  further 
uses  that  they  are  likely  to  make  of  it.  Let  us  begin  with 
the  rudimentary  experiences.  Observe  the  falling  of  heavy 
rain-drops  into  a  tranquil  pond.  Each  drop  as  it  strikes 


420  FRAGMENTS  OF  SCIENCE. 

the  water  becomes  a  center  of  disturbance,  from  which  i. 
series  of  ring-ripples  expand  outward.  Gravity  and  inertia 
are  the  agents  by  which  this  wave-motion  is  produced,  and 
a  rough  experiment  will  suffice  to  show  that  the  rate  of 
propagation  does  not  amount  to  a  foot  a  second.  A  series 
of  slight  mechanical  shocks  is  experienced  by  a  body  plunged 
in  the  water,  as  the  wavelets  reach  it  in  succession.  But  a 
finer  motion  is  at  the  same  time  set  up  and  propagated.  If 
the  head  and  ears  be  immersed  in  the  water,  as  in  an  exper- 
iment of  Franklin's,  the  tick  of  the  drop  is  heard.  Now, 
this  sonorous  impulse  is  propagated,  not  at  the  rate  of  a 
foot,  but  at  the  rate  of  4,700  feet  a  second.  In  this  case 
it  is  not  the  gravity  but  the  elasticity  of  the  water  that 
comes  into  play.  Every  liquid  particle  pushed  against  its 
neighbor  delivers  up  its  motion  with  extreme  rapidity, 
and  the  pulse  is  propagated  as  a  thrill.  The  incom- 
pressibility  of  water,  as  illustrated  by  the  famous  Floren- 
tine experiment,  is  a  measure  of  its  elasticity;  and  to 
the  possession  of  this  property,  in  so  high  a  degree,  the 
rapid  transmission  of  a  sound-pulse  through  water  is  to  be 
ascribed. 

But  water,  as  you  know,  is  not  necessary  to  the  con- 
duction of  sound;  air  is  its  most  common  vehicle.  And 
you  know  that  when  the  air  possesses  the  particular  density 
and  elasticity  corresponding  to  the  temperature  of  freezing 
water,  the  velocity  of  sound  in  it  is  1,090  feet  a  second. 
It  is  almost  exactly  one-fourth  of  the  velocity  in  water; 
the  reason  being  that  though  the  greater  weight  of  the 
water  tends  to  diminish  the  velocity,  the  enormous  molec- 
ular elasticity  of  the  liquid  far  more  than  atones  for  the 
disadvantage  due  to  weight.  By  various  contrivances  we 
can  compel  the  vibrations  of  the  air  to  declare  themselves; 
we  know  the  length  and  frequency  of  the  sonorous  waves, 
and  we  have  also  obtained  great  mastery  over  the  various 
methods  by  which  the  air  is  thrown  into  vibration.  We 
know  the  phenomena  and  laws  of  vibrating  rods,  of  organ- 
pipes,  strings,  membranes,  plates,  and  bells.  We  can 
abolish  one  sound  by  another.  We  know  the  physical 
meaning  of  music  and  noise,  of  harmony  and  discord.  In 
short,  as  regards  sound  in  general,  we  have  a  very  clear 
notion  of  the  external  physical  processes  which  correspond 
to  our  sensations. 

In  the  phenomena  of  sound^  we  travel  a  very  little  way 


USE  OF  THE  IMAGINATION.  421 

from  downright  sensible  experience.  Still  the  imagination 
is  to  some  extent  exercised.  The  bodily  eye,  for  example, 
cannot  see  the  condensations  and  rarefactions  of  the  waves 
of  sound.  We  construct  them  in  thought,  and  we  believe 
as  firmly  in  their  existence  as  in  that  of  the  air  itself.  But 
now  our  experience  is  to  be  carried  into  a  new  region, 
where  a  new  use  is  to  be  made  of  it.  Having  mastered  the 
cause  and  mechanism  of  sound,  wo  desire  to  know  the 
cause  and  mechanism  of  light.  We  wish  to  extend  our 
inquiries  from  the  auditory  to  the  optic  nerve.  There  is 
in  the  human  intellect  a  power  of  expansion — 1  might 
almost  call  it  a  power  of  creation — which  is  brought  into 
play  by  the  simple  brooding  upon  facts.  The  legend  of 
the  spirit  brooding  over  chaos  may  have  originated  in  ex- 
perience of  this  power.  In  the  case  now  before  us  it  has 
manifested  itself  by  transplanting  into  space,  for  the  pur- 
poses of  light,  an  adequately  modified  form  of- the  mech- 
anism of  sound.  We  know  intimately  whereon  the  velocity 
of  sound  depends.  When  we  lessen  the  density  of  the 
aerial  medium,  and  preserve  its  elasticity  constant,  we  aug- 
ment the  velocity.  When  we  heighten  the  elasticity,  and 
keep  the  density  constant,  we  also  augment  the  velocity. 
A  small  density,  therefore,  and  a  great  elasticity,  are  the 
two  things  necessary  to  rapid  propagation.  Now  light  is 
known  to  move  with  the  astounding  velocity  of  186,000 
miles  a  second.  How  is  such  a  velocity  to  be  obtained? 
By  boldly  diffusing  in  space  a  medium  of  the  requisite 
tenuity  and  elasticity. 

Let  us  make  such  a  medium  our  starting-point,  and, 
endowing  it  with  one  or  two  other  necessary  qualities,  let 
us  handle  it  in  accordance  with  strict  mechanical  laws. 
Let  us  then  carry  our  results  from  the  world  of  theory  into 
the  world  of  sense,  and  see  whether  our  deductions  do  not 
issue  in  the  very  phenomena  of  light  which  ordinary  knowl- 
edge and  skilled  experiment  reveal.  If  in  all  the  multi- 
plied varieties  of  these  phenomena,  including  those  of  the 
most  remote  and  entangled  description,  this  fundamental 
conception  always  bring  us  face  to  face  with  the  truth;  if 
no  contradiction  to  our  deductions  from  it  be  found  in 
external  nature,  but  on  all  sides  agreement  and  verifica- 
tion; if,  moreover,  as  in  the  case  of  Conical  Refraction  and 
in  other  cases,  it  actually  forces  upon  our  attention  phe- 
nomena which  no  eye  had  previously  seen,  and  which  no 


422  FRAGMENTS  OP  SCIENCE. 

mind  bad  previously  imagined — such  a  conception,  must, 
we  think,  be  something  more  than  a  mere  figment  of  the 
scientific  fancy.  In  forming  it,  that  composite  and  creative 
power,  in  which  reason  and  imagination  are  united,  has,  we 
believe,  led  us  into  a  world  not  less  real  than  that  of  the 
senses,  and  of  which  the  world  of  sense  itself  is  the  sugges- 
tion and,  to  a  great  extent,  the  outcome. 

Far  be  it  from  me,  however,  to  wish  to  fix  yon  immov- 
ably in  this  or  in  any  other  theoretic  conception.  With 
all  our  belief  of  it,  it  will  be  well  to  keep  the  theory  of  a 
lumiuiferous  ether  plastic  and  capable  of  change.  You 
may,  moreover,  urge  that,  although  the  phenomena  occur 
as  if  the  medium  existed,  the  absolute  demonstration  of  its 
existence  is  still  wanting.  Far  be  it  from  me  to  deny  to 
this  reasoning  such  validity  as  it  may  fairly  claim.  Let  us 
endeavor  by  means  of  analogy  to  form  a  fair  estimate  of 
its  force.  You  believe  that  in  society  you  are  surrounded 
by  reasonable  beings  like  yourself.  You  are,  perhaps,  as 
firmly  convinced  of  this  as  of  anything.  What  is  your 
warrant  for  this  conviction?  Simply  and  solely  this:  your 
fellow  creatures  behave  as  if  they  were  reasonable;  the 
hypothesis,  for  it  is  nothing  more,  accounts  for  the  facts. 
To  take  an  eminent  example:  you  believe  that  our 
president  is  a  reasonable  being.  Why?  There  is  no 
known  method  of  superposition  by  which  any  one  of  us 
can  apply  himself  intellectually  to  any  other,  so  as  to 
demonstrate  coincidence  as  regards  the  possession  of  reason. 
If,  therefore,  you  hold  our  president  to  be  reasonable, 
it  is  because  he  behaves  as  if  he  were  reasonable.  As 
in  the  case  of  the  ether,  beyond  the  "  as  if"  you  cannot 
go.  Nay,  I  should  not  wonder  if  a  close  comparison 
of  the  data  on  which  both  inferences  rest  caused  many 
respectable  persons  to  conclude  that  the  ether  had  the 
best  of  it. 

This  universal  medium,  this  light-ether  as  it  is  called,  is 
the  vehicle,  not  the  origin,  of  wave-motion.  It  receives 
and  transmits,  but  it  does  not  create.  Whence  does  it 
derive  the  motions  it  conveys?  For  the  most  part  from 
luminous  bodies.  By  the  motion  of  a  luminous  body  I  do 
not  mean  its  sensible  motion,  such  as  the  flicker  of  a  caudle, 
or  the  shooting  out  of  red  prominences  from  the  limb  of 
the  sun.  I  mean  an  intestine  motion  of  the  atoms  or  mole- 
cules of  the  luminous  body.  But  here  a  certain  reserve  is 


USB  OP  THE  IMAGINATION.  423 

necessary.  Many  chemists  of  the  present  day  refuse  to 
speak  of  atoms  and  molecules  as  real  things.  Their  caution 
leads  them  to  stop  short  of  the  clear,  sharp,  mechanically 
intelligible  atomic  theory  enunciated  by  Dalton,  or  any 
form  of  that  theory,  and  to  make  the  doctrine  of  "  mul- 
tiple proportions"  their  intellectual  bourne.  I  respect  the 
caution,  though  I  think  it  is  here  misplaced.  The  chemists 
who  recoil  from  these  notions  of  atoms  and  molecules 
accept,  without  hesitation,  the  Uudulatory  Theory  of 
Light.  Like  you  and  me  they  one  and  ail  believe  in  an 
ether  and  its  light-producing  waves.  Let  us  consider  what 
this  belief  involves.  Bring  your  imaginations  once  more 
into  play,  and  figure  a  series  of  sound-waves  passing 
through  air.  Follow  them  up  to  their  origin,  and  what 
do  you  there  find?  A  definite,  tangible,  vibrating  body. 
It  may  be  the  vocal  chords  of  a  human  being,  it  may  be 
an  organ-pipe,  or  it  may  be  a  stretched  string.  Follow  in 
the  same  manner  a  train  of  ether-waves  to  their  source; 
remembering  at  the  same  time  that  your  ether  is  matter, 
dense,  elastic,  and  capable  of  motions  subject  to,  and 
determined  by,  mechanical  laws.  What  then  do  you  ex- 
pect to  find  as  the  source  of  a  series  of  ether-waves?  Ask 
your  imagination  if  it  will  accept  a  vibrating  multiple 
proportion — a  numerical  ratio  in  a  state  of  oscillation? 
I  do  not  think  it  will.  You  cannot  crown  the  edifice 
with  this  abstraction1.  The  scientific  imagination, 
which  is  here  authoritative,  demands,  as  the  origin 
and  cause  of  a  series  of  ether-waves,  a  particle  of  vibrating 
matter  quite  as  definite,  though  it  may  be  excessively 
minute,  as  that  which  gives  origin  to  a  musical  sound. 
Such  a  particle  we  name  an  atom  or  a  molecule.  I 
think  the  intellect,  when  focused  so  as  to  give  definition 
without  penumbral  haze,  is  sure  to  realize  this  image  at 
the  last. 

With  the  view  of  preserving  thought  continuous 
throughout  this  discourse,  and  of  preventing  either  failure 
of  knowledge  or  of  memory,  from  causing  any  rent  in  our 
picture,  I  here  propose  to  run  rapidly  over  a  bit  of  ground 
which  is  probably  familiar  to  most  of  you,  but  which  I  am 
anxious  to  make  familiar  to  you  all.  The  waves  generated 
in  the  ether  by  the  swinging  atoms  of  luminous  bodies  are 
of  different  lengths  and  amplitudes.  The  amplitude  is  the 


424  FRAGMENTS  OF  SCIENCE. 

width  of  swing  of  the  individual  particles  of  the  waves.  In 
water-waves  it  is  the  vertical  height  of  the  crest  above  the 
trough,  while  the  length  of  the  wave  is  the  horizontal  dis- 
tance between  two  consecutive  crests.  The  aggregate  of 
waves  emitted  by  the  sun  may  be  broadly  divided  into  two 
classes:  the  one  class  competent,  the  other  incompetent,  to 
excite  vision.  But  the  light-producing  waves  differ  mark- 
edly among  themselves  in  size,  form,  and  force.  The 
length  of  the  largest  of  these  waves  is  about  twice  that  of 
the  smallest,  but  the  amplitude  of  the  largest  is  probably  a 
hundred  times  that  of  the  smallest.  Now  the  force " or 
energy  of  the  wave,  which,  expressed  with  reference  to  sen- 
sation, means  the  intensity  of  the  light,  is  proportional  to 
the  square  of  the  amplitude.  Hence  the  amplitude  being 
one-hundredfold,  the  energy  of  the  largest  light-giving 
waves  would  be  ten-thousandfold  that  of  the  smallest. 
This  is  not  improbable.  I  use  these  figures  not  with  a  view 
to  numerical  accuracy,  but  to  give  you  definite  ideas  of 
the  differences  that  probably  exist  among  the  light-giving 
waves.  And  if  we  take  the  whole  range  of  solar  radiation 
into  account — its  non-visual  as  well  as  its  visual  waves — I 
think  it  probable  that  the  force,  or  energy,  of  the  largest 
wave  is  more  than  a  million  times  that  of  the  smallest. 

Turned  into  their  equivalents  of  sensation,  the  different 
light-waves  produce  different  colors.  Eed,  for  example,  is 
produced  by  the  largest  waves,  violet  by  the  smallest,  while 
green  is  produced  by  a  wave  of  intermediate  length  and 
amplitude.  On  entering  from  air  into  a  more  highly 
refracting  substance,  such  as  glass  or  water,  or  the  sulphide 
of  carbon,  all  the  waves  are  retarded,  but  the  smallest  ones 
most.  This  furnishes  a  means  of  separating  the  different 
classes  of  waves  from  each  other;  in  other  words,  of  analyz- 
ing the  light.  Sent  through  a  refracting  prism,  the  waves 
of  the  sun.  are  turned  aside  in  different  degrees  from  their 
direct  course,  the  red  least,  the  violet  most.  They  are 
virtually  pulled  asunder,  and  they  paint  upon  a  white 
screen  placed  to  receive  them  "the  solar  spectrum." 
Strictly  speaking,  the  spectrum  embraces  an  infinity  of 
colors;  but  the  limits  of  language,  and  of  our  powers  of 
distinction,  cause  it  to  be  divided  into  seven  segments:  red, 
orange,  yellow,  green,  blue,  indigo,  violet.  These  are  the 
seven  primary  or  prismatic  colors. 

Separately,*  or  mixed  in  various  proportions,  the  solar 


USE  OF  THE  IMAGINATION.  425 

waves  yield  all  the  colors  observed  in  nature  and  employed 
in  art.  Collectively,  they  give  us  the  impression  of  white- 
ness. Pure  unsifted  solar  light  is  white;  and,  if  all  the 
wave  constituents  of  such  light  be  reduced  in  the  same 
proportion,  the  light,  though  diminished  in  intensity,  will 
still  be  white.  The  whiteness  of  snow  with  the  sun 
shining  upon  it,  is  barely  tolerable  to  the  eye.  The  same 
snow  under  an  overcast  firmament  is  still  white.  Such  a 
firmament  enfeebles  the  light  by  reflecting  it  upward;  and 
when  we  stand  above  a  cloud-field — on  an  Alpine  summit, 
for  instance,  or  on  the  top  of  Snowdon — and  see,  in  the 
proper  direction,  the  sun  shining  on  the  clouds  below  us, 
they  appear  dazzlingly  white.  Ordinary  clouds,  in  fact, 
divide  the  solar  light  impinging  on  them  into  two  parts — a 
reflected  part  and  a  transmitted  part,  in  each  of  which  the 
proportions  of  wave  motion  which  produce  the  impression 
of  whiteness  are  sensibly  preserved. 

It  will  be  understood  that  the  condition  of  whiteness 
would  fail  if  all  the  waves  were  diminished  equally,  or  by 
the  same  absolute  quantity.  They  must  be  reduced  pro- 
portionately, instead  of  equally.  If  by  the  act  of  reflection 
the  waves  of  red  light  are  split  into  exact  halves,  then,  to 
preserve  the  light  white,  the  waves  of  yellow,  orange, 
green,  and  blue,  must  also  be  split  into  exact  halves.  In 
short,  the  reduction  must  take  place,  not  by  absolutely 
equal  quantities,  but  by  equal  fractional  parts.  In  white 
light  the  preponderance,  as  regards  energy,  of  the  larger 
over  the  smaller  waves  must  always  be  immense.  Were  the 
case  otherwise,  the  visual  correlative,  blue,  of  the  smaller 
waves  would  have  the  upper  hand  in  our  sensations. 

Not  only  are  the  waves  of  ether  reflected  by  clouds,  by 
solids,  and  by  liquids,  but  when  they  pass  from  light  air  to 
dense,  or  from  dense  air  to  light,  a  portion  of  the  wave- 
motion  is  always  reflected.  Now  our  atmosphere  changes 
continually  in  density  from  top  to  bottom.  It  will  help 
our  conceptions  if  we  regard  it  as  made  up  of  a  series  of 
thin  concentric  layers,  or  shells  of  air,  each  shell  being  of 
the  same  density  throughout,  a  small  and  sudden  change 
of  density  occurring  in  passing  from  shell  to  shell.  Light 
would  be  reflected  at  the  limiting  surfaces  of  all  these 
shells,  and  their  action  would  be  practically  the  same  as 
that  of  the  real  atmosphere.  And  now  I  would  ask  your 
imagination  to  picture  this  act  of  reflection.  What  must 


426  FRAGMENTS  OF  SCIENCE. 

become  of  the  reflected  light?  The  atmospheric  layers 
turn  their  convex  surfaces  toward  the  sun;  they  are  so 
many  convex  mirrors  of  feeble  power;  and  you  will 
immediately  perceive  that  the  light  regularly  reflected  from 
these  surfaces  cannot  reach  the  earth  at  all,  but  is  dispersed 
in  space.  Light  thus  reflected  cannot,  therefore,  be  the 
light  of  the  sky. 

But,  though  the  sun's  light  is  not  reflected  in  this  fash- 
ion from  the  aerial  layers  to  the  earth,  there  is  indubitable 
evidence  to  show  that  the  light  of  our  firmament  is  scat- 
tered light.  Proofs  of  the  most  cogent  description  could 
be  here  adduced;  but  we  need  only  consider  that  we  receive 
light  at  the  same  time  from  all  parts  of  the  hemisphere  of 
heaven.  The  light  of  the  firmament  conies  to  us  across 
the  direction  of  the  solar  rays,  and  even  against  the  direc- 
tion of  the  solar  rays;  and  this  lateral  and  opposing  rush 
of  wave-motion  can  only  be  due  to  the  rebound  of  the 
waves  from  the  air  itself,  or  from  something  suspended  in 
the  air.  It  is  also  evident  that,  unlike  the  action  of  clouds, 
the  solar  light  is  not  reflected  by  the  sky  in  the  proportions 
which  produce  white.  The  sky  is  blue,  which  indicates  an 
excess  of  the  shorter  waves.  In  accounting  for  the  color 
of  the  sky,  the  first  question  suggested  by  analogy  would 
undoubtedly  be,  Is  not  the  air  blue?  The  blueness  of  the 
air  has,  in  fact,  been  given  as  a  solution  of  the  blueness  of 
the  sky.  But  how,  if  the  air  be  blue,  can  the  light  of  sun- 
rise and  sunset,  which  travels  through  vast  distances  of  air, 
be  yellow,  orange,  or  even  red?  The  passage  of  white  solar 
light  through  a  blue  medium  could  by  no  possibility  redden 
the  light.  The  hypothesis  of  a  blue  air  is  therefore 
untenable.  In  fact  the  agent,  whatever  it  is,  which  sends 
us  the  light  of  the  sky,  exercises  in  so  doing  a  dichroitic 
action.  The  light  reflected  is  blue,  the  light  transmitted 
is  orange  or  red.  A  marked  distinction  is  thus  exhibited 
between  the  matter  of  the  sky,  and  that  of  an  ordinary 
cloud,  which  exercises  no  such  dichroitic  action. 

By  the  scientific  use  of  the  imagination  we  may  hope  to 
penetrate  this  mystery.  The  cloud  takes  no  note  of  size 
on  the  part  of  the  waves  of  ether,  but  reflects  them  all 
alike.  It  exercises  no  selective  action.  Now  the  cause  of 
this  may  be  that  the  cloud  particles  are  so  large,  in  com- 
parison with  the  waves  of  ether,  as  to  reflect  them  all 
indifferently.  A  broad  cliff  reflects  an  Atlantic  roller  as 


USB  OF  THK  IMAGINATION.  427 

easily  as  a  ripple  produced  by  a  sea-bird's  wing;  and  in 
the  presence  of  large  reflecting  surfaces,  the  existing 
differences  of  magnitude  among  the  waves  of  ether  may 
disappear.  Buc  supposing  the  reflecting  particles,  instead 
of  being  very  large,  to  be  very  small  in  comparison  with 
the  size  of  the  waves.  In  this  case,  instead  of  the  whole 
wave  being  fronted  and  thrown  back,  a  small  portion  only 
is  shivered  off.  The  great  mass  of  the  wave  passes  over 
such  a  particle  without  reflection.  Scatter,  then,  a  hand- 
ful of  such  minute  foreign  particles  in  our  atmosphere,  and 
set  imagination  to  watch  their  action  upon  the  solar  waves. 
Waves  of  all  sizes  impinge  upon  the  particles,  and  you  see 
at  every  collision  a  portion  of  the  impinging  wave  struck 
off;  all  the  waves  of  the  spectrum,  from  the  extreme  red 
to  the  extreme  violet,  being  thus  acted  upon. 

Eemembering  that  the  red  waves  stand  to  the  blue  much 
in  the  relation  of  billows  to  ripples,  we  have  to  consider 
whether  those  extremely  small  particles  are  competent  to 
scatter  all  the  waves  in  the  same  proportion.  If  they  be 
not— and  a  little  reflection  will  make  it  clear  that  they 
are  not — the  production  of  color  must  be  an  incident  of 
the  scattering.  Largeness  is  a  thing  of  relation;  and  the 
smaller  the  wave,  the  greater  is  the  relative  size  of  any 
particle  on  which  the  wave  impinges,  and  the  greater  also 
the  ratio  of  the  portion  scattered  to  the  total  wave.  A 
pebble,  placed  in  the  way  of  the  ring- ripples  produced  by 
heavy  raindrops  on  a  tranquil  pond,  will  scatter  a  large 
fraction  of  each  ripple,  while  the  fractional  part  of  a  larger 
wave  thrown  back  by  the  same  pebble  might  be  infini- 
tesimal. Now  we  have  already  made  it  clear  to  our  minds 
that  to  preserve  the  solar  light  white,  its  constituent  pro- 
portions must  not  be  altered;  but  in  the  act  of  division 
performed  by  these  very  small  particles  the  proportions 
are  altered;  an  undue  fraction  of  the  smaller  waves  is 
scattered  by  the  particles,  and;  as  a  consequence,  in  the 
scattered  light,  blue  will  be  the  predominant  color.  The 
other  colors  of  the  spectrum  must,  to  some  extent,  be 
associated  with  the  blue.  They  are  not  absent,  but 
deficient.  We  ought,  in  fact,  to  have  them  all,  but  in 
diminishing  proportions,  from  the  violet  to  the  red. 

We  have  here  presented  a  case  to  the  imagination,  and, 
assuming  the  undulatory  theory  to  be  a  reality,  we  have, 
I  think,  fairly  reasoned  our  way  to  the  conclusion,  that 


428  FRAGMENTS  OF  SCIENCE* 

were  particles,  small  in  comparison  to  the  sizes  of  the  ether 
waves,  sown  in  our  atmosphere,  the  light  scattered  by 
those  particles  would  be  exactly  such  as  we  observe  in  our 
azure  skies.  When  this  light  is  analyzed,  all  the  colors  of 
the  spectrum  are  found,  and  they  are  found  in  the  pro- 
portions indicated  by  our  conclusion.  Blue  is  not  the  sole, 
but  it  is  the  predominant  color. 

Let  us  now  turn  our  attention  to  the  light  which  passes 
unscattered  among  the  particles.  How  must  it  be  finally 
affected?  By  its  successive  collisions  with  the  particles  the 
white  light  is  more  and  more  robbed  of  its  shorter  waves; 
it  therefore  loses  more  and  more  of  its  due  proportion  of 
blue.  The  result  may  be  anticipated.  The  transmitted 
light,  where  short  distances  are  involved,  will  appear 
yellowish.  But  as  the  sun  sinks  toward  the  horizon  the 
atmospheric  distances  increase,  and  consequently  the 
number  of  the  scattering  particles.  They  abstract  in 
succession  the  violet,  the  indigo,  the  blue,  and  even  disturb 
the  proportions  of  green.  The  transmitted  light  under 
such  circumstances  must  pass  from  yellow  through  orange 
to  red.  This  also  is  exactly  what  we  find  in  nature. 
Thus,  while  the  reflected  light  gives  us  at  noon  the  deep 
azure  of  the  Alpine  skies,  the  transmitted  light  ives  us  at 
sunset  the  warm  crimson  of  the  Alpine  snows.  The 
phenomena  certainly  occur  as  if  our  atmosphere  were  a 
medium  rendered  slightly  turbid  by  the  mechanical  sus- 
pension of  exceedingly  small  foreign  particles. 

Here,  as  before,  we  encounter  our  skeptical  "as  if." 
It  is  one  of  the  parasites  of  science,  ever  at  hand,  and  ready 
to  plant  itself  and  sprout,  if  it  can,  on  the  weak  points  of 
our  philosophy.  But  a  strong  constitution  defies  the 
parasite,  and  in  our  case,  as  we  question  the  phenomena, 
probability  grows  like  growing  health,  until  in  the  end  the 
malady  of  doubt  is  completely  extirpated.  The  first 
question  that  naturally  arises  is  this:  Can  small  particles 
be  really  proved  to  act  in  the  manner  indicated?  No 
doubt  of  it.  Each  one  of  you  can  submit  the  question  to 
an  experimental  test.  Water  will  not  dissolve  resin,  but 
spirit  will  dissolve  it;  and  when  spirit  holding  resin  in 
solution  is  dropped  into  water,  the  resin  immediately 
separates  in  solid  particles,  which  render  the  water  milky. 
The  coarseness  of  this  precipitate  depends  on  the  quantity 
of  the  dissolved  resin.  You  can  cause  it  to  separate  either 


USE  OF  THE  IMAGINATION.  429 

in  thick  clots  or  in  exceedingly  fine  particles.  Professor 
Briicke  has  given  us  the  proportions  which  produce  particles 
particularly  suited  to  our  present  purpose.  One  gramme 
of  clean  mastic  is  dissolved  in  eighty-seven  grammes  of 
absolute  alcohol,  and  the  transparent  solution  is  allowed  to 
drop  into  a  beaker  containing  clear  water,  kept  briskly 
stirred.  An  exceedingly  fine  precipitate  is  thus  formed, 
which  declares  its  presence  by  its  action  upon  light. 
Placing  a  dark  surface  behind  the  beaker,  and  permitting 
the  light  to  fall  into  it  from  the  top  or  front,  the  medium 
is  seen  to  be  distinctly  blue.  It  is  not  perhaps  so  perfect 
a  blue  as  rn;iy  be  seen  on  exceptional  days  among  the  Alps, 
but  it  is  a  very  fair  sky-blue.  A  trace  of  soap  in  water  gives 
a  tint  of  blue.  London,  and  J  fear  Liverpool,  milk  makes 
an  approximation  to  the  same  color,  through  the  operation 
of  the  same  cause;  and  Helmholtz  has  irreverently  disclosed 
the  fact  that  the  deepest  blue  eye  is  simply  a  turbid 
medium. 

The  action  of  turbid  media  upon  light  was  illustrated 
by  Goethe,  who,  though  unacquainted  with  the  undulatory 
theory,  was  led  by  his  experiments  to  regard  the  firmament 
as  an  illuminated  turbid  medium,  with  the  darkness  of 
space  behind  it.  He  describes  glasses  showing  a  bright 
yellow  by  transmitted,  and  a  beautiful  blue  by  reflected, 
light.  Professor  Stokes,  who  was  probably  the  first  to 
discern  the  real  nature  of  the  action  of  small  particles  on 
the  waves  of  ether,  *  describes  a  glass  of  a  similar  kind,  f 
Capital  specimens  of  such  glass  are  to  be  found  at  Sal- 
viati's,  in  St.  James'  Street.  What  artists  call  "  chill " 
is  no  doubt  an  effect  of  this  description.  Through  the 
action  of  minute  particles,  the  browns  of  a  picture  often 
present  the  appearance  of  the  bloom  of  a  plum.  By  rub- 
bing the  varnish  with  a  silk  handkerchief  optical  continuity 

*  This  is  inferred  from  conversation.  I  am  not  aware  that  Pro- 
fessor Stokes  has  published  anything  upon  the  subject. 

f  This  glass,  by  reflected  light,  had  a  color  "strongly  resembling 
that  of  a  decoction  of  horse-chestnut  bark."  Curiously  enough, 
Goethe  refers  to  this  very  decoction:  "Man  nehtne  einen  Streifen 
frischer  Rinde  von  der  Rosskastanie,  man  stecke  denselben  in  ein 
Glas  Wasser,  und  in  der  kiirzesten  Zeit  werden  wir  das  vollkom- 
menste  Hiuiiuelblau  entstehen  sehen." — Goethe's  Werke,  B, 
p.  24- 


430  FRAGMENTS  OF  SCTENCK. 

is  established  and  the  chill  disappears.  Some  years  ago 
I  witnessed  Mr.  Hirst  experimenting  at  Zermatt  on  the 
turbid  water  of  the  Visp.  When  kept  still  for  a  day  or  so, 
the  grosser  matter  sank,  but  the  finer  particles  remained 
suspended,  and  gave  a  distinctly  blue  tinge  to  the  water. 
The  blueness  of  certain  Alpine  lakes  has  been  shown  to  be 
in  part  due  to  this  cause.  Professor  Roscoe  has  noticed 
several  striking  cases  of  a  similar  kind.  In  a  very  remark- 
able paper  the  late  Principal  Forbes  showed  that  steam 
issuing  from  the  safety-valve  of  a  locomotive,  when  favor- 
ably observed,  exhibits  at  a  gertain  stage  of  its  condensation 
the  colors  of  the  sky.  It  is  blue  by  reflected  light,  and 
orange  or  red  by  transmitted  light.  The  same  effect,  as 
pointed  out  by  Goethe,  is  to  some  extent  exhibited  by  peat- 
smoke.  More  than  ten  years  ago,  I  amused  myself  by 
observing,  on  a  calm  day  at  Killarney,  the  straight  smoke- 
columns  rising  from  the  cabin-chimneys.  It  was  easy  to 
project  the  lower  portion  of  a  column  against  a  dark  pine, 
and  its  upper  portion  against  a  bright  cloud.  The  smoke 
in  the  former  case  was  blue,  being  seen  mainly  by  reflected 
light;  in  the  latter  case  it  was  reddish,  being  seen  mainly 
by  transmitted  light.  Such  smoke  was  not  in  exactly  the 
condition  to  give  us  the  glow  of  the  Alps,  but  it  was  a  step 
in  this  direction.  Briicke's  fine  precipitate  above  referred 
to  looks  yellowish  by  transmitted  light;  but,  by  duly 
strengthening  the  precipitate,  you  may  render  the  white 
light  of  noon  as  ruby-colored  as  the  sun,  when  seen  through 
Liverpool  smoke,  or  upon  Alpine  horizons.  I  do  not,  how- 
ever, point  to  the  gross  smoke  arising  from  coal  as  an  illus- 
tration of  the  action  of  small  particles,  because  such  smoke 
soon  absorbs  and  destroys  the  waves  of  blue,  instead  of 
sending  them  to  the  eyes  of  the  observer. 

These  multifarious  facts,  and  numberless  others  which 
cannot  now  be  referred  to,  are  explained  by  reference  to 
the  single  principle,  that,  where  the  scattering  particles 
are  small  in  comparison  to  the  ethereal  waves,  we  have  in 
the  reflected  light  a  greater  proportion  of  the  smaller  waves, 
and  in  the  transmitted  light  a  greater  proportion  of  the 
larger  waves,  than  existed  in  the  original  white  light.  The 
consequence,  as  regards  sensation,  is  that  in  the  one  case 
blue  is  predominant,  and  in  the  other  orange  or  red.  Our 
best  microscopes  can  readily  reveal  objects  not  more  than 
one-fifty-thousandth  of  an  inch  in  diameter.  This  is  less. 


USE  OF  THE  IMAGINATION.  431 

than  the  length  of  a  wave  of  red  light.  Indeed  a  first-rate 
microscope  would  enable  us  to  discern  objects  not  exceed- 
ing in  diameter  the  length  of  the  smallest  waves  of  the 
visible  spectrum.*  By  the  microscope,  therefore,  we  can 
test  our  particles.  If  they  be  as  large  as  the  light-waves 
they  will  infallibly  be  seen;  and  if  they  be  not  so  seen,  it 
is  because  they  are  smaller.  Some  months  ago  I  placed  in 
the  hands  of  our  president  a  liquid  containing  Briicke's 
precipitate.  The  liquid  was  milky  blue,  and  Mr.  Huxley 
applied  to  it  his  highest  microscopic  power.  He  satisfied 
me  that  had  particles  of  even  one-one-hundred-thousandth  of 
au  inch  in  diameter  existed  in  the  liquid,  they  could  not 
have  escaped  detection.  But  no  particles  were  seen.  Un- 
der the  microscope  the  turbid  liquid  was  not  to  be  distin- 
guished from  distilled  water,  f 

But  we  have  it  in  our  power  to  imitate,  far  more  closely 
than  we  have  hitherto  done,  the  natural  conditions  of  this 
problem.  We  can  generate,  in  air,  artificial  skies,  and 
prove  their  perfect  identity  with  the  natural  one,  as  regards 
the  exhibition  of  a  number  of  wholly  unexpected  phenom- 
ena. By  a  continuous  process  of  growth,  moreover,  we 
are  able  to  connect  sky-matter,  if  I  may  use  the  term,  with 
molecular  matter  on  the  one  side,  and  with  molar  matter, 
or  matter  in  sensible  masses,  on  the  other.  In  illustration 
of  this,  I  will  take  an  experiment  suggested  by  some  of  my 
own  researches,  and  described  by  M.  Morren  of  Marseilles 
at  the  Exeter  meeting  of  the  British  Association.  Sulphur 
and  oxygen  combine  to  form  sulphurous  acid  gas,  two 
atoms  of  oxygen  and  one  of  sulphur  constituting  the  mole- 
cule of  sulphurous  acid.  It  has  been  recently  shown  that 
waves  of  ether  issuing  from  a  strong  source,  such  as  the 
sun  or  the  electric  light,  are  competent  to  shake  asunder 
the  atoms  of  gaseous  molecules.  J  A  chemist  would  call 
this,  "  decomposition  "  by  light;  but  it  behooves  us,  who 
are  examining  the  power  and  function  of  the  imagination, 

*  Dallinger  and  Drysdale  have  recently  measured  cilia  one-two- 
hundred-thousandth  of  an  inch  in  diameter.  1878. 

f  Like  Dr.  Burdon  Sanderson's  "  pyrogen,"  the  particles  of  mastic 
passed  without  sensible  hindrance,"  through  filtering- pa  per.  By 
such  filtering  no  freedom  from  suspended  particles  is  secured.  The 
application  of  a  condensed  beam  to  the  filtrate  renders  this  at  once 
evident. 

\  See  "  New  Chemical  Reactions  Produced  by  Light,"  vol.  i. 


432  FRAGMENTS  OF  SCIENCE. 

to  keep  constantly  before  us  the  physical  images  which 
underlie  our  terms.  Therefore  I  say,  sharply  and  defi- 
nitely, that  the  components  of  the  molecules  of  sulphurous 
acid  are  shaken  asunder  by  the  ether-waves.  Enclosing 
sulphurous  acid  in  a  suitable  vessel,  placing  it  in  a  dark 
room,  and  sending  through  it  a  powerful  beam  of  light,  we 
at  first  see  nothing:  the  vessel  containing  the  gas  seems  as 
empty  as  a  vacuum.  Soon,  however,  along  the  track  of  the 
beam  a  beautiful  sky-blue  color  is  observed,  which  is  due 
to  light  scattered  by  the  liberated  particles  of  sulphur. 
For -a  time  the  blue  grows  more  intense;  it  then  becomes 
whitish;  and  ends  in  a  more  or  less  perfect  white.  When 
the  action  is  continued  long  enough,  the  tube  is  filled  with 
a  dense  cloud  of  sulphur  particles,  which  by  the  application 
of  proper  means  may  be  rendered  individually  visible.* 

Here,  then,  our  ether-waves  untie  the  bond  of  chemical 
affinity,  and  liberate  a  body — sulphur — which  at  ordinary 
temperatures  is  a  solid,  and  which  therefore  soon  becomes 
an  object  of  the  senses.  We  have  first  of  all  the  free  atoms 
of  sulphur,  which  are  incompetent  to  stir  the  retina 
sensibly  with  scattered  light.  But  these  atoms  gradually 
coalesce  and  form  particles,  which  grow  larger  by  continual 
accretion,  until  after  a  minute  or  two  they  appear  as  sky- 
matter.  In  this  condition  they  are  individually  invisible; 
but  collectively  they  send  an  amount  of  wave-motion  to  the 
retina,  sufficient  to  produce  the  firmamental  blue.  The 
particles  continue,  or  may  be  caused  to  continue,  in  this 
condition  for  a  considerable  time,  during  which  no  micro- 
scope can  cope  with  them.  But  they  grow  slowly  larger, 
and  pass  by  insensible  gradations  into  the  state  of  cloud, 
when  they  can  no  longer  elude  the  armed  eye.  Thus, 
without  solution  of  continuity,  we  start  with  matter  in  the 
atom,  and  end  with  matter  in  the  mass;  sky-matter  being 
the  middle  term  of  the  series  of  transformations. 

Instead  of  sulphurous  acid,  we  might  choose  a  dozen 
other  substances,  and  produce  the  same  effect  with  all  of 
them.  In  the  case  of  some — probably  in  the  case  of  all — it 
is  possible  to  preserve  matter  in  the  firmamental  condition 

*  M.  Morren  was  mistaken  in  supposing  that  a  modicum  of  sulphur- 
ous acid,  in  the  drying  tubes,  bad  any  share  in  the  production  of  the 
"  actinic  clouds  "  described  by  me.  A  beautiful  case  of  molecular 
instability  in  tbe  presence  of  light  is  furnished  by  peroxide  of 
chlorine  as  proved  by  Professor  Dewar.  1878, 


USE  0 F  THE  IMA01NA TION.  433 

for  fifteen  or  twenty  minutes  under  the  continual  operation 
of  the  light.  During  these  fifteen  or  twenty  minutes  the 
particles  constantly  grow  larger,  without  ever  exceeding 
the  size  requisite  to  the  production  of  the  celestial  blue. 
Now  when  two  vessels  are  placed  before  us,  each  containing 
sky-matter,  it  is  possible  to  state  with  great  distinctness 
which  vessel  contains  the  largest  particles.  The  eye  is  very 
sensitive  to  differences  of  light,  when,  as  in  our  experi- 
ments, it  is  placed  in  comparative  darkness,  and  the  wave- 
motion  thrown  against  the  retina  is  small.  The  larger 
particles  declare  themselves  by  the  greater  whiteness  of 
their  scattered  light.  Call  now  to  mind  the  observation, 
or  effort  at  observation,  made  by  our  president,  when  he 
failed  to  distinguish  the  particles  of  mastic  in  Brucke's 
medium,  and  when  you  have  done  this,  please  follow  me. 
A  beam  of  light  is  permitted  to  act  upon  a  certain  vapor. 
In  two  minutes  the  azure  appears,  but  at  the  end  of  fifteen 
minutes  it  has  not  ceased  to  be  azure.  After  fifteen  min- 
utes its  color,  and  some  other  phenomena,  pronounce  it  to 
be  a  blue  of  distinctly  smaller  particles  than  those  sought 
for  in  vain  by  Mr.  Huxley.  These  particles,  as  already 
stated,  must  have  been  less  than  a  hundred  thousandth 
of  an  inch  in  diameter.  And  now  I  want  you  to  consider 
the  following  question:  Here  are  particles  which  have  been 
growing  continually  for  fifteen  minutes,  and  at  the  end  of 
that  time  are  demonstrably  smaller  than  those  which  defied 
the  microscope  of  Mr.  Huxley.  What  must  have  been  the 
size  of  these  particles  at  the  beginning  of  their  growth? 
What  notion  can  you  form  of  the  magnitude  of  such  par- 
ticles? The  distances  of  stellar  space  give  us  simply  a 
bewildering  sense  of  vastness,  without  leaving  any  distinct 
impression  on  the  mind;  and  the  magnitudes  with  which 
we  have  here  to  do  bewilder  us  equally  in  the  opposite 
direction.  We  are  dealing  with  infinitesimals,  compared 
with  which  the  test  objects  of  the  microscope  are  literally 
immense. 

Small  in  mass,  the  vastness  in  point  of  number  of  the 
particles  of  our  sky  may  be  inferred  from  the  continuity  of 
its  light.  It  is  not  in  broken  patches,  nor  at  scattered 
points,  that  the  heavenly  azure  is  revealed.  To  the 
observer  on  the  summit  of  Mont  Blanc,  the  blue  is  as  uni- 
form and  coherent  as  if  it  formed  the  surface  of  the  most 
close  grained  solid.  A  marble  dome  would  not  exhibit  a 


434  FRAGMENTS  OF  SCIENCK. 

stricter  continuity.  And  Mr.  Glaisher  will  inform  you, 
that  if  our  hypothetical  shell  were  lifted  to  twice  the 
height  of  Mont  Blanc  above  the  earth's  surface,  we  should 
still  have  the  azure  overhead.  By  day  this  light  quenches 
the  stars;  even  by  moonlight  it  is  able  to  exclude  from  vision 
all  stars  between  the  fifth  and  the  eleventh  magnitude.  It 
may  be  likened  to  a  noise,  and  the  feebler  stellar  radiance 
to  a  whisper  drowned  by  the  noise. 

What  is  the  nature  of  the  particles  which  shed  this 
light?  The  celebrated  De  la  Rive  ascribes  the  haze  of  the 
Alps  in  fine  weather  to  floating  organic  germs.  Now  the 
possible  existence  of  germs  in  such  profusion  has  been  held 
up  as  an  absurdity.  It  has  been  affirmed  that  they  would 
darken  the  air,  and  on  the  assumed  impossibility  of  their 
existence  in  the  requisite  numbers,  without  invasion  of  the 
solar  light,  an  apparently  powerful  argument  has  been 
based  by  believers  in  spontaneous  generation.  Similar 
arguments  have  been  used  by  the  opponents  of  the  germ 
theory  of  epidemic  disease,  who  have  triumphantly  chal- 
lenged an  appeal  to  the  microscope  and  the  chemist's  balance 
to  decide  the  question.  Such  arguments,  however,  are 
founded  on  a  defective  acquaintance  with  the  powers  and 
properties  of  matter.  Without  committing  myself  in  the 
least  to  De  la  Hive's  notion,  to  the  doctrine  of  spontaneous 
generation,  or  to  the  germ  theory  of  disease,  I  would 
simply  draw  attention  to  the  demonstrable  fact,  that,  in 
the  atmosphere  here,  we  have  particles  which  defy  both  the 
microscope  and  the  balance,  which  do  not  darken  the  air, 
and  which  exist,  nevertheless,  in  multitude  sufficient  to  re- 
duce to  insignificance  the  Israelitish  hyperbole  regarding 
the  sands  upon  the  seashore. 

The  varying  judgments  of  men  on  these  and  other 
questions  may  perhaps  be,  to  some  extent,  accounted  for 
by  that  doctrine  of  Relativity  which  plays  so  important  a 
part  in  philosophy.  This  doctrine  affirms  that  the  impres- 
sions made  upon  us  by  any  circumstance,  or  combination 
of  circumstances,  depend  upon  our  previous  state.  Two 
travelers  upon  the  same  height,  the  one  having  ascended 
to  it  from  the  plain,  the  other  having  descended  to  it  from 
a  higher  elevation,  will  be  differently  affected  by  the  scene 
around  them.  To  the  one  nature  is  expanding,  to  the 
other  it  is  contracting,  and  impressions  which  have  two 


VSB  OP  THE  IMAGINATION.  435 

such  different  antecedent  states  are  sure  to  differ.  In  our 
scientific  judgments  the  law  of  relativity  may  also  play 
an  important  part.  To  two  men,  one  educated  in  the 
school  of  the  senses,  having  mainly  occupied  himself  with 
observation;  the  other  educated  in  the  school  of  imagina- 
tion as  well,  and  exercised  in  the  conceptions  of  atoms 
and  molecules  to  which  we  have  so  frequently  referred, 
a  bit  of  matter,  say  one  fifty-thousandth  of  an  inch  in 
diameter,  will  present  itself  differently.  The  one  descends 
to  it  from  his  molar  heights,  the  other  climbs  to  it  from  his 
molecular  lowlands.  To  the  one  it  appears  small,  to  the 
other  large.  So,  also,  as  regards  the  appreciation  of  the 
most  minute  forms  of  life  revealed  by  the  microscope. 
To  one  of  the  men  these  naturally  appear  conterminous 
with  the  ultimate  particles  of  matter;  there  is  but  a  step 
from  the  atom  to  the  organism.  The  other  discerns  num- 
berless organic  gradations  between  both.  Compared  with  his 
atoms,  the  smallest  vibrios  and  bacteria  of  the  microscopic 
field  are  as  behemoth  and  leviathan.  The  law  of  relativity 
may  to  some  extent  explain  the  different  attitudes  of  two 
such  persons  with  regard  to  the  question  of  spontaneous 
generation.  An  amount  of  evidence  which  satisfies  the 
one  entirely  fails  to  satisfy  the  other:  and  while  to  the  one 
the  last  bold  defense  and  startling  expansion  of  the  doctrine 
by  Dr.  Bastian  will  appear  perfectly  conclusive,  to  the 
other  it  will  present  itself  as  merely  imposing  a  labor  of 
demolition  on  subsequent  investigators.* 

Let  me  say  here  that  many  of  our  physiological  observers 
appear  to  form  a  very  inadequate  estimate  of  the  distance 
which  separates  the  microscopic  from  the  molecular  limit, 
and  that  as  a  consequence,  they  sometimes  em  ploy  a  phrase- 
ology calculated  to  mislead.  When,  for  example,  the  con- 
tents of  a  cell  are  described  as  perfectly  homogeneous  or  as 
absolutely  structureless,  because  the  microscope  fails  to 
discover  any  structure;  or  when  two  structures  are  pro- 
nounced to  be  without  difference,  because  the  microscope 
can  discover  none,  then,  I  think  the  microscope  begins  to 
play  a  mischievous  part.  A  little  consideration  will  make 
it  plain  that  the  microscope  can  have  no  voice  in  the  ques- 
tion of  germ  structure.  Distilled  water  is  more  perfectly 

*When  these  words  were  uttered  I  did  not  imagine  that  the  chief 
labor  of  demolition  would  fall  upon  myself.  1878. 


436  tiu&MWito  ov  SCIENCE. 

homogeneous  than  any  possible  organic  germ.  What  is  it 
that  causes  the  liquid  to  cease  contracting  at  39  degrees 
Fahr.,  and  to  expand  until  it  freezes?  We  have  here  a 
structural  process  of  which  the  microscope  can  take  no 
note,  nor  is  it  likely  to  do  so  by  any  conceivable  extension 
of  its  powers.  Place  distilled  water  in  the  field  of  an 
electro-magnet,  and  bring  a  microscope  to  bear  upon  it. 
Will  any  change  be  observed  when  the  magnet  is  excited? 
Absolutely  none;  and  still  profound  and  complex  changes 
have  occurred.  First  of  all,  the  particles  of  water  have 
been  rendered  diamagnetically  polar;  and  secondly,  in 
virtue  of  the  structure  impressed  upon  it  by  the  magnetic 
whirl  of  its  molecules,  the  liquid  twists  a  ray  of  light  in  a 
fashion  perfectly  determinate  both  as  to  quantity  and 
direction. 

Have  the  diamond,  the  amethyst,  and  the  countless 
other  crystals  formed  in  the  laboratories  of  nature  and  of 
man  no  structure?  Assuredly  they  have;  but  what  can  the 
microscope  make  of  it?  Nothing.  It  cannot  be  too 
distinctly  borne  in  mind  that  between  the  microscopic 
limit,  and  the  true  molecular  limit,  there  is  room  for 
infinite  permutations  and  combinations.  It  is  in  this 
region  that  the  poles  of  the  atoms  are  arranged,  that  ten- 
dency is  given  to  their  powers;  so  that  when  these  poles 
and  powers  have  free  action,  proper  stimulus,  and  a  suitable 
environment,  they  determine,  first  the  germ,  and  after- 
ward the  complete  organism.  This  first  marshaling  of  the 
atoms,  on  which  all  subsequent  action  depends,  baffles  a 
keener  power  than  that  of  the  microscope.  When  duly 
pondered,  the  complexity  of  the  problem  raises  the  doubt, 
not  of  the  power  of  our  instrument,  for  that  is  nil,  but 
whether  we  ourselves  possess  the  intellectual  elements 
which  will  ever  enable  us  to  grapple  with  the  ultimate 
structural  energies  of  nature.* 

*  "  In  using  the  expression  'one  sort  of  living  substance'  I  must 
guard  against  being  supposed  to  mean  that  any  kind  of  living  proto- 
plasm is  homogeneous.  Hyaline  though  it  may  appear,  we  are  not  at 
present  able  to  assign  any  limit  to  its  complexity  of  structure." — 
Burdon  Sanderson,  in  the  "  British  Medical  Journal,"  January  16, 
1875. 

We  have  here  scientific  insight,  and  its  correlative  caution.  In  fact 
Dr.  Sanderson's  important  researches  are  a  continued  illustration  of 
the  position  laid  down  above. 


USE  OF  THE  IMAGINATION.  437 

In  more  senses  than  one  Mr.  Darwin  has  drawn  heavily 
upon  the  scientific  tolerance  of  his  age.  He  has  drawn 
heavily  upon  time  in  his  development  of  species,  and  he 
has  drawn  adventurously  upon  matter  in  his  theory  of  pan- 
genesis.  According  to  this  theory,  a  germ,  already  micro- 
scopic, is  a  world  of  minor  germs.  Not  only  is  the  organ- 
ism as  a  whole  wrapped  up  in  the  germ,  but  every  organ  of 
the  organism  has  there  its  special  seed.  This,  I  say,  is  an 
adventurous  draft  on  the  power  of  matter  to  divide  itself 
and  distribute  its  forces.  But,  unless  we  are  perfectly 
sure  that  he  is  overstepping  the  bounds  of  reason,  that  he 
is  unwittingly  sinning  against  observed  fact  or  demon- 
strated law — for  a  mind  like  that  of  Darwin  can  never  sin 
wittingly  against  either  fact  or  law — we  ought,  I  think,  to 
be  cautious  in  limiting  his  intellectual  horizon.  If  there 
be  the  least  doubt  in  the  matter,  it  ought  to  be  given  in 
favor  of  the  freedom  of  such  a  mind.  To  it  a  vast 
possibility  is  in  itself  a  dynamic  power,  though  the  pos- 
sibility may  never  be  drawn  upon.  It  gives  me  pleasure 
to  think  that  the  facts  and  reasonings  of  this  discourse 
tend  rather  toward  the  justification  of  Mr.  Darwin,  than 
toward  his  condemnation;  for  they  seem  to  show  the  per- 
fect competence  of  matter  and  force,  as  regards  divisibility 
and  distribution,  to  bear  the  heaviest  strain  that  he  has 
hitherto  imposed  upon  them. 

In  the  case  of  Mr.  Darwin,  observation,  imagination, 
and  reason  combined  have  run  back  with  wonderful 
sagacity  and  success  over  a  certain  length  of  the  line  of 
biological  succession.  Guided  by  analogy,  in  his  "  Origin 
of  Species  "  he  placed  at  the  root  of  life  a  primordial  germ, 
from  which  he  conceived  the  amazing  variety  of  the  or- 
ganisms now  upon  the  earth's  surface  might  be  deduced. 
If  this  hypothesis  were  even  true,  it  would  not  be  final. 
The  human  mind  would  infallibly  look  behind  the  germ, 
and  however  hopeless  the  attempt,  would  inquire  into  the 
history  of  its  genesis.  In  this  dim  twilight  of  conjecture 
the  searcher  welcomes  every  gleam,  and  seeks  to  augment 
his  light  by  indirect  incidences.  He  studies  the  methods 
of  nature  in  the  ages  and  the  worlds  within  his  reach,  in 
order  to  shape  the  course  of  speculation  in  antecedent  ages 
and  worlds.  And  though  the  certainty  possessed  by  experi- 
mental inquiry  ife  here  shut  out,  we  are  not  left  entirely 
without  guidance,  From  the  examination  of  the  solar 


438  FRAGMENTS  OF  SCIENCE. 

system,  Kant  and  Laplace  came  to  the  conclusion  that  its 
various  bodies  once  formed  parts  of  the  same  undislocated 
mass;  that  matter  in  a  nebulous  form  preceded  matter  in 
its  present  form;  that  as  the  ages  rolled  away,  heat  was 
wasted,  condensation  followed,  planets  were  detached; 
and  that  finally  the  chief  portion  of  the  hot  cloud 
reached,  by  self-compression,  the  magnitude  and  density 
of  our  sun.  The  earth  itself  offers  evidence  of  a  fiery 
origin;  and  in  our  day  the  hypothesis  of  Kant  and  Laplace 
receives  the  independent  countenance  of  spectrum  analysis, 
which  proves  the  same  substances  to  be  common  to  the 
earth  and  sun. 

Accepting  some  such  view  of  the  construction  of  our 
system  as  probable,  a  desire  immediately  arises  to  connect 
the  present  life  of  our  planet  with  the  past.  We  wish  to 
know  something  of  our  remotest  ancestry.  On  its  first 
detachment  from  the  central  mass,  life,  as  we  understand 
it,  could  not  have  been  present  on  the  earth.  How,  then, 
did  it  come  there?  The  thing  to  be  encouraged  here  is 
a  reverent  freedom — a  freedom  preceded  by  the  hard 
discipline  which  checks  licentiousness  in  speculation — 
while  the  thing  to  be  repressed,  both  in  science  and  out 
of  it,  is  dogmatism.  And  here  I  am  in  the  hands  of  the 
meeting — willing  to  end,  but  ready  to  go  on.  I  have  no 
right  to  intrude  upon  you,  unasked,  the  unformed 
notions  which  are  floating  like  clouds,  or  gathering  to 
more  solid  consistency,  in  the  modern  speculative  scientific 
mind.  But  if  you  wish  me  to  speak  plainly,  honestly,  and 
undisputatiously,  I  am  willing  to  do  so.  On  the  present 
occasion — 

You  are  ordained  to  call,  and  I  to  come. 

Well,  your  answer  is  given,  and  I  obey  your  call. 

Two  or  three  years  ago,  in  an  ancient  London  college,  I 
listened  to  a  discussion  at  the  end  of  a  lecture  by  a  very 
remarkable  man.  Three  or  four  hundred  clergymen  were 
present  at  the  lecture.  The  orator  began  with  the  civiliza- 
tion of  Egypt  in  the  time  of  Joseph;  pointing  out  the  very 
perfect  organization  of  the  kingdom,  and  the  possession  of 
chariots,  in  one  of  which  Joseph  rode,  as  proving  a  long 
antecedent  period  of  civilization.  He  then  passed  on  to 
the  mud  of  the  Nile,  its  rate  of  augmentation,  its  present 
thickness,  and  the  remains  of  human  handiwork  found 


USE  OF  THE  IMAGINATION.  439 

therein:  thence  to  the  rocks  which  bound  the  Nile  valley, 
and  which  teem  with  organic  remains.  Thus  in  his  own 
clear  way  he  caused  the  idea  of  the  world's  age  to  expand 
itself  indefinitely  before  tlie  minds  of  his  audience,  and 
he  contrasted  this  with  the  age  usually  assigned  to  the 
world.  During  his  discourse  he  seemed  to  be  swimming 
against  a  stream,  he  manifestly  thought  that  he  was  oppos- 
ing a  general  conviction.  He  expected  resistance  in  the 
subsequent  discussion;  so  did  I.  But  it  was  all  a  mistake; 
there  was  no  adverse  current,  no  opposing  conviction,  no 
resistance;  merely  here  and  there  a  half-humorous,  but 
unsuccessful  attempt  to  entangle  him  in  his  talk.  The 
meeting  agreed  with  all  that  had  been  said  regarding  the 
antiquity  of  the  earth  and  of  its  life.  They  had,  indeed, 
known  it  all  long  ago,  and  they  rallied  the  lecturer  for 
coming  among  them  with  so  stale  a  story.  It  was  quite 
plain  that  this  large  body  of  clergymen,  who  were,  I  should 
say,  to  be  ranked  among  the  finest  samples  of  their  class, 
had  entirely  given  up  the  ancient  landmarks,  and  trans- 
ported the  conception  of  life's  origin  to  an  indefinitely 
distant  past. 

This  leads  us  to  the  gist  of  our  present  inquiry,  which 
is  this:  Does  life  belong  to  what  we  call  matter,  or  is  it 
an  independent  principle  inserted  into  matter  at  some 
suitable  epoch — say  when  the  physical  conditions  became 
such  as  to  permit  of  the  development  of  life?  Let  us  put 
the  question  with  the  reverence  due  to  a  faith  and  culture 
in  which  we  all  were  cradled,  and  which  are  the  undeniable 
historic  antecedents  of  our  present  enlightenment.  I  say, 
let  us  put  the  question  reverently,  but  let  us  also  put  it 
clearly  and  definitely.  There  are  the  strongest  grounds 
for  believing  that  during  a  certain  period  of  its  history 
the  earth  was  not,  nor  was  it  fit  to  be,  the  theater  of  life. 
Whether  this  was  ever  a  nebulous  period,  or  merely  a  mol- 
ten period,  does  not  signify  much;  and  if  we  revert  to  the 
nebulous  condition,  it  is  because  the  probabilities  are 
really  on  its  side.  Our  question  is  this:  Did  creative 
energy  pause  until  the  nebulous  matter  had  condensed, 
until  the  earth  had  been  detached,  until  the  solar  fire  had 
sofar  withdrawn  from  the  earth's  vicinity  as  to  permit  a 
crust  to  gather  round  the  planet?  Did  it  wait  until  the 
air  was  isolated;  until  the  seas  were  formed;  until  evapora- 
tion, condensation  and  the  descent  of  rain  had  be- 


440  FRAGMENTS  OF  SCIENCE. 

gun;  until  the  eroding  forces  of  the  atmosphere  had 
weathered  and  decomposed  the  molten  rocks  so  as  to  form 
soils;  until  the  sun's  rays  had  become  so  tempered  by 
distance,  and  by  waste,  as  to  be  chemically  fit  for  the 
decompositions  necessary  to  vegetable  life?  Having 
waited  through  these  aeons  until  the  proper  conditions  had 
set  in,  did  it  send  the  fiat  forth,  "Let  there  be  Life?" 
These  questions  define  a  hypothesis  not  without  its  diffi- 
culties, but  the  dignity  of  which  in  relation  to  the  world's 
knowledge  was  demonstrated  by  the  nobleness  of  the  men 
whom  it  sustained. 

Modern  scientific  thought  is  called  upon  to  decide  be- 
tween this  hypothesis  and  another;  and  public  thought 
generally  will  afterward  be  called  upon  to  do  the  same. 
But,  however  the  convictions  of  individuals  here  and  there 
may  be  influenced,  the  process  must  be  slow  and  secular 
which  commends  the  hypothesis  of  Natural  Evolution  to 
the  public  mind.  For  what  are  the  core  and  essence  of 
this  hypothesis?  Strip  it  naked,  and  you  stand  face  to 
face  with  the  notion  that  not  alone  the  more  ignoble  forms 
of  animalcular  or  animal  life,  not  alone  the  nobler  forms 
of  the  horse  and  lion,  not  alone  the  exquisite  and  wonder- 
ful mechanism  of  the  human  body,  but  that  the  human 
mind  itself — emotion,  intellect,  will,  and  all  their  phe- 
nomena— were  once  latent  in  a  fiery  cloud.  Surely  the 
mere  statement  of  such  a  notion  is  more  than  a  refutation. 
But  the  hypothesis  would  probably  go  even  farther  than 
this.  Many  who  hold  it  would  probably  assent  to  the 
position  that,  at  the  present  moment,  all  our  philosophy, 
all  our' poetry,  all  our  science,  and  all  our  art — Plato, 
Shakspeare,  Newton,  and  llaphael — are  potential  in  the 
fires  of  the  sun.  We  long  to  learn  something  of  our  origin. 
If  the  Evolution  hypothesis  be  correct,  even  this  unsatis- 
fied yearning  must  have  come  to  us  across  the  ages  which 
separate  the  primeval  mist  from  the  consciousness  of  to-day. 
I  do  not  think  that  any  holder  of  the  Evolution  hypothesis 
would  say  that  I  overstate  or  overstrain  it  in  any  way.  I 
merely  strip  it  of  all  vagueness,  and  bring  before  you,  un- 
clothed and  unvarnished,  the  notions  by  which  it  must 
stand  or  fall. 

Surely  these  notions  represent  an  absurdity  too  mon- 
strous to  be  entertained  by  any  sane  mind.  But  why  are 
such  notions  absurd,  and  why  should  sanity  reject  them? 


USE  OF  THE  IMAGINATION.  441 

The  law  of  Relativity,  of  which  we  have  previously  spoken, 
may  find  its  application  here.  These  Evolution  notions 
are  absurd,  monstrous,  and  fit  only  for  the  intellectual 
gibbet,  in  relation  to  the  ideas  concerning  matter  which 
were  drilled  into  us  when  young.  Spirit  and  matter  have 
ever  been  presented  to  us  in  the  rudest  contrast,  the  one  as 
all-noble,  the  other  as  all-vile.  But  is  this  correct?  Upon 
the  answer  to  this  question  all  depends.  Supposing  that, 
instead  of  having  the  foregoing  antithesis  of  spirit  and 
matter  presented  to  our  youthful  minds,  we  had  been 
taught  to  regard  them  as  equally  worthy,  and  equally  won- 
derful; to  consider  them,  in  fact,  as  two  opposite  faces  of 
the  selfsame  mystery.  Supposing  that  in  youth  we  had 
been  impregnated  with  the  notion  of  the  poet  Goethe, 
instead  of  the  notion  of  the  poet  Young,  and  taught  to 
look  upon  matter,  not  as  "  brute  matter,"  but  as  the 
"  living  garment  of  God;"  do  you  not  think  that  under 
these  altered  circumstances  the  law  of  Relativity  might 
have  had  an  outcome  different  from  its  present  one?  Is  it 
not  probable  that  our  repugnance  to  the  idea  of  primeval 
union  between  spirit  and  matter  might  be  considerably 
abated?  Without  this  total  revolution  of  the  notions  now 
prevalent,  the  Evolution  hypothesis  muststand  condemned; 
but  in  many  profoundly  thoughtful  minds  such  a  revolution 
has  already  taken  place.  They  degrade  neither  member  of 
the  mysterious  duality  referred  to;  but  they  exalt  one  of 
them  from  its  abasement,  and  repeal  the  divorce  hitherto 
existing  between  them.  In  substance,  if  not  in  words, 
their  position  as  regards  the  relation  of  spirit  and  matter  is: 
"What  God  hath  joined  together,  let  not  man  put 
asunder." 

You  have  been  thus  led  to  the  outer  rim  of  speculative 
science,  for  beyond  the  nebulae  scientific  thought  has  never 
hitherto  ventured.  I  have  tried  to  state  that  which  I  con- 
sidered ought,  in  fairness,  to  be  outspoken.  I  neither 
think  this  Evolution  hypothesis  is  to  be  flouted  away  con- 
temptuously, nor  that  it  ought  to  be  denounced  as  wicked. 
It  is  to  be  brought  before  the  bar  of  disciplined  reason,  and 
there  justified  or  condemned.  Let  us  hearken  to  those  who 
wisely  support  it,  and  to  those  who  wisely  oppose  it;  and 
let  us  tolerate  those,  whose  name  is  legion,  who  try  fool- 
ishly to  do  either  of  these  things.  The  only  thing  out  of 
place  in  the  discussion  is  dogmatism  on  either  side.  Fear 


442  FRAGMENTS  OF  SCIENCE. 

not  the  Evolution  hypothesis.  Steady  yourselves,  in  its 
presence,  upon  that  faith  in  the  ultimate  triumph  of  truth 
which  was  expressed  by  old  Gamaliel  when  he  said:  "If  it 
be  of  God,  ye  cannot  overthrow  it;  if  it  be  of  man,  it  will 
come  to  naught."  Under  the  fierce  light  of  scientific 
inquiry,  it  is  sure  to  be  dissipated  if  it  possess  not  a  core  of 
truth.  Trust  me,  its  existence  as  a  hypothesis  is  quite 
compatible  with  the  simultaneous  existence  of  all  those 
virtues  to  which  the  term  "Christian"  has  been  applied. 
It  does  not  solve — it  does  not  profess  to  solve — the  ultimate 
mystery  of  this  universe.  Tt  leaves,  in  fact,  that  mystery 
untouched.  For,  granting  the  nebula  and  its  potential 
life,  the  question,  whence  they  came,  would  still  remain 
to  baffle  and  bewilder  us.  At  bottom,  the  hypothesis  does 
nothing  more  than  "  transport  the  conception  of  life's 
origin  to  an  indefinitely  distant  past." 

Those  who  hold  the  doctrine  of  Evolution  are  by  no 
means  ignorant  of  the  uncertainty  of  their  data,  and  they 
only  yield  to  it  a  provisional  assent.  They  regard  the 
nebular  hypothesis  as  probable,  and,  in  the  utter  absence  of 
any  evidence  to  prove  the  act  illegal,  they  extend  the 
method  of  nature  from  the  present  into  the  past.  Plere 
the  observed  uniformity  of  nature  is  their  only  guide. 
Within  the  long  range  of  physical  inquiry,  they  have  never 
discerned  in  nature  the  insertion  of  caprice.  Throughout 
this  range,  the  laws  of  physical  and  intellectual  continuity 
have  run  side  by  side.  Having  thus  determined  the 
elements  of  their  curve  in  a  world  of  observation  and 
experiment,  they  prolong  that  curve  into  an  antecedent 
world,  and  accept  as  probable  the  unbroken  sequence  of 
development  from  the  nebula  to  the  present  time.  You 
never  hear  the  really  philosophical  defenders  of  the  doctrine 
of  Uniformity  speaking  of  impossibilities  in  nature.  They 
never  say,  what  they  are  constantly  charged  with  saying, 
that  it  is  impossible  for  the  Builder  of  the  universe  to  alter 
His  work.  Their  business  is  not  with  the  possible,  but 
the  actual — not  with  a  world  which  might  be,  but  with  a 
world  that  is.  This  they  explore  with  a  courage  not 
unmixed  with  reverence,  and  according  to  methods  which, 
like  the  quality  of  a  tree,  are  tested  bv  their  fruits.  Thev 
have  but  one  desire — to  know  the  truth.  They  have  but 
one  fear — to  believe  a  lie.  And  if  they  know  the  strength 
of  science^  and  rely  upon  it  with  unswerving  trust,  they 


THE  B  EL  FA  ST  ADDRESS,  443 

also  know  the  limits  beyond  which  science  ceases  to  be 
strong.  They  best  know  that  questions  offer  themselves  to 
thought,  winch  science,  as  now  prosecuted,  has  not  even 
the  tendency  to  solve.  They  have  as  little  fellowship  with 
the  atheist  who  says  there  is  no  God,  as  with  the  theist 
who  professes  to  know  the  mind  of  God.  "  Two  things/* 
said  Immanuel  Kant,  "  fill  me  with  awe:  the  starry 
heavens  and  the  sense  of  moral  responsibility  in  man." 
And  in  his  hours  of  health  and  strength  and  sanity,  when 
the  stroke  of  action  has  ceased,  and  the  pause  of  reflection 
has  set  in,  the  scientific  investigator  finds  himself  over- 
shadowed by  the  same  awe.'  Breaking  contact  with  the 
hampering  details  of  earth,  it  associates  him  with  a  Power 
which  gives  fullness  and  tone  to  his  existence,  but  which 
he  can  neither  analyze  nor  comprehend'. 


CHAPTEfe  XXXI.  •'"'; 

THE   BELFAST   ADDRESS.*'"^''' 

There  is  one  God  supreme  over  all  gods,  diviner  than  mortals, 
Whose  form  is  not  like  unto  man's,  and  as  unlike  his  nature; 
But  vain  mortals  imagine  that  gods  like  themselves  are  begotten, 
With  human  sensations  and  voice  and  corporeal  members; 
So,  if  oxen  or  lions  had  hands  and  could  work  in  man's  fashion, 
And  trace  out  with  chisel  or  brush  their  conception  of  Godhead, 
Then  would  horses  depict  gods  like  horses,  and  oxen  like  oxen, 
Each  kind  the  divine  with  its  own  form  and  nature  endowing. 
XENOPHANES  of  COLOPHON  (six  centuries  B.  c.), 
Supernatural  Religion,  vol.  i.,  p.  76. 

SECTION  1.— An  impulse  inherent  in  primeval  man 
turned  his  thought's  and  questionings  betimes  toward  the 
sources  of  natural  phenomena.  The  same  impulse, 
inherited  and  intensified,  is  the  spur  of  scientific  action  to- 
day. Determined  by  it,  by  a  process  of  abstraction  from 
experience  we  form  physical  theories  which  lie  beyond  the 
pale  of  experience,  but  which  satisfy  the  desire  of  the  mind 
to  see  every  natural  occurrence  resting  upon  a  cause.  In 
forming  their  notions  of  the  origin  of  things,  our  earliest 
historic  (and  doubtless,  we  might  add,  our  prehistoric) 
ancestors  pursued,  as  far  as  their  intelligence  permitted, 

*  Delivered  before  the  British  Association  on  Wednesday  evening, 
August  19,  1874. 


444  FRAGMENTS  OF  SCIENCE. 

the  same  course.  They  also  fell  back  upon  experience; 
but  with  this  difference — that  the  particular  experiences 
which  furnished  the  warp  and  woof  of  their  theories  were 
drawn,  not  from  the  study  of  nature,  but  from  what  lay 
much  closer  to  them — the  observation  of  men.  Their 
theories  accordingly  took  an  anthropomorphic  form.  To 
supersensual  beings,  which,  (( however  potent  and  invisible, 
were  nothing  but  a  species  of  human  creatures,  perhaps 
raised  from  among  mankind,  and  retaining  all  human 
passions  and  appetites,"*  were  handed  over  the  rule  and 
governance  of  natural  phenomena. 

Tested  by  observation  and  reflection,  these  early  notions 
failed  in  the  long  run  to  satisfy  the  more  penetrating 
intellects  of  our  race.  Far  in  the  depths  of  history  we  find 
men  of  exceptional  power  differentiating  themselves  from 
the  crowd,  rejecting  these  anthropomorphic  notions,  and 
seeking  to  connect  natural  phenomena  with  their  physical 
principles.  '  But,  long  prior  to  these  purer  efforts  of  the 
understanding',  the  merchant  had  been  abroad,  and  rendered 
the  philosopher  possible;  commerce  had  been  developed, 
wealth  amassed,  leisure  for  travel  and  speculation  secured, 
while  races  educated  under  different  conditions,  and  there- 
fore differently  informed  and  endowed,  had  been  stimulated 
and  sharpened  by  mutual  contact.)  In  those  regions  where 
the  commercial  aristocracy  of  ancient  Greece  mingled  with 
their  eastern  neighbors,  the  sciences  were  born,  being 
nurtured  and  developed  by  free-thinking  and  courageous 
men.  The  state  of  things  to  be  displaced  may  be  gathered 
from  a  passage  of  Euripides  quoted  by  Hume.  "  There  is 
nothing  in  the  world;  no  glory,  no  prosperity.  The  gods 
;toss  all  into  confusion;  mix  everything  with  its  reverse, 
that  all  of  us,  from  our  ignorance  and  uncertainty,  may 
pay  them  the  more  worship  and  reverence."  Now  as 
science  demands  the  radical  extirpation  of  caprice,  and  the 
absolute  reliance  upon  law  in  nature,  there  grew  with  the 
growth  of  scientific  notions,  a  desire  and  determination  to 
sweep  from  the  field  of  theory  this  mob  of  gods  and  demons, 
and  to  place  natural  phenomena  on  a  basis  more  congruent 
with  themselves. 

The  problem  which  had  been  previously  approached 
from  above,  was  now  attacked  from  below;  theoretic  effort 

*Huine,  "  Natural  History  of  Religion.'1 


TEE  BELFAST  A  DDRES8,  445 

passed  from  the  super  to  the  sub-sensible.  It  was  felt 
that  to  construct  the  universe  in  idea,  it  was  necessary  to 
have  some  notion  of  its  constituent  parts — of  what 
Lucretius  subsequently  called  the  "  First  Beginnings." 
Abstracting  again  from  experience,  the  leaders  of  scientific 
speculation  reached  at  length  the  pregnant  doctrine  of 
atoms  and  molecules,  the  latest  developments  of  which 
were  set  forth  with  such  power  and  clearness  at  the  last 
meeting  of  the  British  Association.  Thought,  no  doubt, 
had  long  hovered  about  this  doctrine  before  it  attained  the 
precision  and  completeness  which  it  assumed  in  the  mind 
of  Democritus,*  a  philosopher  who  may  well  for  a  moment 
arrestte=our  attention.  "Few  great  men,"  says  Lange,  a 
non-materialist,  in  his  excellent  "  History  of  Materialism," 
to  the  spirit  and  to  the  letter  of  which  I  am  equally 
indebted,  "  have  been  so  despitefully  used  by  history  as 
Democritus.  In  the  distorted  images  sent  down  to  us 
through  unscientific  traditions,  there  remains  of  him 
almost  nothing  but  the  name  of  *  the  laughing  philoso- 
pher/ while  figures  of  immeasurably  smaller  significance 
spread  themselves  out  at  full  length  before  us."  Lauge 
speaks  of  Bacon's  high  appreciation  of  Democritus — for 
ample  illustrations  of  which  I  am  indebted  to  my  excellent 
friend  Mr.  Spedding,  the  learned  editor  and  biographer 
of  Bacon.  It  is  evident,  indeed,  that  Bacon  considered 
Democritus  to  be  a  man  of  weightier  metal  than  either 
Plato  or  Aristotle,  though  their  philosophy  "  was  noised 
and  celebrated  in  the  schools,  amid  the  din  and  pomp  of 
professors."  It  was  not  they ,[  but  Genseric  and  Attila  and 
the  barbarians,  who  destroyed  the  atomic  philosophy? 
"For,  at  a  time  when  all  human  learning  had  suffered 
shipwreck,  these  planks  of  Aristotelian  and  Platonic 
philosophy,  as  being  of  a  lighter  and  more  inflated  sub- 
stance, were  preserved  and  came  down  to  us,  while  things 
more  solid  sank  and  almost  passed  into  oblivion." 

The  son  of  a  wealthy  father,  Democritus  devoted  the 
whole  of  his  inherited  fortune  to  the  culture  of  his  mind. 
He  traveled  everywhere;  visited  Athens  when  [  Socrates 
and  Plato/were  there,  but  quitted  the  city  without  making 
himself  known.  Indeed,  the  dialectic  strife  in  which 
Socrates  so  much  delighted,  had  no  charm  for  Democritus, 

*  Born  460  B.  c. 


446  FRAGMENTS  OF  SCIENCE. 

who  held  that  "the  man  who  readily  contradicts,  and  uses 
many  words,  is  unfit  to  learn  anything  truly  right.''  He 
is  said  to  have  discovered  and  educated  Protagoras  the 
Sophist,  being  struck  as  much  by  the  manner  in  which 
he,  being  a  hewer  of  wood,  tied  np  his  faggots,  as  by  the 
sagacity  of  his  conversation.  Democritus  returned  poor 
from  his  travels,  was  supported  by  his  brother,  and  at 
length  wrote  his  great  work  entitled  "  Diakpsmos/'  which 
he  read  publicly  before  the  people  of  his  native  town.  He 
was  honored  by  his  countrymen  in  various  ways,  and  died 
serenely  at  a  great  age. 

'    The  principles  enunciated   by   Democritus   reveal    his 
uncompromising   antagonism    to   those    who  deduced   the 
phenomena  of  nature  from  the  caprices  of  the  gods.     They 
are  briefly  these:  1.    From  nothing  comes  nothing.     Noth- 
ing that  exists  can  be  destroyed.     All  changes  are  due  to 
the  combination  and  separation  of  molecules.     2.  Nothing 
\     happens  by  chance;  every  occurrence  has  its  cause,  from 
which  it  follows  by  necessity.     3.  The  only  existing  things 
\    are  the  atoms  and  empty  space;  all  else  is  mere  opinion. 
Y  4.  The  atoms  are  infinite  in  number  and  infinitely  various 
in  form;  they  strike  together,  and  the  lateral  motions  and 
i  whirlings  which  thus  arise  are  the  beginnings  of  worlds. 
I  5.  The  varieties  of  all  things  depend   upon  the  varieties  of 
I  their  atoms,  in  number,  size  and  aggregation.     6.  The  soul 
'  consists  of  fine,  smooth,  round  atoms,   like  those  of  fire. 
These  are  the  most  mobile  of  all:  they  interpenetrate  the 
whole  body,  and  in  their  motions  the  phenomena  of  life 
arise. 

The  first  five  propositions  are  a  fair  general  statement 
of  the  atomic  philosophy,  as  now  held.  As  regards  the 
sixth,  Democritus  made  his  finer  atoms  do  duty  for  the 
nervous  system,  whose  functions  were  then  unknown.  The 
atoms  of  Democritus  are  individually  without  sensation; 
they  combine  in  obedience  to  mechanical  laws;  and  not 
only  organic  forms,  but  the  phenomena  of  sensation  and 
thought,  are  the  result  of  their  combination. 

That  great  enigma,  "  the  exquisite  adaptation  of  one 
part  of  an  organism  to  another  part,  and  to  the  conditions 
of  life/'  more  especially  the  construction  of  the  human 
body,  Democritus  made  no  attempt  to  solve.  Empedocles, 
a  man  of  more  fiery  and  poetic  nature,  introduced  the 
notion  of  love  and  hate  among  the  atoms,  to  account  for 

^j,     .   .•„.  -  .  i         fa~#~' 


THE  BELFAST  ADDRESS.  44? 

their  combination  and  separation;  and  bolder  than  Dernoc* 
ritus,  he  struck  in  with  the  penetrating  thought,  linked, 
however,  with  some  wild  speculation,  that  it  lay  in  the  very 
nature  of  those  combinations  which  were  suited  to  their 
ends  (in  other  words,  in  harmony  with  their  environment) 
to  maintain  themselves,  while  unfit  combinations,  having 
no  proper  habitat,  must  rapidly  disappear.  /  Thus,  more 
than  two  thousand  years  ago,  the  doctrine  of  the  "survival  -^K^*^ 
of  the  fittest,"  which  in  our  day,  not  on  the  basis  of  vague 
conjecture,  but  of  positive  knowledge,  has  been  raised  to 
such  extraordinary  significance,  had  received  at  all  events 
partial  enunciation.*/'  -4^^.  "C 

Epicurus,t  said  to  be  the  son  of  a  poor  schoolmaster  at 
Samos,  is  the  next  dominant  figure  in  the  history  of  the 
atomic  philosophy.  He  mastered  the  writings  of  Democ- 
ritus,  heard  lectures  in  Athens,  went  buck  to  Samos,  and  .  , 
subsequently  wandered  through  various  countries.  He 
finally  returned  to  Athens,  where  he  bought  a  garden,  and 
surrounded  himself  by  pupils,  in  the  midst  of  whom  he 
lived  a  pure  and  serene  life,  and  died  a  peaceful  death. 
Democritus  looked  to  the  soul  as  the  ennobling  part  of 
man;  even  beauty,  without  understanding,  partook  of 
animalism.  Epicurus  also  rated  the  spirit  above  the  body; 
the  pleasure  of  the  body  being  that  of  the  moment,  while 
the  spirit  could  draw  upon  the  future  and  the  past.  His 
philosophy  was  almost  identical  with  that  of  Democritus; 
but  he  never  quoted  either  friend  or  foe.  One  main  object 
of  Epicurus  was  to  free  the  world  from  superstition  and 
the  fear  of  death.  Death  he  treated  with  indifference.  It 
merely  robs  us  of  sensation.  As  long  as  we  are,  death  is 
not;  and  when  death  is,  we  are  not.  Life  has  no  more 
evil  for  him  who  has  made  up  his  mind  that  it  is  no 
evil  not  to  live.  He  adored  the  gods,  but  not  in  the 
ordinary  fashion.  The  idea  of  divine  power,  properly 
purified,  he  thought  an  elevating  one.  Still  he  taught, 
"  Not  he  is  godless  who  rejects  the  gods  of  the  crowd,  but 
rather  he  who  accepts  them."  The  gods  were  to  him 
eternal  and  immortal  beings,  whose  blessedness  excluded 
every  thought  of  care  or  occupation  of  any  kind.  Nature 
pursues  her  course  in  accordance  with  everlasting  laws,  the 
gods  never  interfering.  They  haunt 

*  See  "Lange,"  2d  edit.,  p.  23.  f  Born  342  B.  c. 


448  FRAGMENTS  OF  SCIENCE. 

The  lucid  interspace  of  world  and  world 
Where  never  creeps  a  cloud  or  moves  a  wind, 
Nor  ever  falls  the  least  white  star  of  snow, 
Nor  ever  lowest  roll  of  thunder  moans, 
Nor  sound  of  human  sorrow  mounts  to  mar 
Their  sacred  everlasting  calm.* 

Lange  considers  the  relation  of  Epicurus  to  the  gods 
subjective;  the  indication,  probably,  of  an  ethical  require- 
ment of  his  own  nature.  We  cannot  read  history  with 
open  eyes,  or  study  human  nature  to  its  depths,  and  fail 
to  discern  such  a  requirement.  \  Man.  _never  has  been,  and 
he  never  will  be,  satisfied  with  the  operations  and  products 
of  the  understanding  alone;  hence  physical  science  cannot 
cover  all  the  demands  of  his  nature.  But  the  history  of 
the  efforts  made  to  satisfy  these  demands  might  be  broadly 
described  as  a  history  of  errors — the  error,  in  great  part, 
^  ^consisting  in  ascribing  fixity  to  that  which  is  fluent,  which 
varies  as  we  vary,  being  gross  when  we  are  gross,  and  be- 
coming, as  our  capacities  widen,  more  abstract  and  sublime. 
On  one  great  point  the  mind  of  Epicurus  was  at  peace. 
He  neither  sought  nor  expected,  here  or  hereafter,  any 
personal  profit  from  his  relation  to  the  gods.  And  it  is 
assuredly  a  fact,  that  loftiness  and  serenity  of  thought  may 
be  promoted  by  conceptions  which  involve  no  idea  of  profit 
of  this  kind.  "  Did  I  not  believe,"  said  a  great  man  f  to 
me  once,  "  that  an  Intelligence  is  at  the  heart  of  things, 
my  life  on  earth  would  be  intolerable."  The  utterer  of 
these  words  is  not,- in  my  opinion,  rendered  less,  but  more 
noble  by  the  fact  that  it  was  the  need  of  ethical  harmony 
here,  and  not  the  thought  of  personal  happiness  hereafter, 
that  prompted  his  observation. 

There  are  persons,  not  belonging  to  the  highest  intellec- 
tual zone,  nor  yet  to  the  lowest,  to  whom  perfect  clearness 
of  exposition  suggests  want  of  depth.  They  find  comfort 
and  edification  in  an  abstract  and  learned"  phraseology. 
To  such  people  Epicurus,  who  spared  no  pains  to  rid  his 
style  of  every  trace  of  haze  and  turbidity,  appeared,  on 
this  very  account,  superficial  He  had,  however,  a  disciple 
who  thought  it  no  unworthy  occupation  to  spend  his  days 
and  nights  in  the  effort  to  reach  the  clearness  of  his  master, 
and  to  whom  the  Greek  philosopher  is  mainly  indebted  for 

*  Tennyson's  "Lucretius."          fCarlyle. 

(i^4^^^r 

v     !  a 


. 

THE  BELFAST  ADDRKSS.  449 

the  extension  and  perpetuation  of  his  fame.  Some  two 
centuries  after  the  death  of  Epicurus,  Lucretius*  wrote  If 
his  great  poem,  "  On  the  Nature  of  Things,"  in  which  he, 
a  Roman,  developed  with  extraordinary  ardor  the  philos- 
ophy of  his  Greek  predecessor.  He  wishes  to  win  over 
his  friend  Memniusto  the  school  of  Epicurus;  and  although 
he  has  no  rewards  in  a  future  life  to  offer,  although  his 
object  appears  to  be  a  purely  negative  one,  he  addresses 
his  friend  with  the  heat  of  an  apostle.  His  object,  like 
that  of  his  great  forerunner,  is  the  destruction  of  supersti- 
tion; and  considering  that  men  in  his  day  trembled  before 
every  natural  event  as  a  direct  monition  from  the  gods, 
and  that  everlasting  torture  was  also  in  prospect,  the 
freedom  aimed  at  by  Lucretius  might  be  deemed  a  positive 
good.  "  This  terror,"  he  says,  "  and  darkness  of  mind, 
must  be  dispelled,  not  by  the  rays  of  the  sun  and  glittering 
shafts  of  day,  but  by  the  aspect  and  the  law  of  nature." 
He  refutes  the  notion  that  anything  can  come  out  of 
nothing,  or  that  what  is  once  begotten  can  be  recalled  to 
nothing.  The.  Jir&LJbegi nn ings,  the  atoms,  are  indestruct- 
ible, and  into  them  all  things  can  be  resolved  at  last. 
Bodies  are  partly  atoms  and  partly  combinations  of  atoms; 
but  the  atoms  nothing  can  quench.  They  are  strong  in 
solid  singleness,  and,  by  their  denser  combination,  all  things 
can  be  closely  packed  and  exhibit  enduring  strength.  He 
denies  that  matter  is  infinitely  divisible.  We  come  at 
length  to  the  atoms,  without  which,  as  an  imperishable 
substratum,  all  order  in  the  generation  and  development  of 
things  would  be  destroyed. 

The  mechanical  shock  of  the  atoms  being,  in  his  view, 
the  all-sufficient  cause  of  things,  he  combats  the  notion 
that  the  constitution  of  nature  has  been  in  any  way 
determined  by  intelligent  design.  The  interaction  of  the 
atoms  throughout  infinite  time  rendered  all  manner  of 
combinations  possible.  Of  these,  the  fit  ones  persisted,  ^ 
while  the  unfit  ones  disappeared.  Not  after  sage 
deliberation  did  the  atoms  station  themselves  in  their  right 
places,  nor  did  they  bargain  what  motions  they  should 
assume.  From  all  eternity  they  have  been  driven  together, 
and,  after  trying  motions  and  unions  of  every  kind,  they 
fell  at  length  into  the  arrangements  out  of  which  this 

*  Born  99  B.  c. 

••VM-' 


450  FRAGMENTS  OF  SCIENCE. 

system  of  things  has  been  evolved.  "  If  you  will  apprehend 
and  keep  in  mind  these  things,  Nature,  free  at  once,  and 
rid  of  her  haughty  lords,  is  seen  to  do  all  things  sponta- 
neously of  herself,  without  the  meddling  of  the  gods/'* 

To  meet  the  objection  that  his  atoms  cannot  be  seen, 
Lucretius  describes  a  violent  storm,  and  shows  that  the 
invisible  particles  of  air  act  in  the  same  way  as  the  visible 
particles  of  water.  We  perceive,  moreover,  the  different 
smells  of  things,  yet  never  see  them  coming  to  our  nostrils. 
Again,  clothes  hung  up  on  a  shore  which  waves  break  upon, 
become  moist,  and  then  get  dry  if  spread  out  in  the  sun, 
though  no  eye  can  see  either  the  approach  or  the  escape  of 
the  water-particles.  A  ring,  worn  long  on  the  finger, 
becomes  thinner;  a  water-drop  hollows  out  a  stone;  the 
plowshare  is  rubbed  away  in  the  field;  the  street-pavement 
is  worn  bv  the  feet;  but  the  particles  that  disappear  at  any 
moment  we  cannot  see.  Nature  acts  though  invisible  par- 
ticles. That  Lucretius  had  a  strong  scientific  imagination 
the  foregoing  references  prove.  A  fine  illustration  of  his 
power  in  this  respect,  is  his  explanation  of  the  apparent 
rest  of  bodies  whose  atoms  are  in  motion.  He  employs  the 
image  of  a  flock  of  sheep  with  skipping  lambs,  which,  seen 
from  a  distance,  presents  simply  a.  white  patch  upon  the 
green  hill,  the  jumping  of  the  individual  lambs  being 
quite  invisible. 

His  vaguely  grand  conception  of  the  atoms  falling 
eternally  through  space  suggested  the  nebular  hypothesis 
to  Kant,  its  first  propounder.  Far  beyond  the  limits  of 
our  visible  world  -are  to  be  found  atoms  innumerable, 
which  have  never  been  united  to  form  bodies,  or  which,  if 
once  united,  have  been  again  dispersed — falling  silently 
through  immeasurable  intervals  of  time  and  space.  As 
everywhere  throughout  the  All  the  same  conditions  are 
repeated,  so  must  the  phenomena  be  repeated  also.  Above 
us,  below  us,  beside  us,  therefore,  are  worlds  without  end; 
and  this,  when  considered,  must  dissipate  every  thought 
of  a  deflection  of  the  universe  by  the  gods.  The  worlds 
come  and  go,  attracting  new  atoms  out  of  limitless  space, 
or  dispersing  their  own  particles.  The  reputed  death  of 

*  Monro's  translation.  In  his  criticism  of  this  work  (Contemporary 
Review,  1867)  Dr.  Hay  man  does  not  appear  to  be  aware  of  the  really 
sound  and  subtile  observations  on  which  the  reasoning  of  Lucretius, 
though  erroneous,  sometimes  rests. 


THE  BELFAST  ADDRESS.  451 

Lucretius,  which  forms  the  basis  of  Mr.  Tennyson's  noble 
poem,  is  in  strict  accordance  with  his  philosophy,  which 
was  severe  and  pure. 

• 

SECTION  2. — Still  earlier  than  these  three  philosophers, 
and  during  the  centuries  between  tiie  first  of  them  and 
the  last,  the  human  intellect  was  active  in  other  fields  than 
theirs.  Pythagoras  had  founded  a  school  of  mathematics, 
and  made  his  experiments  on  the  harmonic  intervals.  The 
Sophists  had  run  through  their  'career.  At  Athens  had 
appeared  Socrates,  Plato,  and  Aristotle,  who  ruined  the . 
Sophists,  and  whose  yoke  remains  to  some  extent  unbroken 
to  the  present  hour.  Within  this  period  also  the  school 
of  Alexandria  was  founded,  Euclid  wrote  his  "Elements" 
and  made  some  advance  in  optics.  Archimedes  had  pro- 
pounded the  theory  of  the  lever,  and  the  principles  of 
hydrostatics.  Astronomy  was  immensely  enriched  by  the 
discoveries  of  Hipparchus,  who  was  followed  by  the  his- 
torically more  celebrated  Ptolemy.  Anatomy  had  been 
made  the  basis  of  scientific  medicine;  and  it  is  said  by 
Draper*  that  vivisection  had  begun.  In  fact,  the  science 
of  ancient  Greece  had  already  cleared  the  world  of  the 
fantastic  images  of  divinities  operating  capriciously 
through  natural  phenomena.  It  had  shaken  itself  free 
from  that  fruitless  scrutiny  "  by  the  internal  light  of 
the  mind  alone,"  which  had  vainly  sought  to  transcend 
experience,  and  to  reach  a  knowledge  of  ultimate  causes. 
Instead  of  accidental  observation,  it  had  introduced  obser- 
vation with  a  purpose;  instruments  were  employed  to 
aid  the  senses;  and  scientific  method  was  rendered  in  a 
great  measure  complete  by  che  union  of  Induction  and 
Experiment. 

What,  then,  stopped  its  victorious  advance?  Why  was 
the  scientific  intellect  compelled,  like  an  exhausted  soil,  to 
lie  fallow  for  nearly  two  millenniums,  before  it  could 
regather  the  elements  necessary  to  its  fertility  and  strength? 
Bacon  has  already  let  us  know  one  cause;  Whewell  ascribes 
this  stationary  period  to  four  causes— obscurity  of  thought, 
servility,  intolerance  of  disposition,  enthusiasm  of  temper; 
and  he  gives  striking  examples  of  each,  f  But  these  char- 

*-"  History  of  the  Intellectual  Development  of  Europe,"  p.  295. 
\  "  History  of  the  Indu,cti,ve  Sciences,"  vol.  i. 


452  FRAGMENTS  OF  SCIENCE. 

acteristics  must  have  had  their  antecedents  in  the  circum- 
stances of  the  time.  Koine,  and  the  other  cities  of  the 
empire,  had  fallen  into  moral  putrefaction.  Christianity 
had  appeared,  offering  the  Gospel  to  the  poor,  and  by 
moderation,  if  not  asceticism  of  life,  practically  protesting 
against  the  profligacy  of  the  age.  The  sufferings  of  the 
early  Christians,  and  the  extraordinary  exaltation  of  mind 
which  enabled  them  to  triumph  over  the  diabolical  tortures 
to  which  they  were  subjected,*  must  have  left  traces  not 
easily  effaced.  They  scorned  the  earth,  in  view  of  that 
"  building  of  God,  that  house  not  made  with  hands,  eternal 
in  the  heavens."  The  Scriptures  which  ministered  to 
their  spiritual  needs  were  also  the  measure  of  their  Science. 
When,  for  example,  the  celebrated  question  of  Antipodes 
cume  to  be  discussed,  the  Bible  was  with  many  the  ultimate 
court  of  appeal.  Augustine,  who  flourished  A.D.  400, 
would  not  deny  the  rotundity  of  the  earth;  but  he  would 
deny  the  possible  existence  of  inhabitants  at  the  other  side, 
"  because  no  such  race  is  recorded  in  Scripture  among  the 
descendants  of  Adam."  Archbishop  Boniface  was  shocked 
at  the  assumption  of  a  "  world  of  human  beings  out  of 
the  reach  of  the  means  of  salvation."  Thus  reined  in, 
Science  was  not  likely  to  make  much  progress.  Later  on, 
the  political  and  theological  strife  between  the  church  and 
civil  governments,  so  powerfully  depicted  by  Draper,  must 
have  done  much  to  stifle  investigation. 

Whewell  makes  many  wise  and  brave  remarks  regarding 
the  spirit"  of  the  middle  ages.  It  was  a  menial  spirit. 
The  seekers  after  natural  knowledge  had  forsaken  the 
fountain  of  living  waters,  the  direct  appeal  to  nature  by 
observation  and  experiment,  and  given  themselves  up  to 
the  remanipulation  of  the  notions  of  their  predecessors. 
It  was  a  time  when  thought  had  become  abject,  and  when 
the  acceptance  of  mere  authority  led,  as  it  always  does  in 
science,  to  intellectual  death.  Natural  events,  instead  of 
being  traced  to  physical,  were  referred  to  moral  causes; 
while  an  exercise  of  the  phantasy,  almost  as  degrading  as 
the  spiritualism  of  the  present  day,  took  the  place  of  scien- 
tific speculation.  Then  came  the  mysticism  of  the  middle 
ages,  magic,  alchemy,  the  Neoplatonic  philosophy,  with 
its  visionary  though  sublime  abstractions,  which  caused 

*  Described  with  terrible  vividness  iu  Kenan's  "Antichrist," 


THE  BELFAST  ADDRESS.  453 

men  to  look  with  shame  upon  their  own  bodies,  as  hin- 
drances to  the  absorption  of  the  creature  in  the  blessedness 
of  the  Creator.  Finally  came  the  scholastic  philosophy, 
a  fusion,  according  to  Lange,  of  tlfeT~l east  mature  notions 
of  Aristotle  with  the  Christianity  of  the  West.  Intel- 
lectual immobility  was  the  result.  ('  As  a  traveler  without 
a  compass  in  a  fog  may  wander  longrTmagining  he  is 
making  way,  and  find  himself  after  hours  of  toil  at  his 
starting-point,  §o^  the  schoolmen,  having  "tied  and  untied 
the  same  knots,  and  formed  and  dissipated  the  same 
clouds,"  *  found  themselves  at  the  end  of  centuries  in  their 
old  position.  | 

With  regard  to  the  influence  wielded  by  Aristotle  in  the 
middle  ages,  and  which,  to  a  less  extent,  he  still  wields,  I 
would  ask  permission  to  make  one  remark.  When  the 
human  mind  has  achieved  greatness  and  given  evidence  of 
extraordinary  power  in  one  domain,  there  is  a  tendency  to 
credit  it  with  similar  power  in  all  other  domains.  Thus 
theologians  have  found  comfort  and  assurance  in  the 
thought  that  Newton  dealt  with  the  question  of  revelation 
— forgetful  of  the  fact  that  the  very  devotion  of  his  powers, 
through  all  the  best  years  of  his  life,  to  a  totally  different 
class  of  ideas,  not  to  speak  of  any  natural  disqualification, 
tended  to  render  him  less,  instead  of  more  competent  to 
deal  with  theological  and  historic  questions.  Goethe, 
starting  from  his  established  greatness  as  a  poet,  and  indeed 
from  his  positive  discoveries  in  natural  history,  produced 
a  profound  impression  among  the  painters  of  Germany, 
when  he  published  his  "  Farbenlehre,"  in  which  he  en- 
deavored to  overthrow  Newton's  theory  of  colors.  This 
theory  he  deemed  so  obviously  absurd,  that  he  considered 
its  author  a  charlatan,  and  attacked  him  with  a  correspond- 
ing vehemence  of  language.  In  the  domain  of  natural 
history,  Goethe  had  made  really  considerable  discoveries; 
and  we  have  high  authority  for  assuming  that,  had  he 
devoted  himself  wholly  to  that  side  of  science,  he  might 
have  reached  an  eminence  comparable  with  that  which  he 
attained  as  a  poet.  In  sharpness  of  observation,  in  the 
detection  of  analogies  apparently  remote,  in  the  classifica- 
tion and  organization  of  facts  according  to  the  analogies 
discerned,  Goethe  possessed  extraordinary  powers.  These 


*  Whewell. 


454  FRAGMENTS  OF  SCIENCE. 

elements  of  scientific  inquiry  fall  in  with  the  disciplines  of 
the  poet.  But,  on  the  other  hand,  a  mind  thus  richly 
endowed  in  the  direction  of  natural  history  may  be  almost 
shorn  of  endowment  as  regards  the  physical  and  mechan- 
ical sciences.  Goethe  was  in  this  condition.  He  could 
not  formulate  distinct  mechanical  conceptions;  he  could 
not  see  the  force  of  mechanical  reasoning;  and  in  regions 
where  such  reasoning  reigns  supreme,  he  became  a  mere 
ignis  fatuus  to  those  who  followed  him. 

I  have  sometimes  permitted  myself  to  compare  Aristotle 
with  Goethe — to  credit  the  S_ta^mte_wrth_ an  almost  super- 
human power  of  amassing  and  systematizing  facts,  but  to 
consider  him  fatally  defective  on  that  side  of  the  mind,  in 
respect  to  which  incompleteness  has  been  just  ascribed  to 
Goethe.  Whewell  refers  the  errors  of  Aristotle  not  to  a 
neglect  of  facts,  but  to  "a  neglect  of  the  idea  appropriate 
to  the  facts;  the  idea  of  Mechanical  cause,  whicli  is  Force, 
and  the  substitution  of  vague  or  inapplicable  notions, 
involving  only  relations  of  space  or  emotions  of  wonder." 
This  is  doubtless  true;  but  the  word  "neglect"  implies 
mere  intellectual  misdirection,  whereas  in  Aristotle,  as 
in  Goethe,  it  was  not,  I  believe,  misdirection,  but  sheer 
natural  incapacity  which  lay  at  the  root  of  his  mistakes. 
As  a  physicist,  Aristotle  displayed  what  we  should  consider 
some  of  the  worst  of  attributes  in  a  modern  physical  inves- 
tigator— indistinctness  of  ideas,  confusion  of  mind,  and  a 
confident  use  of  language  which  led  to  the  delusive  notion 
that  he  had  really  mastered  his  subject,  while  he  had,  as 
yet,  failed  to  grasp  even  the  elements  of  it.  He  put  words 
in  the  place  of  things,  subject  in  the  place  of  object.  He 
preached  Induction  without  practicing  it,  inverting  the 
true  order  of  inquiry,  by  passing  from  the  general  to  the 
particular,  instead  of  from  the  particular  to  the  general. 
He  made  of  the  universe  a  closed  sphere,  in  the  center  of 
which  he  fixed  the  earth,  proving  from  general  principles, 
to  his  own  satisfaction  and  to  that  of  the  world  for  near 
two  thousand  years,  that  no  other  universe  was  possible. 
His  notions  of  motion  were  entirely  unphysical.  It  was 
natural  or  unnatural,  better  or  worse,  calm  or  violent — no 
real  mechanical  conception  regarding  it  lying  at  the  bottom 
of  his  mind.  He  affirmed  that  a  vacuum  could  not  exist, 
and  proved  that  if  it  did  motion  in  it  would  be  impossible. 
He  determined  a  priori  how  many  species  of  animals  must 


THE  BELFAST  ADD&ES&  455 

exist,  and  showed  on  general  principles  why  animals  must 
have  such  and  such  parts.  When  an  eminent  contemporary 
philosopher,  who  is  far  removed  from  errors  of  this  kind, 
remembers  these  abuses  of  the  a  jtriori  method,  lie  will  be 
able  to  make  allowance  for  the  jealousy  of  physicists  as  to 
the  acceptance  of  so-called  a  priori  truths.  Aristotle's 
errors  of  detail,  as  shown  by  Eucken  and  Lange,  were  grave 
and  numerous.  He  affirmed  that  only  in  man  we  had  the 
beating  of  the  heart,  that  the  left  side  of  the  body  was 
colder  than  the  right,  that  men  have  more  teeth  than 
women,  and  that  there  is  an  empty  space  at  the  back  of 
e v ery  maji!s Ji  ead . 

There  is  one  essential  quality  in  physical  conceptions, 
which  was  entirely  wanting  in  those  of  Aristotle  and  his 
followers — a  capability  of  being  placed  as  coherent  pictures 
before  the  mind.  The  Germans  express  the  act  of  picturing 
by  the  word  vorstellen,  and  the  picture  they  call  a  Vorstel- 
lung.  We  have  no  word  in  English  which  comes  nearerlo 
our  requirements  than  Imagination;  and,  taken  with  its 
proper  limitations,  the  word  answers  very  well.  But  it  is 
tainted  by  its  associations,  and  therefore  objectionable  to 
some  minds.  Compare,  with  reference  to  this  capacity  of 
mental  presentation,  the  case  of  the  Aristotelian,  who 
refers  the  ascent  of  water  in  a  pump  to  Nature's  abhorrence 
of  a  vacuum,  with  that  of  Pascal  when  he  proposed  to  solve 
the  question  of  atmospheric^  pressu re  by  the  ascent  of  the 
Puy  de  Dome.  In  the  one  case  the  terms  of  the  explanation 
refuse  to  fall  into  place  as  a  physical  image;  in  the  other  the 
image  is  distinct,  the  descent  and  rise  of  the  barometer 
being  clearly  figured  beforehand  as  the  balancing  of  two 
varying  and  opposing  pressures. 

SECTION  3. — During  the  drought  of  the  middle  ages  in 
Christendom,  the  Arabian  intellect,  as  forcibly  shown  by 
Draper,  was  active.  With  the  intrusion  of  the  Moors  into 
Spain,  order,  learning  and  refinement  took  the  place  of 
their  opposites.  When  smitten  with  disease,  the  Christian 
peasant  resorted  to  a  shrine,  the  Moorish  one  to  an 
instructed  physician.  The  Arabs  encouraged  translations 
from  the  Greek  philosophers,  but  not  from  the  Greek 
poets.  They  turned  in  disgust  "from  the  lewdness  of  our 
classical  mythology,  and  denounced  as  an  unpardonable 
blasphemy  all  connection  between  the  impure  Olympian 


456  FRAGMENTS  OF  SCIENCE. 

Jove  and  the  Most  High  God."  Draper  traces  still  further 
than  Whewell  the  Arab  elements  in  our  scientific  terms. 
He  gives  examples  of  what  Arabian  men  of  science  accom- 
plished, dwelling  particularly  on  A]hazen,  who  was  the 
first  to  correct  the  Platonic  notion  that  rays  of  light  are 
emitted  by  the  eye.  Alhazen  discovered  atmospheric 
refraction,  and  showed  that  we  see  the  snn  and  the  moon 
after  they  have  set.  He  explained  the  enlargement  of  the 
sun  and  moon,  and  the  shortening  of  the  vertical  diameters 
of  both  these  bodies  when  near  the  horizon.  He  was  aware 
that  the  atmosphere  decreases  in  density  with  increase  of 
elevation,  and  actually  fixed  its  height  at  fifty-eight  and 
one-half  miles.  In  the  "  Book  of  the  Balance  of  Wisdom/' 
he  sets  forth  the  connection  between  the  weight  of  the 
atmosphere  and  its  increasing  density.  He  shows  that  a 
body  will  weigh  differently  in  a  rare  and  dense  atmosphere, 
and  he  considers  the  force  with  which  plunged  bodies  rise 
through  heavier  media.  He  understood  the  doctrine  of 
the  center  of  gravity,  and  applied  it  to  the  investigation  of 
balances  and  steelyards.  He  recognized  gravity  as  a  force, 
though  he  fell  into  the  error  of  assuming  it  to  diminish 
simply  as  the  distance,  and  of  making  it  purely  terrestrial. 
He  knew  the  relation  between  the  velocities*,  spaces,  and 
times  of  falling  bodies,  and  had  distinct  ideas  of  capillary 
attraction.  He  improved  the  hydrometer.  The  determi- 
nations of  the  densities  of  bodies,  as  given  by  Alhazen, 
approach  very  closely  to  our  own.  "  I  join,"  says  Draper, 
"  in  the  pious  prayer  of  Alhazen,  that  in  the  day  of 
judgment  the  All-Merciful  will  take  pity  on  the  soul  of 
Abur-Raihan,  because  he  was  the  first  of  the  race  of  men  to 
construct  a  table  of  specific  gravities."  If  all  this  be  his- 
toric truth  (and  I  have  entire  confidence  in  Dr.  Draper), 
well  may  he  "deplore  the  systematic  manner  in  which  the 
literature  of  Europe  has  contrived  to  put  out  of  sight  our 
scientific  obligations  to  the  Mahommedans."  * 

The  strain  upon  the  mind  during  the  stationary  period 
toward  ultra-terrestrial  things,  to  the  neglect  of  problems 
close  at  hand,  was  sure  to  provoke  reaction.  But  the 
reaction  was  gradual;  for  the  ground  was  dangerous,  and  a 
power  was  at  hand  competent  to  crush  the  critic  who  went 
too  far.  To  elude  this  power,  and  still  allow  opportunity 

*"  Intellectual  Development  of  Europe,"  p.  359 


.  - 


THE  BELFAST  ADDRESS.  457 

for  the  expression  of  opinion,  the  doctrine  of  "  twofold 
truth"  was  invented,  according  to  which  an  opinion  might 
be  held  "  theologically,"  and  the  opposite  opinion  "  philo- 
sophically." *  Thus,  in  the  thirteenth  century,  the  creation 
of  the  world  in  six  days,  and  the  unchangeableness  of  the 
individual  soul,  which  had  been  so  distinctly  affirmed  by 
St.  Thomas  Aquinas,  were  both  denied  philosophically,  but 
admitted  to  be  true  as  articles  of  the  Catholic  faith.  When 
Protagoras  uttered  the  maxim  which  brought  upon  him  so 
much  vituperation,  that  "opposite  assertions  are  equally 
true,"  he  simply  meant  to  affirm  men's  differences  to  be  so 
great,  that  what  was  subjectively  true  to  the  one  might  be 
subjectively  untrue  to  the  other.  The  great  Sophist  never 
meant  to  play  fast  and  loose  with  the  truth  by  saying  that 
one  of  two  opposite  assertions,  made  by  the  same  individual, 
could  possibly  escape  being  a  lie.  It  was  not  "sophistry," 
but  the  dread  of  theologic  vengeance,  that  generated  this 
double  dealing  with  conviction;  and  it  is  astonishing  to 
notice  what  lengths  were  allowed  to  men  who  were  adroit 
in  the  use  of  artifices  of  this  kind. 

Toward  the  close  of  the  stationary  period  a  word-wea_ri- 
ness,  if  I  may  so  express  it,  took  more  and  more  possession 
of  men's  minds.  Christendom  had  become  sick  of  the 
School  Philosophy  and  its  verbal  wastes,  which  led  to  no 
issue,  but  left  the  intellect  in  everlasting  haze.  Here  and 
there  was  heard  the  voice  of  one  impatiently  crying  in  the 
wilderness,  "Not  unto  Aristotle,  not  unto  subtle  hypoth- 
esis, not  unto  church,  Bible,  or  blind  tradition,  must  we 
turn  for  a  knowledge  of  the  universe,  but  to  the  direct 
investigation  of  nature  by  observation  and  experiment." 
In  1543  the  epoch-marking  work  of  Copernicus  on  the 
paths  of  the  heavenly  bodies  appeared.  The  total  crash  of 
Aristotle's  closed  universe,  with  the  earth  at  its  center, 
followed  as  a  consequence,  and  "The  earth  moves!"  be- 
came a  kind  of  watchword  among  intellectual  freemen. 
Copernicus  was  canon  of  the  church  of  Frauenburg  in  the 
diocese  of  Ermeland.  For  three-and-thirty  years  he  had 
withdrawn  himself  from  the  world,  and  devoted  himself  to 
the  consolidation  of  his  great  scheme  of  the  solar  system. 
He  made  its  blocks  eternal;  and  even  to  those  who  feared 
it,  and  desired  its  overthrow,  it  was  so  obviously  strong, 

*  "Lange,"  2nd  ed.  pp.  181,  182. 


458  FRAGMENTS  OF  SCIENCE. 

that  they  refrained  for  a  time  from  meddling  with  it.  In 
the  last  year  of  the  life  of  Copernicus  his  book  appeared: 
it  is  said  that  the  old  man  received  a  copy  of  it  a  few  days 
before  his  death,  and  then  departed  in  pence. 

The  Italian  philosopher,  Giordano  Bruno,  was  one  of 
the  earliest  converts  to  the  new  astronomy.  Taking 
Lucretius  as  his  exemplar,  he  revived  the  notion  of  the 
infinity  of  worlds;  and,  combining  with  it  the  doctrine  of 
Copernicus,  reached  the  sublime  generalization  that  the 
fixed  stars  are  suns,  scattered  numberless  through  space, 
and  accompanied  by  satellites,  which  bear  the  same  relation 
to  them  that  our  earth  does  to  our  sun,  or  our  moon  to  our 
earth.  This  was  an  expansion  of  transcendent  import; 
but  Bruno  came  closer  than  this  to  our  present  line  of 
thought.  Struck  with  the  problem  of  the  generation  and 
maintenance  of  organisms,  and  duly  pondering  it,  he  came 
to  the  conclusion  that  Nature,  in  her  productions,  does  not 
imitate  the  technic  of  man.  Her  process  is  one  of  un- 
raveling and  unfolding.  The  infinity  of  forms  under 
which  matter  appears  was  not  imposed  upon  it  by  an  ex- 
ternal artificer;  by  its  own  intrinsic  force  and  virtue  it 
brings  these  forms  forth.  Matter  is  not  the  mere  naked, 
empty  capacity  which  philosophers  have  pictured  her  to  be, 
but  the  universal  mother,  who  brings  forth  all  things  as 
the  fruit  of  her  own  womb. 

This  outspoken  man  was  originally  a  Dominican  monk. 
He  was  accused  of  heresy  and  had  to  fly,  seeking  refuge  in 
Geneva,  Paris,  England,  and  Germany.  In  1592  he  fell 
into  the  hands  of  the  Inquisition  at  Venice.  He  was  im- 
prisoned for  many  years,  tried,  degraded,  excommunicated, 
and  handed  over  to  the  civil  power,  with  the  request  that 
he  should  be  treated  gently,  and  "  without  the  shedding  of 
blood."  This  meant  that  he  was  to  be  burnt;  and  burnt 
accordingly  he  was,  on  February  16,  1600.  To  escape  a 
similar  fate  jG.alil.eo,  thirty-three  years  afterward,  abjured 
upon  his  knees,  with  his  hands  upon  the  holy  Gospels,  the 
heliocentric  doctrine,  which  he  knew  to  be  true.  After 
Galileo  came  Kepler,  who  from  his  German  home  defied 
the  ultramontane  power.  He  traced  out  from  pre-existing 
observations  the  laws  of  planetary  motion.  Materials  were 
thus  prepared  for  Newton,  who  bound  those  empirical  laws 
together  by  the  principle  of  gravitation. 


THE  SHLVASl  ADDRESS.  459 

SECTION  4. — In  the  seventeenth  century  Bacon  and 
Descartes,  the  restorers  of  philosophy,  appeared  in  snces- 
sion.  Differently  educated  and  endowed,  their  philosophic 
tendencies  were  different.  Bacon  held  fast  to  Induction, 
believing  firmly  in  the  existence  of  an  external  world,  and 
making  collected  experiences  the  basis  of  all  knowledge. 
The  mathematical  studies  of  Descartes  gave  him  a  bias 
toward  deduction;  and  his  fundamental  principle  was 
much  the  same  as  that  of  Protagoras,  who  made  the  indi- 
vidual man  the  measure  of  all  things.  "  I  think,  therefore 
I  am,"  said  Descartes.  Only  his  own  identity  was  sure  to 
him;  and  the  full  development  of  this  system  would  have 
led  to  an  idealism,  in  which  the  outer  world  would  have 
been  resolved  into  a  mere  phenomenon  of  consciousness. 
GLassendi,  one  of  Descartes'  contemporaries,  of  whom  we 
shall  hear  more  presently,  quickly  pointed  out  that  the 
fact  of  personal  existence  would  be  proved  as  well  by  refer- 
ence to  any  other  act,  as  to  the  act  of  thinking.  I  eat, 
therefore  I  am,  or  I  love,  therefore  I  am,  would  be  quite  as 
conclusive.  Lichtenberg,  indeed,  showed  that  the  very 
thing  to  be  proved  was  inevitably  postulated  in  the  first 
two  words,  "I  think;"  and  it  is  plain  that  no  inference 
from  the  postulate  could,  by  any  possibility,  be  stronger 
than  the  postulate  itself. 

But  Descartes  deviated  strangely  from  the  idealism  im- 
plied in  his  fundamental  principle.  He  was  the  first  to 
reduce,  in  a  manner  eminently  capable  of  bearing  the  test 
of  mental  presentation,  vital  phenomena  to  purely  mechan- 
ical principles.  Through  fear  or  love,  Descartes  was  a 
good  churchman;  he  accordingly  rejected  the  notion  of  an 
atom,  because  it  was  absurd  to  suppose  that  God,  if  He  so 
pleased,  could  not  divide  an  atom;  he  puts  in  the  place  of 
the  atoms  small  round  particles,  and  light  splinters,  out  of 
which  he  builds  the  organism.  He  sketches  with  marvel- 
ous physical  insight  a  machine,  with  water  for  its  motive 
power,  which  shall  illustrate  vital  actions.  He  has  made 
clear  to  his  mind  that  such  a  machine  would  be  competent 
to  carry  on  the  processes  of  digestion,  nutrition,  growth, 
respiration,  and  the  beating  of  the  heart.  It  would  be 
competent  to  accept  impressions  from  the  external  sense, 
to  store  them  up  in  imagination  and  memory,  to  go  through 
the  internal  movements  of  the  appetites  and  passions,  and 
the  external  movements  of  the  limbs.  He  deduces  these 


460  FRAGMENTS  OF  SCIENCE. 

functions  of  his  machine  from  the  mere  arrangements  of 
its  organs,  as  the  movement  of  a  clock,  or  other  automaton, 
is  deduced  from  its  weights  and  wheels.  "  As  far  as  these 
functions  are  concerned,"  he  says,  "it  is  not  necessary  to 
conceive  any  other  vegetative  or  sensitive  soul,  nor  any 
other  principle  of  motion  or  of  life,  than  the  blood  and 
the  spirits  agitated  by  the  fire  which  burns  continually  in 
the  heart,  and  which  is  in  nowise  different  from  the  fires 
existing  in  inanimate  bodies.*'  Had  Descartes  been 
acquainted  with  the  steam-engine,  he  would  have  taken  it, 
instead  of  a  fall  of  water,  as  his  motive  power.  He  would 
have  shown  the  perfect  analogy  which  exists  between  the 
oxidation  of  the  food  in  the  body,  and  that  of  the  coal  in 
the  furnace.  He  would  assuredly  have  anticipated  Mayer 
in  calling  the  blood  which  the  heart  diffuses,  "the  oil  of 
the  lamp  of  life,"  deducing  all  animal  motions  from  the 
combustion  of  this  oil,  as  the  motions  of  a  steam-engine 
are  deduced  from  the  combustion  of  its  coal.  As  the 
matter  stands,  however,  and  considering  the  circum- 
stances of  the  time,  the  boldness,  clearness,  and  precision, 
with  which  Descartes  grasped  the  problem  of  vital  dynam- 
ics constitute  a  marvelous  illustration  of  intellectual 
power.* 

During  the  middle  ages  the  doctrine  of  atoms  had  to  all 
appearance  vanished  from  discussion.  It  probably  held  its 
ground  among  sober-minded  and  thoughtful  men,  though 
neither  the  church  nor  the  world  was  prepared  to  hear  of 
it  with  tolerance.  Once,  in  the  year  1348,  it  received 
distinct  expression.  But  retractation  by  compulsion  im- 
mediately followed;  and,  thus  discouraged,  it  slumbered 
till  the  seventeenth  century,  when  it  was  revived  by  a 
contemporary  and  friend  of  Hobbes  of  Malmesbury,  the 
orthodox  Catholic  provost  of  Digne,  Gassendi.  But, 
before  stating  his  relation  to  the  Epicurean  doctrine,  it 
will  be  well  to  say  a  few  words  on  the  effect,  as  regards 
science,  of  the  general  introduction  of  monotheism  among 
European  nations. 

"Were  men,"  says  Hume,  "  led  into  the  apprehension 
of  invisible  intelligent  power  by  contemplation  of  the 
works  of  Nature,  they  could  nev,er  possibly  entertain  any 

*See  Huxley's  admirable  "Essay  on  Descartes."  "  Lay  Sermons," 
pp.  364,  365. 


THE  BELFAST  ADDRESS.  461 

conception  but  of  one  single  Being,  who  bestowed  existence 
und  order  on  this  vast  machine,  and  adjusted  all  its  parts 
to  one  regular  system."  Referring  to  the  condition  of  the 
heathen,  who  sees  a  god  behind  every  natural  event,  thus 
peopling  the  world  with  thousands  of  beings  whosecaprices 
are  incalculable,  Lange  shows  the  impossibility  of  any 
compromise  between  snch  notions  and  those  of  science, 
which  proceeds  on  the  assumption  of  never-changing  law 
and  causality.  "But,"  he  continues,  with  characteristic 
penetration,  "when  the  great  thought  of  one  God,  acting 
as  a  unit  npon  the  universe,  has  been  seized,  the  connection 
of  things  in  accordance  with  the  law  of  cause  and  effect  is 
not  only  thinkable,  but  it  is  a  necessary  consequence  of  the 
assumption.  For  when  I  see  ten  thousand  wheels  in 
motion,  and  know,  or  believe,  that  they  are  all  driven  by 
one  motive  power,  then  I  know  that  1  have  before  me  a 
mechanism,  the  action  of  every  part  of  which  is  determined 
by  the  plan  of  the  whole.  So  much  being  assumed,  it 
follows  that  I  may  investigate  the  structure  of  that  machine, 
and  the  various  motions  of  its  parts.  For  the  time  being, 
therefore,  this  conception  renders  scientific  action  free." 
In  other  words,  were  a  capricious  God  at  the  circumference 
of  every  wheel  and  at  the  end  of  every  lever,  the  action  of 
the  machine  would  be  incalculable  by  the  methods  of 
science.  But  the  actions  of  all  its  parts  being  rigidly 
determined  by  their  connections  and  relations,  and  these 
being  brought  into  play  by  a  single  motive  power, 
then  though  this  last  prime  mover  may  elude  me,  I  am 
still  able  to  comprehend  the  machinery  which  it  sets  in 
motion.  We  have  here  a  conception  of  the  relation  of 
Nature  to  its  Author,  which  seems  perfectly  acceptable  to 
some  minds,  but  perfectly  intolerable  to  others.  Newton 
and  Boyle  lived  and  worked  happily  under  the  influence 
of  this  conception;  Goethe  rejected  it  with  vehemence, 
and  the  same  repugnance  to  accepting  it  is  manifest  in 
Carlyle.* 

The  analytic_and   synthetic   tendencies  of  the  human 

*  Boyle's  model  of  the  universe  was  the  Strasburg  clock  with  an 
outside  Artificer.     Goethe,  on  the  other  hand,  sang 

"  linn  ziemt's  die  Welt  im  Innern  zu  bewegen,xV/U"'"t-^  ^ 

JXatur  in  sich,  sich  in  Natur  zu  hegen." 
See  also  Carlyle,  "  Past  and  Present,"  cliap.  v. 


462  FRAGMENTS  OF  SCIENCE. 

mind  are  traceable  throughout  history,  great  writers  ranging 
themselves  sometimes  on  the  one  side,  sometimes  on  the 
obher^TMen  of  warm  feelings,  and  minds  open  to  the 
elevating  impressions  produced  by  nature  as  a  whole,  whose 
satisfaction,  therefore,  is  rather  ethical  than  logical,  lean 
to  the  synthetic  side;  while  the  analytic  harmonizes  best 
with  the  more  precise  and  more  mechanical  .bias  which 
seeks  the  satisfaction  of  the  understanding.  -A' Some  form 
of  pantheism  was  usually  adopted  by  the  one,  while  a 
detached  Creator,  working  more  or  less  after  the  manner 
of  men,  was  often  assumed  by  the  other.  Gasseudi,  as 
sketched  by  Lange,  is  hardly  to  be  ranked  with  either. 
Having  formally  acknowledged  God  as  the  great  first  cause, 
he  immediately  dropped  the  idea,  applied  the  known  laws 
of  mechanics  to  the  atoms,  and  deduced  from  them  all  vital 
phenomena.  He  defended  Epicurus,  and  dwelt  upon  his 
purity,  both  of  doctrine  and  of  life.  True,  he  was  a 
heathen,  but  so  was  Aristotle.  Epicurus  assailed  super- 
stition and  religion,  and  rightly,  because  he  did  not  know 
the  true  religion.  He  thought  that  the  gods  neither 
rewarded  nor  punished,  and  he  adored  them  purely  in  con- 
sequence of  their  completeness:  here  we  see,  says  Gassendi, 
the  reverence  of  the  child,  instead  of  the  fear  of  the  slave. 
The  errors  of  Epicurus  shall  be  corrected,  and  the  body  of 
his  truth  retained.  Gassendi  then  proceeds,  as  any  heathen 
might  have  done,  to  build  up  the  world,  and  all  that 
therein  is,  of  atoms  and  molecules.  God,  who  created 
earth  and  water,  plants  and  animals,  produced  in  the  first 
place  a  definite  number  of  atoms,  which  constituted  the 
seed  of  all  things.  Then  began  that  series  of  combinations 
and  decompositions  which  now  goes  on,  and  which  will 
continue  in  future.  The  principle  of  every  change  resides 
in  matter.  In. artificial  productions  the  moving  principle 
is  different  from  the  material  worked  upon;  Tnit  in  nature 
the  agent  works  within,  being  the  most  active  and  mobile 
part  of  the  material  itself.  Thus  this  bold  ecclesiastic, 
without  incurring  the  censure  of  the  church  or  the  world, 
contrives  to  outstrip  Mr.  Darwin.  The  same  cast  of  mind 
which  caused  him  to  detach  the  Creator  from  his  universe 
led  him  also  to  detach  the  soul  from  the  body,  though  to 
the  body  he  ascribes  an  influence  so  large  as  to  render  the 
soul  almost  unnecessary.  The  aberrations  of  reason  were, 
in  his  view,  an  affair  of  the  material  brain.  Mental  disease 


THE  BELFAST  ADDRESS.  463 

is  bruin-disease;  but  then  the  immortal  reason  sits  apart, 
and  cannot  be  touched  by  the  disease.  The  errors  of  mad- 
ness are  those  of  the  instrument,  not  of  the  performer. 

It  may  be  more  than  a  mere  result  of  education,  con- 
necting itself,  probably,  with  the  deeper  mental  structure 
of  the  two  men,  that  the  idea  of  Gasseudi,  above  enunciated, 
is  substantially  the  same  as  that  expressed  by  Professor 
Clerk  Maxwell,  at  the  close  of  the  very  able  lecture  deliv- 
ered by  him  at  Bradford  in  1873.  According  to  both  phi- 
losophers, the  atoms,  if  I  understand  aright,  are  prepared 
materials,  which,  formed  once  for  all  by  the  Ete"riial,  pro- 
duce by  their  subsequent  interaction  all  the  phenomena  of 
the  material  world.  There  seems  to  be  this  difference, 
however,  between  Gassendi  and  Maxwell.  The  Q\\Q  postu- 
lates, the  other  infers  his  first  cause.  In  his  "  manu- 
factured articles,"  as  he  calls  the  atoms,  Professor  Maxwell 
finds  the  basis  of  an  induction,  which  enables  him  to  scale 
philosophic  heights  considered  inaccessible  by  Kant,  and 
to  take  the  logical  step  from  the  atoms  to  their  Maker. 

Accepting  here  the  leadership  of  Kant,  I  doubt  the 
legitimacy  of  Maxwell's  logic;  but  it  is  impossible  not  to 
feel  the  ethic  glow  with  which  his  lecture  concludes. 
There  is,  moreover,  a  very  noble  strain  of  eloquence  in  his 
description  of  the  steadfastness  of  the  atoms:  "Natural 
causes,  as  we  know,  are  at  work,  which  tend  to  modify,  if 
they  do  not  at  length  destroy,  all  the  arrangements  and 
dimensions  of  the  earth  and  the  whole  solar  system.  But 
though  in  the  course  of  ages  catastrophes  have  occurred 
and  may  yet  occur  in  the  heavens,  though  ancient  systems 
may  be  dissolved  and  new  systems  evolved  out  of  their 
ruins,  the  molecules  out  of  which  these  systems  are  built — 
the  foundation  stones  of  the  material  universe— remain 
unbroken  and  unworn." 

The  atomic  doctrine,  in  whole  or  in  part,  was  entertained 
by  Bacon,  Descartes,  Hobbes,  Locke,  Newton,  Boyle,  and 
their  successors,  until  the  chemical  law  of  multiple  pro- 
portions enabled  Dalton  to  confer  upon  it  an  entirely  new 
significance.  In  our  day  there  are  secessions  from  the 
theory,  but  it  still  stands  firm.  Loschmidt,  Stoney,  and 
Sir  William  Thomson  have  sought  to  determine  the  sizes 
of  the  atoms,  or  rather  to  fix  the  limits  between  which 
their  sizes  lie;  while  the  discourses  of  Williamson  and  Max- 
well delivered  in  Bradford  in  1873  illustrate  the  present 


464  FRAGMENTS  OF  SCIENCE. 

hold  of  the  doctrine  upon  the  foremost  scientific  minds. 
In  fact,  it  may  be  doubted  whether,  wanting  this  funda- 
mental conception,  a  theory  of  the  material  universe  is 
capable  of  scientific  statement. 

.  t.tie.     -XX. «*  -«£. 

SECTION  5.— Ninety  years  subsequent  to  Gassendi  the 
doctrine  of  bodily  instruments,  as  it  may  be  called,  assumed 
immense  importance  in  the  hands  of  Bishop  Butler,  who, 
in  his  famous  "  Analogy  of  Religion/*  developed,  from  his 
own  point  of  "View,  and  with  consummate  sagacity,  a 
similar  idea.  The  bishop  still  influences  many  superior 
minds;  and  it  will  repay  us  to  dwell  for  a  moment  on  his 
views.  He  draws  the  sharpest  distinction  between  our  real 
selves  and  our  bodily  instruments.  He  does  not,  as  far  as  I 
rein ember^use  the  word  soul,  possibly  because  the  term  was 
so  hackneyed  in  his  day,  as  it  had  been  for  many  genera- 
tions previously.  But  he  speaks  of  "living  powers," 
"  perceiving  or  percipient  powers/' "  moving  agents,"  "  our- 
selves," in  the  same  sense  as  we  should  employ  the  term 
soul.  He  dwells  upon  the  fact  that  limbs  may  be  removed, 
and  mortal  diseases  assail  the  body,  the  mind,  almost  up 
to  the  moment  of  death,  remaining  clear.  He  refers 

7  to  sleep  and  to  swoon,  where  the  "  living  powers"  are  sus- 
pended but  not  destroyed.  He  considers  it  quite  as  easy 
to  conceive  of  existence  out  of  our  bodies  as  in  them;  that 
we  may  animate  a  succession  of  bodies,  the  dissolution  of 
all  of  them  having  no  more  tendency  to  dissolve  our  real 
selves,  or  "deprive  us  of  living  faculties — the  faculties  of 
perception  and  action — than  the  dissolution  of  any  foreign 
matter  which  we  are  capable  of  receiving  impressions  from, 

~"N>r  making  use  of  for  the  common  occasions  of  life."  This 
is  the  key  of  the  bishop's  position:  "  our  organized  bodies 
are  no  more  a  part  of  ourselves  than  any  other  matter 
around  us."  In  proof  of  this  he  calls  attention  to  the 
use  of  glasses,  which  "prepare  objects"  for  the  "percip- 
ient power"  exactly  as  the  eye  does.  The  eye  itself 
is  no  more  percipient  than  the  glass;  is  quite  as  much 
the  instrument  of  the  true  self,  and  also  as  foreign 
Va  »to  the  true  self,  as  the  glass  is.  "And  if  we  see  witli 

1     our  eyes  only  in  the  same  manner  as  we  do  with  glasses, 
the  like  may  justly  be  concluded  from  analogy  of  all  our 
senses." 
,    Lucretius,  as  you  are  aware,  reached  a  precisely  opposite 

.     •< 

.       f'  :,.  — 


.c^VC 

,< 


THE  PEL  FAS?  ADDH  JS8&  465 

conclusion:  and  it  certainly  would  be  interesting,  if  not 
profitable,  to  us  all,  to  hear  what  he  would  or  could  urge 
in  opposition  to  the  reasoning  of  the  bishop.  As  a  brief 
discussion  of  the  point  will  enable  us  to  see  the  bearings 
of  an  important  question,  I  will  here  permit  a  disciple  of 
Lucretius  to  try  the  strength  of  the  bishop's  position,  and 
then  allow  the  bishop  to  retaliate,  with  the  view  of  rolling 
back,  if  he  can,  the  difficulty  upon  Lucretius. 
The  argument  might  proceed  in  this  fashion:  — 
"  Subjected  to  the  test  of  mental  presentation  (  Vorstel- 
lung),  your  views,  most  honored  prelate,  would  offer  to 
many  minds  a  great,  if  not  an  insuperable  difficulty.  You 
speak  of  'living  powers/  'percipient  or  perceiving 
powers/  and  'ourselves;'  but  can  you  form  a  mental 
picture  of  any  of  these,  apart  from  the  organism  through 
which  it  is  supposed  to  act?  Test  yourself  honestly,  and 
see  whether  you  possess  any  faculty  that  would  enable  you 
to  form  such  a  conception.  The  true  self  has  a  local  habi- 
tation in  each  of  us;  thus  localized,  must  it  not  possess  a 
form?  If  so,  what  form?  Have  you  ever  for  a  moment 
realized  it?  When  a  leg  is  amputated  the  body  is  divided 
into  two  parts;  is  the  true  self  in  both  of  them  or  in  one? 
Thomas  Aquinas  might  say  in  both;  but  not  you,  for  you 
appeal  to  the  consciousness  associated  with  one  of  the  two 
parts,  to  prove  that  the  other  is  foreign  matter.  Is  con- 
sciousness, then,  a  necessary  element  of  the  true  self?  If 
so,  what  do  you  say  to  the  case  of  the  whole  body  being 
deprived  of  consciousness?  If  not,  then  on  what  grounds 
do  you  deny  any  portion  of  the  true  self  to  the  severed 
limb?  It  seems  very  singular  that,  from  the  beginning  to 
the  end  of  your  admirable  book  (and  no  one  admires  its 
sober  strength  more  than  I  do),  you  never  once  mention 
the  brain  or  nervous  system.  You  begin  at  one  end  of  the 
body,  and  show  that  its  parts  may  be  removed  without 
prejudice  to  the  perceiving  power.  What  if  you  begin  at 
the  other  end,  and  remove,  instead  of  the  leg,  the  brain? 
The  body,  as  before,  is  divided  into  two  parts;  but  both 
are  now  in  the  same  predicament,  and  neither  can  be 
appealed  to  to  prove  that  the  other  is  foreign  matter.  Or, 
instead  of  going  so  far  as  to  remove  the  brain  itself,  let  a 
certain  portion  of  its  bony  covering  be  removed,  and  let  a 
rhythmic  series  of  pressures  and  relaxations  of  pressure  be 
applied  to  the  soft  substance.  At  every  pressure  '  the 


466  FRAGMENTS  Off  SCIENCE. 

faculties  of  perception  and  of  action '  vanish;  at  every 
relaxation  of  pressure  they  are  restored.  Where,  during 
the  intervals  of  pressure,  is  the  perceiving  power?  I  once 
had  the  discharge  of  a  large  Leyden  battery  passed  unex- 
pectedly through  me:  I  felt  nothing,  but  \vassirnply  blotted 
out  of  conscious  existence  for  a  sensible  interval.  Where 
was  my  true  self  during  that  interval?  Men  who  have 
recovered  from  lightning-stroke  have  been  much  longer  in 
the  same  state;  and  indeed  in  cases  of  ordinary  concussion 
of  the  brain,  days  may  elapse  during  which  no  experience 
is  registered  in  consciousness.  Where  is  the  man  himself 
during  the  period  of  insensibility?  You  may  say  that  I 
beg  the  question  when  I  assume  the  man  to  have  been 
unconscious,  that  he  was  really  conscious  all  the  time,  and 
has  simply  forgotten  what  had  occurred  to  him.  In  reply 
to  this,  I  can  only  say  that  no  one  need  shrink  from  the 
worst  tortures  that  superstition  ever  invented,  if  only  so 
felt  and  so  remembered.  I  do  not  think  your  theory  of 
instruments  goes  at  all  to  the  bottom  of  the  matter.  A 
telegraph  operator  has  his  instruments,  by  means  of  which 
he  converses  with  the  world;  our  bodies  possess  a  nervous 
system,  which  plays  a  similar  part  between  the  perceiving 
power  and  external  things.  Cut  the  wires  of  the  operator, 
break  his  battery,  demagnetize  his  needle;  by  this  means 
you  certainly  sever  his  connection  with  the  world;  but, 
inasmuch  as  these  are  real  instruments,  their  destruction 
does  not  touch  the  man  who  uses  them.  The  operator  sur- 
vives, and  he  knows  that  he  survives.  What  is  there,  I 
would  ask,  in  the  human  system  that  answers  to  this  con- 
scious survival  of  the  operator  when  the  battery  of  the  brain 
is  so  disturbed  as  to  produce  insensibility,  or  when  it  is 
destroyed  altogether? 

"Another  consideration,  which  you  may  regard  as 
slight,  presses  upon  me  with  some  force.  The  brain  may 
change  from  health  to  disease,  and  through  such  a  change 
the  most  exarnplary  man  may  be  converted  intoa  debauchee 
or  a  murderer.  My  very  noble  and  approved  good  master 
had,  as  you  know,  threatenings  of  lewd  ness  introduced  into 
his  brain  by  his  jealous  wife's  philter;  and  sooner  than 
permit  himself  to  run  even  the  "risk  of  yielding  to  these 
base  promptings  he  slew  himself.  How  could  the  hand  of 
Lucretius  have  been  thus  turned  against  himself  if  the  real 
Lucretius  remained  as  before?  Can  the  brain  or  can  it 


THE  BELFAST  ADDRESS.  407 

not  act  in  this  distempered  way  without  the  intervention 
of  the  immortal  reason?  If  it  can,  then  it  is  a  prime  mover 
which  requires  only  healthy  regulation  to  render  it  reason- 
ably self-actiTig,  and  there  is  no  apparent  need  of  your 
immortal  reason  at  all.  If  it  cannot,  then  the  immortal 
reason,  by  its  mischievous  activity  in  operating  upon  a 
broken  instrument,  must  have  the  credit  of  committing 
every  imaginable  extravagance  and  crime.  I  think,  if  you 
will  allow  me  to  say  so,  that  the  gravest  consequences  are 
likely  to  flow  from  your  estimate  of  the  body.  To  regard 
the  brain  as  you  would  a  staff  or  an  eyeglass — to  shut  your 
eyes  to  all  its  mystery,  to  the  perfect  correlation  of  its 
condition  and  our  consciousness,  to  the  fact  that  a  slight 
excess  or  defect  of  blood  in  it  produces  the  very  swoon  to 
which  you  refer,  and  that  in  relation  to  it  our  meat,  and 
drink,  and  air,  and  exercise,  have  a  perfectly  transcend- 
ental value  and  significance — to  forgot  all  this  does,  I 
think,  open  a  way  to  innumerable  errors  in  our  habits  of 
life,  and  may  possibly,  in  some  cases,  initiate  and  foster 
that  very  disease,  and  consequent  mental  ruin,  which  a 
wiser  appreciation  of  this  mysterious  organ  would  have 
avoided." 

I  can  imagine  the  bishop  thoughtful  after  hearing  this 
argument.  He  was  not  the  man  to  allow  anger  to  mingle 
with  the  consideration  of  a  point  of  this  kind.  After  due 
reflection,  and  having  strengthened  himself  by  that  honest 
contemplation  of  the  facts  which  was  habitual  with  him, 
and  which  includes  the  desire  to  give  even  adverse  reason- 
ings their  due  weight,  I  can  suppose  the  bishop  to  proceed 
thus:  "  You  will  remember  that  in  the  "  Analogy  of  Reli- 
gion," of  which  you  have  so  kindly  spoken,  1  did  not 
profess  to  prove  anything  absolutely,  and  that  I  over  and 
over  again  acknowledged  and  insisted  on  the  smallness  of 
our  knowledge,  or  rather  the  depth  of  our  ignorance,  as 
regards  the  whole  system  of  the  universe.  My  object  was 
to  show  my  deistical  friends,  who  set  forth  so  eloquently 
the  beauty  and^eneficence  of  Nature  and  the  Ruler  thereof, 
while  they  had  nothing  but  scorn  for  the  so-called  absurd- 
ities of  the  Christian  scheme,  that  they  were  in  no  better 
condition  than  we  were,  and  that,  for  every  difficulty  found 
upon  our  side,  quite  as  great  a  difficulty  was  to  be  found 
upon  theirs.  I  will  now,  with  your  permission,  adopt  a 
similar  line  of  argument.  You  are  a  Lucretian,  and  from 


468  FRAGMENTS  OP  SCIENCE. 

the  combination  and  separation  of  insensate  atoms  deduce 
all  terrestrial  things,  including  organic  forms  and  their 
phenomena.  Let  me  tell  you  in  the  first  instance  how 
far  I  am  prepared  to  go  with  you.  I  admit  that  you  can 
build  crystalline  forms  out  of  this  play  of  molecular  force; 
that  the  diamond,  amethyst,  and  snow-star  are  truly  won- 
derful structures  which  are  thus  produced.  I  will  go 
further  and  acknowledge  that  even  a  tree  or  flower  might 
in  this  way  be  organized.  Nay,  if  you  can  show  me 
an  animal  without  sensation,  I  will  concede  to  you  that  it 
also  might  be  put  together  by  the  suitable  play  of  molec- 
ular force. 

"Thus  far  our  way  is  clear,  but  now  comes  my  diffi- 
culty. Your  atoms  are  individually  without  sensation, 
much  more  are  they  without  intelligence.  May  I  ask  you, 
then,  to  try  your  hand  upon  this  problem.  Take  your 
dead  hydrogen  atoms,  your  dead  oxygen  atoms,  your  dead 
carbon  atoms,  your  dead  nitrogen  atoms,  your  dead  phos- 
phorus atoms,  and  all  the  other  atoms,  dead  as  grains  of 
shot,  of  which  the  brain  is  formed.  Imagine  them  sepa- 
rate and  sensationless;  observe  them  running  together  and 
forming  all  imaginable  combinations.  This,  as  a  purely 
mechanical  process,  is  seeaUe  by  the  mind.  But  can  you 
see,  or  dream,  or  in  any  way  imagine,  how  out  of  that 
mechanical  act,  and  from  these  individually  dead  atoms, 
sensation,  thought,  and  emotion  are  to  rise?  Are  you 
likely  to  extract  Homer  out  of  the  rattling  of  dice,  or  the 
Differential  Calculus  out  of  the  clash  of  billiard-balls?  I 
am  not  all  bereft  of  this  Vorstellungs-Kraft  of  which  you 
speak,  nor  am  I,  like  so  many  of  my  brethren,  a  mere 
vacuum  as  regards  scientific  knowledge.  I  can  follow  a  par- 
ticle of  rnusk  until  it  reaches  the  olfactory  nerve;  I  can 
follow  the  waves  of  sound  until  their  tremors  reach  the 
water  of  the  labyrinth,  and  set  the  qtolrths  and  Corti's 
fibers  in  motion;  I  can  also  visualize  the  waves  of  ether  as 
they  cross  the  eye  and  hit  the  retina.  Nay  more,  I  am 
able  to  pursue  to  the  central  organ  the  motion  thus  imparted 
at  the  periphery,  and  to  see  in  idea  the  very  molecules  of 
the  braiTTEhrown  into  tremors.  My  insight  is  not  baffled 
by  these  physical  processes.  "What  baffles  and  bewilders 
me  is  the  notion  that  from  those  physical  tremors  things 
so  utterly  incongruous  with  them  as  sensation,  thought, 
and  emotion  can  be  derived.  You  may  say,  or  think,  that 


THE  BELFAST  ADDRESS.  469 

this  issue  of  consciousness  from  the  clash  of  atoms  is  not 
more  incongruous  than  the  flash  of  light  from  the  union  of 
oxygen  and  hydrogen.  But  I  beg  to  say  that  it  is.  For 
such  incongruity  as  the  flash  possesses  is  that  which  I  now 
force  upon  your  attention.  The  "flash"  is  an  affair  of 
consciousness,  the  objective  counterpart  of  which  is  a 
vibration.  It  is  a  flash  only  by  your  interpretation.  You 
are  the  cause  of  the  apparent  incongruity;  and  you  are  the 
thing  that  puzzles  me.  I  need  not  remind  you  that  the 
great  Leibiiitz  felt  the  difficulty  which  I  feel;  and  that  to 
get  rid~bf  this  monstrous  deduction  of  life  from  death  he 
displaced  your  atoms  by  his  monads,  which  were  more  or 
less  perfect  mirrors  of  the  universe,  and  out  of  the  sum- 
mation and  integration  of  which  he  supposed  all  the 
phenomena  of  life — sentient,  intellectual,  and  emotional — 
to  arise. 

"  Your  difficulty,  then,  as  I  see  you  are  ready  to  admit, 
is  quite  as  great  as  mine.  You  cannot  satisfy  the  human 
understanding  in  its  demand  for  logical  continuity  between 
molecular  processes  and  the  phenomena  of  consciousness. 
This  is  a  rock  on  which  Materialism  must  inevitably  split 
whenever  it  pretends  to  be  a  complete  philosophy  of  life. 
What  is  the  moral,  my  Lucre tiau?  You  and  I  are  not 
likely  to  indulge  in  ill-temper  in  the  discussion  of  these 
great  topics,  where  we  see  so  much  room  for  honest  differ- 
ences of  opinion.  But  there  are  people  of  less  wit  or  more 
bigotry  (I  say  it  with  humility),  on  both  sides,  who  are 
ever  ready  to  mingle  auger  and  vituperation  with  such  dis- 
cussions. There  are,  for  example,  writers  of  note  and  in- 
fluence at  the  present  day,  who  are  not  ashamed  publicly 
to  assume  the  "  deep  personal  sin  "  of  a  great  logician  to 
be  the  cause  of  his  unbelief  in  a  theologic  dogma.*  And 
there  are  others  who  hold  that  we,  who  cherish  our  noble 
Bible,  wrought  as  it  has  been  into  the  constitution  of  our 
forefathers,  and  by  inheritance  into  us,  must  necessarily  be 
hypocritical  and  insincere.  Let  us  disavow  and  discoun- 
tenance such  people,  cherishing  the  unswerving  faith  that 

*  This  is  the  aspect  under  which  the  late  editor  of  the  "Dublin 
Review  "  presented  to  his  readers  the  memory  of  John  Stuart  Mill. 
I  can  only  say,  that  1  would  as  soon  take  my  chance  in  the  other 
world,  in  the  company  of  the  "  unbeliever,"  as  in  that  of  his  Jesuit 
detractor.  In  Dr.  Ward  we  have  an  example  of  a  wholesome  aud 
vigorous  uature,  soured  aud  perverted  by  a  poisonous  creed. 


4?0  FRAGMENTS  OF  SCIENCE. 

what  is  good  and  true  in  both  our  arguments  will  be  pre- 
served for  the  benefit  of  humanity,  while  all  that  is  bad  or 
false  will  disappear." 

I  hold  the  bishop's  reasoning  to  be  unanswerable,  and 
his  liberality  to  be  worthy  of  imitation. 

It  is  worth  remarking  that  in  one  respect  the  bishop  was 
a  product  of  his  age.  Long  previous  to  his  day  the  nature 
of  the  soul  had  been  so  favorite  and  general  a  topic  of  dis- 
cussion, that,  when  the  students  of  the  Italian  universities 
wished  to  know  the  leanings  of  a  new  professor,  they  at 
once  requested  him  to  lecture  upon  the  soul.  About  the 
time  of  Bishop  Butler  the  question  was  not  only  agitated 
but  extended.  It  was  seen  by  the  clear-witted  men  who 
entered  this  arena,  that  many  of  their  best  arguments 
applied  equally  to  brutes  and  men.  The  bishop's  argu- 
ments were  of  this  character.  He  saw  it,  admitted  it,  took 
the  consequence,  and  boldly  embraced  the  whole  animal 
world  in  his  scheme  of  immortality. 

SECTION"  6. — Bishop  Butler  accepted  with  unwavering 
trust  the  chronology  of  the  Old  Testament,  describing  it 
as  "  confirmed  by  the  natural  and  civil  history  of  the 
world,  collected  from  common  historians,  from  the  state  of 
the  earth,  and  from  the  late  inventions  of  arts  and 
sciences."  These  words  mark  progress;  and  they  must 
seem  somewhat  hoary  to  the  bishop's  successors  of  to-day. 
It  is  hardly  necessary  to  inform  you  that  since  his  time 
the  domain  of  the  naturalist  has  been  immensely  extended 
—the  whole  science  of  geology,  with  its  astounding 
revelations  regarding  the  life  of  the  ancient  earth,  having 
been  created.  The.  rigidity  of  old  conceptions  has  been 
relaxed,  the  public  mind  being  rendered  gradually  tolerant 
of  the  idea  fchat  not  for  six  thousand,  nor  for  sixty  thousand, 
nor  for  six  thousand  thousand,  but  for  aeons  embracing 
untold  millions  of  years,  this  earth  has  been"  "the  theater  of 
life  and  death.  The  riddle  of  the  rocks  has  been  read  by 
the  geologist  and  palaeontologist,  sub-cambrian  depths  to 
the  deposits  thickening  over  the  sea-bottoms  of  to-day. 
And  upon  the  leaves  of  that  stone  book  are,  as  you  know, 
stamped  the  characters,  plainer  and  surer  than  those 
formed  by  the  ink  of  history,  which  carry  the  mind  back 
into  abysses  of  past  time,  compared  with  which  the  periods 
which  satisfied  Bishop  Butler  cease  to  have  a  visual  angle. 


THE  BELFAST  ADDRESS.  471 

The  Igde  of  discovery  once  struck,  those  petrified  forms 
in  which  life  was  at  one  time  active,  increased  to  multitudes 
and  demanded  classification.  They  were  grouped  in 
genera,  species,  and  varieties,  according  to  the  degree  of 
similarity  subsisting  between  them.  Thus  confusion  was 
avoided,  each  object  being  found  in  the  pigeon-hole 
appropriated  to  it  and  to  its  fellows  of  similar  morphological 
or  physiological  character.  The  general  fact  soon  became 
evident  that  none  but  the  simplest  forms  of  life  lie  lowest 
down;  that,  as  we  climb  higher  among  the  superimposed 
strata,  more  perfect  forms  appear.  The  change,  however, 
from  form  to  form  was  not  continuous,  but  by  steps — some 
small,  some  great.  "A  section,"  says  Mr.  Huxley,  "a 
hundred  feet  thick  will  exhibit  at  different  heights  a 
dozen  species  of  Amnionite,  none  of  which  passes  beyond 
the  particular  zone  of  limestone,  or  clay,  into  the  zone 
below  it,  or  into  that  above  it."  In  the  presence  of  such 
facts  it  was  not  possible  to  avoid  the  question:  Have  these 
forms,  showing,  though  in  broken  stages,  and  with  many 
irregularities,  this  unmistakable  general  advance,  being 
subjected  to  no  continuous  law  of  growth  or  variation? 
Had  our  education  been  purely  scientific,  or  had  it  been 
sufficiently  detached  from  influences  which,  however 
ennobling  in  another  domain,  have  always  proved  hindrances 
and  delusions  when  introduced  as  factors  into  the  domain 
of  physics,  the  scientific  mind  never  could  have  swerved 
from  the  search  for  a  law  of  growth,  or  allowed  itself  to 
accept  the  anthropomorphism  which  regarded  each  suc= 
cessive  stratum  as  a  kind  of  mechanic's  bench  for  the 
manufacture  of  new  species  out  of  all  relation  to  the  old. 

Biased,  however,  by  their  previous  education,  the 
great  majority  of  naturalists  invoked  a  special  creative 
act  to  account  for  the  appearance  of  each  new  group  of 
organisms.  Doubtless  numbers  of  them  were  clear-headed 
enough  to  see  that  this  was  no  explanation  at  all-1— that,  in 
point  of  fact,  it  was  an  attempt,  by  the  introduction  of  a 
greater  difficulty,  to  account  for  a  less.  But,  having 
nothing  to  offer  in  the  way  of  explanation,  they  for  the 
most  part  held  their  peace.  Still  the  thoughts  of  reflect- 
ing men  naturally  and  necessarily  simmered  round  the 
question.  De  Maillet,  a  contemporary  of  Newton,  has 
been  brought  tTTto  notice  by  Professor  Huxley  as  one  who 
"  had  a  notion  of  the  modifiability  of  living  forms,"  The 


472  FRAGMENTS  OF  SCIENCE. 

late  Sir  Benjamin  Brodie,  a  man  of  highly  philosophic 
mind,  often  drew  my  attention  to  the  fact  that,  as  early  as 
1794,  Charles  Darwin's  grandfather  was  the  pioneer  of 
Charles  Darwin.*  In  1801,  and  in  subsequent  years,  the 
celebrated  Lamarck,  who,  through  the  vigorous  exposition 
of  his  views  by  the  author  of  the  "Vestiges  of  Creation," 
rendered  the  public  mind  perfectly  familiar  with  the  idea 
of  evolution,  endeavored  to  show  the  development  of 
species  out  of  changes  of  habit  and  external  condition.  In 
1813  Dr.  Wells,  the  founder  of  our  present  theory  of  Dew, 
read  before  the  Royal  Society  a  paper  in  which,  to  use  the 
words  of  Mr.  Darwin,  "he  distinctly  recognizes  the  prin- 
ciple of  natural  selection;  and  this  is  the  first  recognition 
that  has  been  indicated."  The  thoroughness  and  skill 
with  which  Wells  pursued  his  work,  and  the  obvious  inde- 
pendence of  his  character,  rendered  him  long  ago  a  favorite 
with  me;  and  it  gave  me  the  liveliest  pleasure  to  alight 
upon  this  additional  testimony  to  his  penetration.  Pro- 
fessor Grant,  Mr.  Patrick  Matthew,  Von  Buch,  the  author 
of  the  "  Vestiges,"  D'Halloy,  and  others,  by  the  enuncia- 
tion of  opinions  more  or  less  clear  and  correct,  showed 
that  the  question  had  been  fermenting  long  prior  to  the 
year  1858,  whn  Mr.  Darwin  and  Mr.  Wallace  simul- 
taneously, but  independently,  placed  their  closely  con- 
current views  before  the  Linnean  Society. f 

These  papers  were  followed  in  1859  by  the  publication 
of  the  first  edition  of  the  "  Origin  of  Species."  All  great 
things  come  slowly  to  the  birth.  Copernicus,  as  I  informed 
vou,  pondered  his  great  work  for  thirty-three  years. 
Newton  for  nearly  twenty  years  kept  the  idea  of  Gravita- 
tion before  his  mind;  for  twenty  years  also  he  dwelt  upon 
iiis  discovery  of  Fluxions,  and  doubtless  would  have  con- 
tinued to  make  it  the  object  of  his  private  thought,  hud 
he  not  found  Leibnitz  upon  his  track.  Darwin  for  two- 
and-twenty  years  pondered  the  problem  of  the  origin  of 
species,  and  doubtless  he  would  have  continued  to  do  so  had 

*  "  Zoonomia,"  vol.  i.  pp.  500-510. 

fin  1855  Mr.  Herbert  Spencer  ("  Principles  of  Psychology,"  2d 
edit.  vol.  i.  p.  465 )  expressed  "the  belief  that  life  under  all  its  forms 
has  arisen  by  an  unbroken  evolution,  and  through  the  instrumen- 
tality of  what  are  called  natural  causes."  This  was  my  belief  also 
'at  that  time. 


THE  BEE  FAST  ADDR  KSS.  473 

he  not  found  Wallace  upon  his  track.*  A  concentrated, 
but  full  and  powerful,  epitome  of  his  labors  was  the  con- 
sequence. The  book  was  by  no  means  an  easy  one;  and 
probably  not  one  in  every  score  of  those  who  then  attacked 
it,  hud  read  its  pages  through,  or  were  competent  to  grasp 
their  significance  if  they  had.  I  do  not  say  this  merely  to 
discredit  them:  for  there  were  in  those  days  some  really 
eminent  scientific  men,  entirely  raised  above  the  heat  of 
popular  prejudice,  and  willing  to  accept  any  conclusion 
that  science  had  to  offer,  provided  it  was  duly  backed  by 
fact  and  argument,  who  entirely  mistook  Mr.  Darwin's 
views.  In  fact,  the  work  needed  an  expounder,  and  it 
found  one  in  Mr.  Huxley.  I  know  nothing  more  admirable 
in  the  way  of  scientific  exposition  than  those  early  articles 
of  his  on  the  origin  of  species.  He  swept  the  curve  of 
discussion  through  the  really  significant  points  of  the  sub- 
ject, enriched  his  exposition  with  profound  original  remarks 
and  reflections,  often  summing  up  in  a  single  pithy  sen- 
tence an  argument  which  a  less  compact  mind  would  have 
spread  over  pages.  But  there  is  one  impression  made  by 
the  book  itself  which  no  exposition  of  it,  however  luminous, 
can  convey;  and  that  is  the  impression  of  the  vast  amount 
of  labor,  both  of  observation  and  of  thought,  implied  in 
its  production.  Let  us  glance  at  its  principles. 

It  is  conceded  on  all  hands  that  what  are  called  "  varie- 
ties "are  continually  produced.  The  rule  is  probably 
without  exception.  No  chick,  or  child,  is  in  all  respects 
and  particulars  the  counterpart  of  its  brother  and  sister: 
and  in  such  differences  we  have  "  variety"  incipient.  No 
naturalist  could  tell  how  far  this  variation  could  be  carried; 
but  the  great  mass  of  them  held  that  never,  by  any  amount 
of  internal  or  external  change,  nor  by  the  mixture  of  both, 
could  the  offspring  of  the  same  progenitor  so  far  deviate 
from  each  other  as  to  constitute  different  species.  The 
function  of  the  experimental  philosopher  is  to  combine  the 
conditions  of  Nature  and  to  produce  her  results;  and  this 
was  the  method  of  Darwin,  f  He  made  himself  acquainted 

*  The  behavior  of  Mr.  Wallace  iu  relation  to  this  subject  has  been 
dignified  in  the  highest  degree. 

f  The  first  step  only  toward  experimental  demonstration  has  been 
taken.  Experiments  now  begun  might,  a  couple  of  centuries  hence, 
furnish  data  of  incalculable  value,  which  ought  to  be  supplied 
science  of  the  future. 


474  FRAGMENTS  OF  SCIENCE. 

with  what  could,  without  any  manner  of  doubt,  be  done 
in  the  way  of  producing  variation.  He  associated  himself 
with  pigeon-fanciers — bought,  begged,  kept,  and  observed 
every  breed  that  he  could  obtain.  Though  derived  from  a 
common  stock,  the  diversities  of  these  pigeons  were  such 
that  "a  score  of  them  might  be  chosen  which,  if  shown  to 
an  ornithologist,  and  he  were  told  that  they  were  wild 
birds,  WQuld  certainly  be  ranked  by  him  as  well-defined 
species."  The  simple  principle  which  guides  the  pigeon- 
fancier,  as  it  does  the  cattle-breeder,  is  the  selection  of 
some  variety  that  strikes  his  fancy,  and  the  propagation  of 
this  variety  by  inheritance.  With  his  eye  still  directed  to 
the  particular  appearance  which  he  wishes  to  exaggerate, 
he  selects  it  as  it  reappears  in  successive  broods,  and  thus 
adds  increment  to  increment  until  an  astonishing  amount 
of  divergence  from  the  parent  type  is  effected.  The 
breeder  in  this  case  does  not  produce  the  elements  of  the 
variation.  He  simply  observes  them,  and  by  selection  adds 
them  together  until  the  required  result  has  been  obtained. 
"No  man,"  says  Mr.  Darwin,  "  would  ever  try  to  make  a 
fantail  till  he  saw  a  pigeon  with  a  tail  developed  in  some 
slight  degree  in  an  unusual  manner,  or  a  pouter  until  he 
saw  a  pigeon  with  a  crop  of  unusual  size."  jThns  natilie 
gives  the  hint,  man  acts  upon  it,  and  by  the  law  of  inherit- 
ance exaggerates  the  deviation. 

1  Living  thus  satisfied  himself  by  indubitable  facts  that 
the  organization  of  an  animal  or  of  a  plant  (for  precisely 
the  same  treatment  applies  to  plants)  is  to  some  extent 
plastic,  he  passes  from  variation  under  domestication  to 
variation  under  nature.  Hitherto  we  have  dealt  with  the 
adding  together  of  small  changes  by  the  conscious  selection 
of  man.  Can  Nature  thus  select?  Mr.  Darwin's  answer 
is  "  Assuredly  she  can."  The  number  of  living  things 
produced  is  far  in  excess  of  the  number  that  can  be  sup- 
ported; hence  at  some  period  or  other  of  their  lives  there 
must  be  a  struggle  for  existence.  And  what  is  the  infal- 
lible result?  If  one  organism  were  a  perfect  copy  of  the 
other  in  regard  to  strength,  skill,  and  agility,  external 
conditions  would  decide.  But  this  is  not  the  case.  Here 
we  have  the  fact  of  variety  offering  itself  to  nature,  as  in 
the  former  instance  it  offered  itself  to  man;  and  those 
varieties  which  are  least  competent  to  cope  with  sur- 
rounding conditions  will  infallibly  give  way  to  those  that 


THE  BELFAST  ADDRESS.  475 

are  most  competent.  To  use  a  familar  proverb,  the  weak- 
est goes  to  the  wall.  But  the  triumphant  fraction  again 
breeds  to  over-production,  transmitting  the  qualities  which 
secured  its  maintenance,  but  transmitting  them  indifferent 
degrees.  The  struggle  for  food  again  supervenes,  and  those 
to  whom  the  favorable  quality  has  been  transmitted  in 
excess,  will  triumph  as  before. 

It  is  easy  to  see  that  we  have  here  the  addition  of  incre- 
ments favorable  to  the  individual,  still  more  rigorously 
carried  out  than  in  the  case  of  domestication;  for  not  only 
are  unfavorable  specimens  not  selected  by  nature,  but  they 
are  destroyed.  This  is  what  Mr.  Darwin  calls  "Natural 
Selection,"  which  acts  by  the  preservation  and  accumula- 
tion of  small  inherited  modifications,  each  profitable  to  the 
preserved  being.  With  this  idea  he  interpenetrates  and 
leavens  the  vast  store  of  facts  that  he  and  others  have  col- 
lected. We  cannot,  without  shutting  our  eyes  through 
fear  or  prejudice,  fail  to  see  that  Darwin  is  here  dealing, 
not  with  imaginary,  but  with  true  causes;  nor  can  we  fail 
to  discern  what  vast  modifications  may  be  produced  by 
natural  selection  in  periods  sufficiently  long.  Each  indi- 
vidual increment  may  resemble  what  mathematicians  call  a 
"  differential  "  (a  quantity  indefinitely  small);  but  definite 
and  great  changes  may  obviously  be  produced  by  the  inte- 
gration of  these  infinitesimal  quantities,  through  practically 
infinite  time. 

If  Darwin,  like  Bruno,  rejects  the  notion  of  creative 
power,  acting  after  human  fashion,  it  certainly  is  not  be- 
cause he  is  unacquainted  with  the  numberless  exquisite 
adaptations  on  which  this  notion  of  a  supernatural  Artificer 
has  been  founded.  His  book  is  a  repository  of  the  most 
startling  facts  of  this  description.  Take  the  marvelous 
observation  which  he  cites  from  Dr.  Kriiger,  where  a  bucket, 
with  an  aperture  serving  as  a  spout,  is  formed  in  an  orchid. 
Bees  visit  the  flower:  in  eager  search  of  material  for  their 
combs,  they  push  each  other  into  the  bucket,  the  drenched 
ones  escaping  from  their  involuntary  bath  by  the  spout. 
Here  they  rub  their  backs  against  the  viscid  stigma  of  the 
flower  and  obtain  glue;  then  against  the  pollen-masses, 
which  are  thus  stuck  to  the  back  of  the  bee  and  carried 
away.  "  When  the  bee,  so  provided,  flies  to  another  flower 
or  to  the  same  flower  a  second  time,  and  is  pushed  by  its 
comrades  into  the  bucket,  and  then  crawls  out  by  the 


476  FRAGMENTS  OF  SCIENCE. 

passage,  the  pollen-mass  upon  its  back  necessarily  comes 
first  into  contact  with  the  viscid  stigma/'  which  takes  up 
the  pollen;  and  this  is  how  that  orchid  is  fertilized.  Or 
take  this  other  case  of  the  Catasetum.  "Bees  visit  these 
flowers  in  order  to  gnaw  the  labellurn;  in  doing  this  they 
inevitably  touch  a  long,  tapering,  sensitive  projection. 
This,  when  touched,  transmits  a  sensation  or  vibration  to 
a  certain  membrane,  which  is  instantly  ruptured,  setting 
free  a  spring,  by  which  the  pollen-mass  is  shot  forth  like  an 
arrow  in  the  right  direction,  and  adheres  by  its  viscid  ex- 
tremity to  the  back  of  the  bee."  In  this  way  the  fertilizing 
pollen  is  spread  abroad.  ^J^^-  TJ  V*" 

It  is  the  mind  thus  stored  with  the  choicest  materials  of 
the  teleplogist  that  rejects  teleology,  seeking  to  refer  these 
wonders  to  natural  causes.  They  illustrate,  according  to 
him,  the  method  of  nature,  not  the  "  technic"  of  a  man- 
like Artificer.  The  beauty  of  flowers  is  due  to  natural 
selection.  Those  that  distinguish  themselves  by  vividly 
contrasting  colors  from  the  surrounding  green  leaves  are 
most  readily  seen,  most  frequently  visited  by  insects,  most 
often  fertilized,  and  hence  most  favored  by  natural  selec- 
tion. Colored  berries  also  readily  attract  the  attention  of 
birds  and  beasts,  which  feed  upon  them,  spread  their 
manured  seeds  abroad,  thus  giving  trees  and  shrubs  possess- 
ing such  berries  a  greater  chance  in  the  struggle  for 
existence. 

With  profound  analytic  and  synthetic  skill,  Mr.  Darwin 
investigates  the  cell-making  instinct  of  the  hive-bee.  His 
method  of  dealing  with  it  is  representative.  He  falls  back 
from  the  more  perfectly  to  the  less  perfectly  developed 
instinct — from  the  hive-bee  to  tne  humble-bee,  which  uses 
its  own  cocoon  as  a  comb,  and  to  classes  of  bees  of  inter- 
mediate skill,  endeavoring  to  show  how  the  passage  might 
be  gradually  made  from  the  lowest  to  the  highest.  The 
saving  of  wax  is  the  most  important  point  in  the  economy 
of  bees.  Twelve  to  fifteen  pounds  of  dry  sugar  are  said  to 
be  needed  for  the  secretion  of  a  single  pound  of  wax.  The 
quantities  of  nectar  necessary  for  the  wax  must  therefore 
be  vast;  and  every  improvement  of  constructive  instinct 
which  results  in  the  saving  of  wax  is  a  direct  profit  to  the 
insect's  life.  The  time  that  would  otherwise  be  devoted 
to  the  making  of  wax,  is  devoted  to  the  gathering  and 
storing  of  honey  for  winter  food.  Mr.  Darwin  passes  from, 


THE  BELFAST^  ADDRESS.  477 

the  humble-bee  with  its  rude  cells,  through  the  Melipona 
with  its  more  artistic  cells,  to  the  hive-bee  with  its  astonish- 
ing architecture.  The  bees  place  themselves  at  equal 
distances  apart  upon  the  wax,  sweep  and  excavate  equal 
spheres  round  the  selected  points.  The  spheres  intersect, 
and  the  planes  of  intersection  are  built  up  with  thin 
laminae.  Hexagonal  cells  are  thus  formed.  This  mode 
of  treating  such  questions  is,  as  I  have  said,  representa- 
tive. The  expositor  habitually  retires  from  the  more 
perfect  and  complex,  to  the  less  perfect  and  simple,  and 
carries  you  with  him  through  stages  of  perfecting — adds 
increment  to  increment  of  infinitesimal  change,  and  in  this 
way  gradually  breaks  down  your  reluctance  to  admit  that 
the  exquisite  climax  of  the  whole  could  be  a  result  of 
natural  selection, 

Mr.  Darwin  shirks  no  difficulty;  and,  saturated  as  the  sub- 
ject was  with  his  own  thought,  he  must  have  known, 
better  than  his  critics,  the  weakness  as  well  as  the  strength 
of  his  theory.  This  of  course  would  be  of  little  avail  were 
his  object  a  temporary  dialectic  victory,  instead  of  the 
establishment  of  a  truth  which  he  means  to  be  everlasting. 
But  he  tukes  no  pains  to  disguise  the  weakness  he  has  dis- 
cerned; nay,  he  takes  every  pains  to  bring  it  into  the 
strongest  light.  His  vast  resources  enable  him  to  cope  with 
objections  started  by  himself  and  others,  so  as  to  leave  the 
final  impression  upon  the  reader's  mind  that,  if  they  be  not 
completely  answered,  they  certainly  are  not  fatal.  Their 
negative  force  being  thus  destroyed,  you  are  free  to  be 
influenced  by  the  vast  positive  mass  of  evidence  he  is  able 
to  bring  before  you.  This  largeness  of  knowledge,  and 
readiness  of  resource,  render  Mr.  Darwin  the  most  terrible 
of  antagonists.  Accomplished  naturalists  have  leveled 
heavy  and  sustained  criticisms  against  him — not  always 
with  the  view  of  fairlv  weighing  his  theorv,  but  with  the 
express  intention  of  exposing  its  weak  points  only.  This 
does  not  irritate  him.  He  treats  every  objection  with  a 
soberness  and  thoroughness  which  even  Bishop  Butler 
might  be  proud  to  imitate,  surrounding  each  fact  with  its 
appropriate  detail,  placing  it  in  its  proper  relations,  and 
usually  giving  it  a  significance  which,  as  long  as  it  was 
kept  isolated,  failed  to  appear.  This  is  done  without  a 
trace  of  ill-temper.  He  moves  over  the  subject  with  the 
passionless  strength  of  a  glacier;  and  the  grinding  of  the 


478  PR 'A  GMENTS  0  F  SCIENCE. 

rocks  is  not  always  without  a  counterpart  in  the  logical 
pulverization  of  the  objector.  But  though  in  handling 
this  mighty  theme  all  passion  has  been  stilled,  there  is  an 
emotion  of  the  intellect,  incident  to  the  discernment  of 
new  truth,  which  often  colors  and  warms  the  pages  of  Mr. 
Darwin.  His  success  has  been  great;  and  this  implies  not 
only  the  solidity  of  his  work,  but  the  preparedness  of  the 
public  mind  for  such  a  revelation.  On  this  head,  a  remark 
of  Agassiz  impressed  me  more  than  anything  else.  Sprung 
from  a  race  of  theologians,  this  celebrated  man  combated 
to  the  last  the  theory  of  natural  selection.  One  of  the 
many  times  I  had  the  pleasure  of  meeting  him  in  the 
United  States  was  at  Mr.  Winthrop's  beautiful  residence  at 
Brookliue,  near  Boston.  Eising  from  luncheon,  we  all 
halted  as  if  by  common  consent,  in  front  of  a  window, 
and  continued  there  a  discussion  which  had  been  started  at 
table.  The  maple  was  in  its  autumn  glory,  and  the 
exquisite  beauty  of  the  scene  outside  seemed,  in  my  case, 
to  interpenetrate  without  disturbance  the  intellectual 
action.  Earnestly,  almost  sadly,  Agassiz  turned,  and  said 
to  the  gentlemen  standing  round, "I  confess  that  I  was  not 
prepared  to  see  this  theory  received  as  it  has  been  by  the 
best  intellects  of  our  time.  Its  success  is  greater  than  I 
could  have  thought  possible." 

SECTION  7. — In  our  day  grand  generalizations  have  been 
reached.  "  The  theory  of  the  origin  of  species  is  but  one  of 
them.  Another,  of  still  wider  grasp  and  more  radical 
significance,  is  the  doctrine  of  the  Conservation  of  Energy, 
the  ultimate  philosophical  issues  of  which  are  as  yet  but 
dimly  seen — that  doctrine  which  "binds  nature  fast  in 
fate,"  to  an  extent  not  hitherto  recognized,  exacting  from 
every  antecedent  its  equivalent  consequent,  from  every  con- 
sequent its  equivalent  antecedent,  and  bringing  vital  as 
well  as  physical  phenomena  under  the  dominion  of  that 
law  of  causal  connection  which,  so  far  as  the  human  under- 
standing has  yet  pierced,  asserts  itself  everywhere  in 
nature.  Long  in  advance  of  all  definite  experiment  upon 
the  subject,  the  constancy  and  indestructibility  of  matter 
had  been  affirmed;  and  all  subsequent  experience  justified 
the  affirmation.  Majer  extended  the  attribute  of  inde- 
structibility to  energy,  applying  it  in  the  first  instance  to 


THE  BELFAST  ADDRK8S.  479 

inorganic,*  and  afterward  with  profound  insight  to  organic 
nature.  The  vegetable  world,  though  drawing  all  its 
nutriment  from  invisible  sources,  was  proved  incompetent 
to  generate  anew  either  matter  or  force.  Its  matter  is  for 
the  most  part  trans tnu ted  gas;  its  force  transformed  solar 
force.  The  animal  world  was  proved  to  be  equally  un- 
creative,  all  its  motive  energies  being  referred  to  the  com- 
bustion of  its  food.  The  activity  of  each  animal,  as  a 
whole,  was  proved  to  be  the  transferred  activity  of  its  mole- 
cules. The  muscles  were  shown  to  be  stores  of  mechanical 
energy,  potential  until  unlocked  by  the  nerves,  and  then 
resulting  in  muscular  contractions.  The  speed  at  which 
messages  fly  to  and  fro  along  the  nerves  was  determined  by 
Helmholtz,  and  found  to  be,  not,  as  had  been  previously 
supposed,  equal  to  that  of  light  or  electricity,  but  less  than 
the  speed  of  sound — less  even  than  that  of  an  eagle. 

This  was  the  work  of  the  physicist:  then  came  the  con- 
quests of  the  comparative  anatomist  and  physiologist, 
revealing  the  structure  of  every  animal,  and  the  function 
of  every  organ  in  the  whole  biological  series,  from  the 
lowest  zoo4>liyte  up  to  man.-  The  nervous  system  had  been 
made  the  object  of  profound  and  continued  study,  the 
wonderful  and,  at  bottom,  entirely  mysterious  controlling 
power  which  it  exercises  over  the  whole  organism,  physical 
and  mental,  being  recognized  more  and  more.  Thought 
could  not  be  kept  back  from  a  subject  so  profoundly 
suggestive.  Besides  the  physical  life  dealt  with  by  Mr. 
Darwin,  there  is  a  psychical  life  presenting  similar 
gradations,  and  asking  equally  for  a  solution.  How  are 
the  different  grades  and  orders  of  Mind  to  be  accounted 
for?  What  is  the  principle  of  growth  of  that  mysterious 
power  which  on  our  planet  culminates  in  Reason?  These 
are  questions  which,  though  not  thrusting  themselves  so 
forcibly  upon  the  attention  of  the  general  public,  had  not 
only  occupied  many  reflecting  minds,  but  had  been  formally 
broached  by  one  of  them  before  the  "  Origin  of  Species  " 
appeared. 

With  the  mass  of  materials  furnished  by  the  physicist 
and  physiologist  in  his  hands,  Mr.  Herbert  Spencer, 
twenty  years  ago,  sought  to  graft  upon  this  basis  a  system 

*  Dr.  Bertbold  has  shown  that  Leibnitz  had  sound  views  regarding 
the  conservation  of  energy  in  inorganic  nature. 


480  FRAGMENTS  OF  SCIENCE. 

of  psychology;  and  two  years  ago  a  second  and  greatly 
amplified  edition  of  his  work  appeared.  Those  who  have 
occupied  themselves  with  the  beautiful  experiments  of 
Plateau  will  remember  that  when  two  spherules  of  olive-oil 
suspended  in  a  mixture  of  alcohol  and  water  of  the  same 
density  as  the  oil,  are  brought  together,  they  do  not 
immediately  unite.  Something  like  a  pellicle  appears  to 
be  formed  around  the  drops,  the  rupture  of  which  is 
immediately  followed  by  the  coalescence  of  the  globules 
into  one.  There  are  organisms  whose  vital  actions  are 
almost  as  purely  physical  as  the  coalescence  of  such  drops 
of  oil.  They  come  into  contact  and  fuse  themselves  thus 
together.  From  such  organisms  to  others  a  shade  higher, 
from  these  to  others  a  shade  higher  still,  and  on  through 
an  ever-ascending  series,  Mr.  Spencer  conducts  his  argu- 
ment. There  are  two  obvious  factors  to  be  here  taken  into 
account — the  creature  and  the  medium  in  which  it  lives, 
or,  as  it  is  often  expressed,  the  organism  and  its  environ- 
ment. Mr.  Spencer's  fundamental  principle  is,  that  be- 
tween these  two  factors  there  is  incessant  interaction.  The 
organism  is  played  upon  by  the  environment,  and  is 
modified  to  meet  the  requirements  of  the  environment. 
Life  he  defines  to  be  "a  continuous  adjustment  of  internal 
relations  to  external  relations." 

In  the  lowest  organisms  we  have  a  kind  of  tactual  sense 
diffused  over  the  entire  body;  then,  through  "impressions 
from  without  and  their  corresponding  adjustments,  special 
portions  of  the  surface  become  more  responsive  to  stimuli 
than  others.  The  senses  are  nascent,  the  basis  of  all  of 
them  being  that  simple  tactual  sense  which  the  sage  Demo- 
critus  recognized  2,300  years  ago  as  their  common  progen- 
itor. The  action  of  light,  in  the  first  instance,  appears 
to  be  a  mere  disturbance  of  the  chemical  processes  in  the 
animal  organism,  similar  to  that  which  occurs  in  the  leaves 
of  plants.  By  degrees  the  action  becomes  localized  in  a 
few  pigment-cells,  more  sensitive  to  light  than  the  sur- 
rounding tissue.  The  eye  is  incipient.  At  first  it  is  merely 
capable  of  revealing  differences  of  light  and  shade  produced 
by  bodies  close  at  hand.  Followed,  as  the  interception  of 
the  light  commonly  is,  by  the  contact  of  the  closely  ad- 
jacent opaque  body,  sight  in  this  condition  becomes  a 
kind  of  "  anticipatory  touch."  The  adjustment  con- 
tinues; a  slight  bulging  out  of  the  epidermis  over  the 


THE  BEL  FAST  ADDR  ESS.  481 

pigment-granules  supervenes.  A  lens  is  incipient,  and, 
through  the  operation  of  infinite  adjustments,  at  length 
reaches  the  perfection  that  it  displays  in  the  hawk  and 
eagle.  So  of  the  other  senses;  they  are  special  differen- 
tiations of  a  tissue  which  was  originally  vaguely  sensitive 
all  over. 

With  the  development  of  the  senses,  the  adjustments 
between  the  organism  and  its  environment  gradually  extend 
in  space,  a  multiplication  of  experiences  and  a  correspond- 
ing modification  of  conduct  being  the  result.  The  adjust- 
ments also  extend  in  time,  covering  continually  greater 
intervals.  Along  with  this  extension  in  space  and  time 
the  adjustments  also  increase  in  speciality  and  complexity, 
passing  through  the  various  grades  of  brute  life,  and  pro- 
longing themselves  into  the  domain  of  reason.  Very 
striking  are  Mr.  Spencer's  remarks  regarding  the  influence 
of  the  sense  of  touch  upon  the  development  of  intelligence. 
This  is,  so  to  say,  the  mother-tongue  of  all  the  senses, 
into  which  they  must  be  translated  to  be  of  service  to  the 
organism.  Hence  its  importance.  The  parrot  is  the  most 
intelligent  of  birds,  and  its  tactual  power  is  also  greatest. 
From  this  sense  it  gets  knowledge,  unattainable  by  birds 
which  cannot  employ  their  feet  as  hands.  The  elephant 
is  the  most  sagacious  of  quadrupeds — its  tactual  range  and 
slcill,  and  the  consequent  multiplication  of  experiences, 
which  it  owes  to  its  wonderfully  adaptable  trunk,  being 
the  basis  of  its  sagacity.  Feline  animals,  for  a  similar 
cause,  are  more  sagacious  than  hoofed  animals — atonement 
being  to  some  extent  made  in  the  case  of  the  horse,  by  the 
possession  of  sensitive  prehensile  lips.  In  the  Primates_ 
the  evolution  of  intellect  and  the  evolution  of  tactual  ap^~ 
pendages  go  hand  in  hand.  In  the  most  intelligent  an- 
thropoid apes  we  find  the  tactual  range  and  delicacy  greatly 
augmented,  new  avenues  of  knowledge  being  thus  opened 
to  the  animal.  Man  crowns  the  edifice  here,  not  only  in 
virtue  of  his  own  manipulatory  power,  but  through  the 
enormous  extension  of  his  range  of  experience,  by  the 
invention  of  instruments  of  precision,  which  serve  as  sup- 
plemental senses  and  supplemental  limbs.  The  reciprocal 
action  of  these  is  finely  described  and  illustrated.  That 
chastened  intellectual  emotion  to  which  I  have  referred  in 
connection  with  Mr.  Darwin,  is  not  absent  in  Mr.  Spencer. 
His  illustrations  possess  at  times  exceeding  vividness  and 


482  FRAGMENTS  OF  SCIENCE. 

force;  and  from  his  style  on  such  occasions  it  is  to  be 
inferred  that  the  ganglia  of  this  Apostle  of  the  Under- 
standing are  sometimes  the  seat  of  a  nascent  poetic  thrill. 

It  is  a  fact  of  supreme  importance  that  actions,  the 
performance  of  which  at  first  requires  even  painful  effort 
and  deliberation,  may,  by  habit,  be  rendered  automatic. 
Witness  the  slow  learning  of  its  letters  by  a  child,  and  the 
subsequent  facility  of  reading  in  a  man,  when  each  group 
of  letters  which  forms  a  word  is  instantly,  and  without 
effort,  fused  to  a  single  perception.  Instance  the  billiard- 
player,  wliose  muscles  of  hand  and  eye,  when  he  readies 
the  perfection  of  his  art,  are  unconsciously  co-ordinated. 
Instance  the  musician,  who,  by  practice,  is  enabled  to  fuse 
a  multitude  of  arrangements,  auditory,  tactual  and  mus- 
cular, into  a  process  of  automatic  manipulation.  Combin- 
ing such  facts  with  the  doctrine  of  hereditary  transmission, 
we  reach  a  theory  of  Instinct.  A  chick,  after  coming  out 
of  the  egg,  balances  itself  correctly,  runs  about,  picks  up 
food,  thus  showing  that  it  possesses  a  power  of  directing 
its  movements  to  definite  ends.  How  did  the  chick  learn 
this  very  complex  co-ordination  of  eyes,  muscles,  and  beak? 
It  has  not  been  individually  taught;  its  personal  experience 
is  nil;  but  it  has  the  benefit  of  ancestral  experience.  Jji 
its  inherited  organization  are  registered  the  powers  which 
it  displays  at  birth.  So  also  as  regards  the  instinct  of  the 
hive-bee,  already  referred  to.  The  distance  at  which  the 
insects  stand  apart  when  they  sweep  their  hemispheres  and 
build  their  cells  is  "organically  remembered."  Man  also 
carries  with  him  the  physical  texture  of  his  ancestry,  as 
well  as  the  inherited  intellect  bound  up  with  it.  The  defects 
of  intelligence  during  infancy  and  youth  are  probably  less 
due  to  a  lack  of  individual  experience,  than  to  the  fact 
that  in  early  life  the  cerebral  organization  is  still  incom- 
plete. The  period  necessary  for  completion  varies 
with  the  race,  and  with  the  individual.  As  a  round  shot 
outstrips  the  rifled  bolt  on  quitting  the  muzzle  of  the  gun, 
so  the  lower  race,  in  childhood,  may  outstrip  the  higher. 
But  the  higher  eventually  overtakes,  the  lower,  and 
surpasses  it  in  range.  As  regards  individuals,  we  do  not 
always  find  the  precocity  of  youth  prolonged  to  mental 
power  in  maturity;  while  the  dullness  of  boyhood  is  some- 
times strikingly  contrasted  with  the  intellectual  energy  of 
after  years.  Newton,  when  a  boy,  was  weakly,  and  he 


THE  BELFAST  ADDRESS.  483 

showed  no  particular  aptitude  at  school;  but  in  his 
eighteenth  year  he  went  to  Cambridge,  and  soon  after- 
ward astonished  his  teachers  by  his  power  of  dealing  with 
geometrical  problems.  During  his  quiet  youth  his  brain 
was  slowly  preparing  itself  to  be  the  organ  of  those  energies 
which  he  subsequently  displayed. 

By  myriad  blows  (to  use  a  Lucretian  phrase)  the  image 
and  superscription  of  the  external  world  are  stamped  as  /  fin, , 
states  of  consciousness  upon  the  organism,  the  depth  of 
the  impression  depending  on  the  number  of  the  blows. 
When  two  or  more  phenomena  occur  in  the  environment 
invariably  together,  they  are  stamped  to  the  same  depth 
or  to  the  same  relief,  and  indissolubly  connected.  And 
here  we  come  to  the  threshold  of  a  great  question.  Seeing 
that  he  could  in  no  way  rid  himself  of  the  consciousness  of 
Space  and  Time,  Kant  assumed  them  to  be  necessary 
"  forms  of  intuition,"  the  molds  and  shapes  into  which 
our  intuitions  are  thrown,  belonging  to  ourselves,  and 
without  objective  existence.  With  unexpected  power  and 
success,  Mr.  Spencer  brings  the  hereditary  experience 
theory,  as  he  holds  it,  to  bear  upon  this  question.  "  If 
there  exist  certain  external  relations  which  are  experienced 
by  all  organisms  at  all  instants  of  their  waking  lives — rela- 
tions which  are  absolutely  constant  and  universal — there 
will  be  established  answering  internal  relations,  that  are 
absolutely  constant  and  universal.  Such  relations  we 
have  in  those  of  Space  and  Time.  As  the  substratum 
of  all  other  relations  of  the  Non-ego,  they  must  be  re- 
sponded to  by  conceptions  that  are  the  substrata  of  all 
other  relations  in  the  Ego.  Being  the  constant  and  infi- 
nitely repeated  elements  of  thought,  they  must  become  the 
automatic  elements  of  thought — the  elements  of  thought 
which  it  is  impossible  to  get  rid  of — the  "forms  of 
intuition." 

Throughout  this  application  and  extension  of  Hartley's 
and  Mill's  "  Law  of  Inseparable  Association,"  Mr. 
Spencer  stands  upon  his  own  ground,  invoking,  instead  of 
the  experiences  of  the  individual,  the  registered  experiences 
of  the  race.  His  overthrow  of  the  restriction  of  experience 
to  the  individual  is,  I  think,  complete.  That  restriction 
ignores  the  power  of  organizing  experience,  furnished  at 
the  outset  to  each  individual;  it  ^ignores  the  different 
degrees  of  this  power  possessed  by  different  races,  and  by 


484  FRAGMENTS  OF  SCIENCE. 

different  individuals  of  the  same  race.  AYere  there  not  in 
the  human  brain  a  potency  antecedent  to  all  experience, 
a  dog  or  a  calf  ought  to  be  as  capable  of  education  as  a 
man.  These  predetermined  internal  relations  are  inde- 
pendent of  the  experiences  of  the  individual.  The  human 
brain  is  the  "organized  register  of  infinitely  numerous 
experiences  received  during  the  evolution  of  life,  or  rather 
during  the  evolution  of  that  series  of  organisms  through 
which  the  human  organism  has  been  reached.  The  effects 
of  the  most  uniform  and  frequent  of  these  experiences  have 
been  successively  bequeathed,  principal  and  interest,  and 
have  slowly  mounted  to  that  high  intelligence  which  lies 
latent  in  the  brain  of  the  infant.  Thus  it  happens  that  the 
European  inherits  from  twenty  to  thirty  cubic  inches  more 
of  brain  than  the  Papuan.  Thus  it  happens  that  faculties, 
as  of  music,  which  scarcely  exist  in  some  inferior  races, 
become  congenital  in  superior  ones.  Thus  it  happens  that 
out  of  savages  unable  to  count  up  to  the  number  of  their 
fingers,  and  speaking  a  language  containing  only  nouns 
and  verbs,  arise  at  length  our  Newtons  and  Shakspeares." 

SECTION  8. — At  the  outset  of  this  address  it  was  stated 
that  physical  theories^ wEIcTi  He~beyond  experience  are 
derived  by  a  process  of  abstraction  from  experience.  It  is 
instructive  to  note  from  this  point  of  view  the  successive 
introduction  of  new  conceptions.  The  idea  of  the  attrac- 
tion of  gravitation  was  preceded  by  the  observation  of  the 
attraction  of  iron  by  a  magnet,  and  of  light  bodies  by 
rubbed  amber.  The  polarity  of  magnetism  and  electricity 
also  appealed  to  the  senses.  It  thus  became  the  sub- 
stratum of  the  conception  that  atoms  and  molecules  are 
endowed  with  attractive  and  repellent  poles,  by  the  play 
of  which  definite  forms  of  crystalline  architecture  are  pro- 
duced. Thus  molecular  force  becomes  structural.*  It 
required  no  great  boldness  of  thought  to  extend  its  play 
into  organic  nature,  and  to  recognize  in  molecular  force 
the  agency  by  which  both  plants  and  animals  are  built 
up.  In  this  way,  out  of  experience  arise  conceptions  which 
are  wholly  ultra-experiential)./  None  of  the  atomists  of  antiq- 
uity had  any  notion  of  this  play  of  molecular  polar  force, 
but  they  had  experience  of  gravity,  as  manifested  by  fall- 

*  See  Art.  on  Matter  and  Force,  or  "  Lectures  ou  Light,"  No,  HI, 


THE  E  EL  FA  ST  A  DDR  ESS.  485 

ing  bodies.  Abstracting  from  this,  they  permitted  their 
atoms  to  fall  eternally  through  empty  space.  Democritus 
assumed  that  the  larger  atoms  moved  more  rapidly  than 
the  smaller  ones,  which  they  therefore  could  overtake,  and 
with  which  tney  could  combine.  Epicurus,  holding  that 
empty  space  could  offer  no  resistance  to  motion,  .ascribed 
to  all  the  atoms  the  same  velocity:  but  he  seems  to  have 
overlooked  the  consequence  that  under  such  circumstances 
the  atoms  could  never  combine.  Lucretius  cut  the  knot 
by  quitting  the  domain  of  physics  altogether,  and  causing 
the  atoms  to  move  together  by  a  kind  of  volition. 

Was  the  instinct  utterly  at  fault  which  caused  Lucretius 
thus  to  swerve  from  his  own  principles?  Diminishing 
gradually  the  number  of  progenitors,  Mr.  Darwin  comes  at 
length  to  one  "  primordial  form;  "  but  he  does  not  say,  so 
far  as  I  remember,  how  he  supposes  this  form  to  have  been 
introduced.  He  quotes  with  satisfaction  the  words  of  a 
celebrated  author  and  divine  who  had  "gradually  learned  to 
see  that  it  was  just  as  noble  a  conception  of  the  Deity  to 
believe  He  created  a  few  original  forms,  capable  of  self- 
development  into  other  and  needful  forms,  as  to  believe 
He  required  a  fresh  act  of  creation  to  supply  the  voids 
caused  by  the  action  of  his  laws."  What  Mr.  Darwin 
thinks  of  this  view  of  the  introduction  of  life,  I  do  not 
•know.  But  the  anthropomorphism,  which  it- seemed  his 
object  to  set  aside,  is  as  firmly  associated  with  the  creation 
of  a  few  forms  as  with  the  creation  of  a  multitude.  We 
need  clearness  and  thoroughness  here.  Two  courses  and 
two  only  are  possible.  Either  let  us  open  our  doors 
freely  to  the  conception  of  creative  acts,  or  abandoning 
them,  let  us  radically  change  our  notions  of  Matter.  If 
we  look  at  matter  as  pictured  by  Democritus,  and  as  de- 
lined  for  generations  in  our  scientific  text-books,  the 
notion,  of  conscious  life  coming  out  of  it  cannot  be  formed 
by  the  mind.  The  argument  placed  in  the  mouth  of 
Bishop  Butler  suffices,  in  my  opinion,  to  crush  all  such 
materialism  as  this.  Those,  however,  who  framed  these 
definitions  of  matter  were  but  partial  students.  They 
were  not  biologists,  but  mathematicians,  whose  labors 
referred  only  to  such  accidents  and  properties  of  matter 
as  could  be  expressed  in  their  formula?.  Their  science  was 
mechanical  science,  not  the  science  of  life.  With  matter 
in  its  wholeness  they  never  dealt;  and,  denuded  by  their 


486  FRA  QMENTS  0 F  SCIENCE. 

imperfect  definitions.  "  the  gentle  mother  of  all  "became 
the  object  of  her  children's  dread.  Let  us  reverently,  but 
honestly,  look  the  question  in  the  face.  Divorced  from 
matter,  where  is  life?  Whatever  our  faith  may  say,  our 
knowledge  shows  them  to  be  indissolubly  joined.  Every 
meal  we  eat,  and  every  cup  we  drink,  illustrates  the 
mysterious  control  of  Mind  by  Matter. 

On  tracing  the  line  of  life  backward,  we  see  it  approach- 
ing more  and  more  to  what  we  call  the  purely  physical 
condition.  We  come  at  length  to  those  organisms  which  I 
have  compared  to  drops  of  oil  suspended  in  a  mixture  of 
alcohol  and  water.  We  reach  the  protogenes  of  Haeckel, 
in  which  we  have  "  a  type  distinguishable  from  a  fragment 
of  albumen  only  by  its  finely  granular  character."  Can  we 
pause  here?  We  break  a  magnet,  and  find  two  poles  in 
each  of  its  fragments.  We  continue  the  process  of  break- 
ing; but,  however  small  the  parts,  each  carries  with  it, 
though  enfeebled,  the  polarity  of  the  whole.  And  when 
we  can  break  no  longer,  we  prolong  the  intellectual  vision 
to  the  polar  molecules.  Are  we  not  urged  to  do  something 
similar  in  the  case  of  life?  Is  there  not  a  temptation  to 
close  to  some  extent  with  Lucretius,  when  he  affirms  that 
"  Nature  is  seen  to  do  all  things  spontaneously  of  herself 
without  the  meddling  of  the  gods?"  or  with  Bruno,  when 
he  declares  that  Matter  is  not  "  that  mere  empty  capacity, 
which  philosophers  have  pictured  her  to  be,  but  the 
universal  mother  who  brings  forth  all  things  as  the  fruit 
of  her  own  womb?"  Believing,  as  I  do,  in  the  continuity 
of  nature,  I  cannot  stop  abruptly  where  our  microscopes 
cease  to  be  of  use.  Here  the  vision  of  the  mind  author- 
itatively supplements  the  vision  of  the  eye.  By  a  necessity 
engendered  and  justified  by  science  I  cross  the  boundary 
of  the  experimental  evidence,*  and  discern  in  that  Matter 
which  we,  in  our  ignorance  of  its  latent  powers,  and  not- 
withstanding our  professed  reverence  for  its  Creator,  have 
hitnerto  covered  with  opprobrium,  the  promise  and  potency 
of  all  terrestrial  Life. 

If  you  ask  me  whether  there  exists  the  least  evidence  to 
prove  that  any  form  of  life  can  be  developed  out  of 
matter,  without  demonstrable  antecedent  life,  my  reply  is 
that  evidence  considered  perfectly  conclusive  by  many  has 

*  This  mode  of  procedure  was  not  invented  in  Belfast. 


TiffK  BELFAST  ADDRK88.  48? 

been  adduced;  and  that  were  some  of  us  who  have  pon- 
dered this  question  to  follow  a  very  common  example,  and 
accept  testimony  because  it  falls  in  with  our  belief,  we  also 
should  eagerly  close  with  the  evidence  referred  to.  But 
there  is  in  the  true  man  of  science  a  desire  stronger  than 
the  wish  to  have  his  beliefs  upheld;  namely,  the  desire  to 
have  them  true.  And  this  stronger  wish  causes  him  to 
reject  the  most  plausible  support,  if  he  has  reason  to 
suspect  that  it  is  vitiated  by  error.  Those  to  whom  I 
refer  as  having  studied  this  question,  believing  the  evidence 
offered  in  favor  of  "  spontaneous  generation  "  to  be  thus 
vitiated,  cannot  accept  it.  They  know  full  well  that  the 
chemist  now  prepares  from  inorganic  matter  a  vast  array 
of  substances,  which  were  some  time  ago  regarded  as  the 
sole  products  of  vitality.  They  are  intimately  acquainted 
with  the  structural  power  of  matter,  as  evidenced  in  the 
phenomena  of  crystallization.  They  can  justify  scien- 
tifically their  belief  in  its  potency,  under  the  proper  con- 
ditions, to  produce  organisms.  But,  in  reply  to  your 
question,  they  will  frankly  admit  their  inability  to  point 
to  any  satisfactory  experimental  proof  that  life  can  be 
developed,  save  from  demonstrable  antecedent  life.  As 
already  indicated,  they  draw  the  line  from  the  highest 
organisms  through  lower  ones  down  to  the  lowest;  and  it 
is  the  prolongation  of  this  line  by  the  intellect,  beyond  the 
range  of  the  senses,  that  leads  them  to  the  conclusion 
which  Bruno  so  boldly  enunciated.* 

The  "  materialism "  here  professed  may  be  vastly 
different  from  what  you  suppose,  and  I  therefore  crave 
your  gracious  patience  to  the  end".  "  The  question  of  an 
external  world,"  says  J.  S.  Mill,  "  is  the  great  battle-ground 
of  metaphysics. "f  Mr.  Mill  himself  reduces  external 
phenomena  to  "  possibilities  of  sensation."  Kant,  as  we 
have  seen,  made  time  and  space  "forms"  of~~bur  own 
intuitions.  Fichte,  having  first  by  the  inexorable  logic  of 
his  understanding  proved  himself  to  be  a  mere  link  in 
that  chain  of  eternal  causation  which  holds  so  rigidly  in 
nature,  violently  broke  the  chain  by  making  nature,  and 
all  that  it  inherits,  an  apparition  of  the  mind.  J  And  it  is 

*  Bruno  was  a  "  Pantheist,"  not  an  "  Atheist "  or  a  "  Materialist." 
f  "  Examination  of  Hamilton,"  p.  154. 
$"  Bestiinrnung  des  Menschen." 


488  fR A  OMENTS  0  F  SCTENCE. 

by  no  means  easy  to  combat  such  notions.  For  when  I 
say  "  I  see  you,"  and  that  there  is  not  the  least  doubt 
about  it,  the  obvious  reply  is,  that  what  I  am  really  con- 
scious of  is  an  affection  of  my  own  retina.  And  if  I  urge 
that  my  sight  can  be  checked  by  touching  you,  the  retort 
would  be  that  I  am  equally  transgressing  the  limits  of  fact; 
for  what  I  am  really  conscious  of  is,  not  that  you  are 
there,  but  that  the  nerves  of  my  hand  have  undergone  a 
change.  All  we  hear,  and  see,  and  touch,  and  taste,  and 
smell,  are,  it  would  be  urged,  mere  variations  of  our  own 
condition,  beyond  which,  even  to  the  extent  of  a  hair's 
breadth,  we  cannot  go.  That  anything  answering  to  our 
impressions  exists  outside  of  ourselves  is  not  'A  fact,  but 
an  inference,  to  which  all  validity  would  be  denied  by  an 
idealist  like  Berkeley,  or  by  a  skeptic  like  Hume.  Mr. 
Spencer  takes  another  line.  With  him,  as  with  the 
uneducated  man,  there  is  no  doubt  or  question  as  to  the 
existence  of  an  external  world.  But  he  differs  from  the 
uneducated,  who  think  that  the  world  really  is  what  con- 
sciousness represents  it  to  be.  Our  states  of  consciousness 
are  mere  symbols  of  an  outside  entity  which  produces  them 
and  determines  the  order  of  their  succession,  but  the  real 
nature  of  which  we  can  never  know.*  In  fact,  the  whole 
process  of  evolution  is  the  manifestation  of  a  Power 
absolutely  inscrutable  to  the  intellect  of  man.  As  little  in 
our  day  as  in  the  days  of  Job  can  man  by  searching  find 
this  Power  out.  Considered  fundamentally,  then,  it  is  by 
the  operation  of  an  insoluble  mystery  that  life  on  earth  is 
evolved,  species  differentiated,' and  mind  unfolded,  from 
their  prepotent  elements  in  the  immeasurable  past. 

*  In  a  paper,  at  once  popular  and  profound,  entitled  "Recent 
Progress  in  the  Theory  of  Vision,"  contained  in  the  volume  of  lec- 
tures by  Heimholtz,  published  by  Longmans,  this  symbolism  of  our 
states  of  consciousness  is  also  dwelt  upon.  The  impressions  of  sense 
are  the  mere  signs  of  external  things.  In  this  paper  Heimholtz  con- 
tends strongly  against  the  view  that  the  consciousness  of  space  is 
inborn;  and  he  evidently  doubts  the  power  of  the  chick  to  pick  up 
grains  of  corn  without  preliminary  lessons.  On  this  point,  he  says, 
further  experiments  are  needed.  Such  experiments  have  been  since 
made  by  Mr.  Spalding,  aided,  I  believe,  in  some  of  his  observations 
by  the  accomplished  and  deeply  lamented  Lady  Amberly;  and  they 
seem  to  prove  conclusively  that  the  chick  does  not  need  a  single 
moment's  tuition  to  enable  it  to  stand,  run,  govern  the  muscles  of  its 
eyes,  and  peck.  Heimholtz,  however,  is  contending  against  the 
notion  of  pre-established  harmony;  and  I  am  not  aware  of  his  views 
as  to  the  organization  of  experiences  of  race  or  breed. 


TEE  BELFAST  ADDRESS.  439 

The  strength  of  the  doctrine  of  evolution  consists,  not 
in  an  experimented  demonstration  (for  the  subject  is 
hardly  accessible  to  this  mode  of  proof),  but  in  its  general 
harmony  with  scientific  thought.  From  contrast,  more- 
over, it  derives  enormous  relative  cogency.  On  the  one 
side  we  have  a  theory  (if  it  could  with  any  propriety  be  so 
called)  derived,  as  were  the  theories  referred  to  at  the 
beginning  of  this  address,  not  from  the  study  of  nature, 
but  from  the  observation  of  men — a  theory  which  converts 
the  Power  whose  garment  is  seen  in  the  visible  universe  into 
an  Artificer,  fashioned  after  the  human  model,  and  acting  by 
broken  efforts  as  man  is  seen  to  act.  On  the  other  side  we 
have  the  conception  that  all  we  see  around  us,  and  all  we  feel 
within  us — the  phenomena  of  physical  nature  as  well  as 
those  of  the  human  mind — have  their  unsearchable  roots  in 
a  cosmical  life,  if  I  dare  apply  the  term,  an  infinitesimal 
span  of  which  is  offered  to  the  investigation  of  man.  And 
even  this  span  is  only  knowable  in  part.  We  can  trace  the 
development  of  a  nervous  system,  and  correlate  with  it  the 
parallel  phenomena  of  sensation  and  thought.  We  see 
with  undoubting  certainty  that  they  go  hand  in  hand. 
But  we  try  to  soar  in  a  vacuum  the  moment  we  seek  to 
comprehend  the  connection  between  them.  An  Archi- 
medean fulcrum  is  here  required  which  the  human  mind 
cannot  command;  and  the  effort  to  solve  the  problem — to 
borrow  a  comparison  from  an  illustrious  friend  of  mine — 
is  like  that  of  a  man  trying  to  lift  himself  by  his  own 
waistband.  All  that  has  been  said  in  this  discourse  is  to 
be  taken  in  connection  with  this  fundamental  truth. 
When  "nascent  senses"  are  spoken  of,  when  "the  dif- 
ferentiation of  a  tissue  at  first  vaguely  sensitive  all  over" 
is  spoken  of,  and  when  these  possessions  and  processes  are 
associated  with  "the  modification  of  an  organism  by  its 
environment,"  the  same  parallelism,  without  contact,  or 
even  approach  to  contact,  is  implied.  Man  the  object  is 
separated  by  an  impassable  gulf  from  man  the  subject. 
There  is  no  motor  energy  in  the  human  intellect  to  carry 
it  without  logical  rupture,  from  the  one  to  the  other. 


SECTION  9. — The  doctrine  of  evolution  derives  man,  in 
his  totality,  from  the  interaction  of  organism  and  environ- 
ment through  countless  ages  past.  The  human  under- 
standing, for  example — that  faculty  which  Mr.  Spencer 


4 90  FRA  GMENTS  OF  SCIENCE. 

has  turned  so  skillfully  round  upon  its  own  antecedents — 
is  itself  a  result  of  the  play  between  organism  and  environ- 
ment through  cosmic  ranges  of  time.  Never,  surely,  did 
prescription  plead  so  irresistible  a  claim.  But  then  it 
comes  to  pass  that,  over  and  above  his  understanding, 
there  are  many  other  things  appertaining  to  man,  whose 
prescriptive' rights  are  quite  as  strong  as  those  of  the  under- 
standing itself.  It  is  a  result,  for  example,  of  the  play  of 
organism  and  environment  that  sugar  is  sweet,  and  that 
aloes  are  bitter;  that  the  smell  of  henbane  differs  from  the 
perfume  of  a  rose.  Such  facts  of  consciousness  (for  which, 
by  the  way,  no  adequate  reason  has  ever  been  rendered) 
are  quite  as  old  as  the  understanding;  and  many  other 
things  can  boast  an  equally  ancient  origin.  Mr.  Spencer 
at  one  place  refers  to  that  most  powerful  of  passions — the 
amatory  passion — as  one  which,  when  it  first  occurs,  is 
antecedent  to  all  relative  experience  whatever;  and  we  may 
press  its  claim  as  being  at  least  as  ancient,  and  as  valid, 
as  that  of  the  understanding  itself.  Then  there  are  such 
things  woven  into  the  texture  of  man  as  the  feeling  of  awe, 
reverence,  wonder — and  not  alone  the  sexual  love  just 
referred  to,  but  the  love  of  the  beautiful,  physical,  and 
moral,  in  nature,  poetry,  and  art.  There  is  also  that 
deep- set  feeling,  which  since  the  earliest  dawn  of  history, 
and  probably  for  ages  prior  to  all  history,  incorporated 
itself  in  the  religions  of  the  world.  You,  who  have 
escaped  from  these  religions  into  the  high-and-dry  light  of 
the  intellect,  may  deride  them;  but  in  so  doing  you  deride 
accidents  of  form  merely,  and  fail  to  touch  the  immovable 
basis  of  the  religious  sentiment  in  the  nature  of  man.  To 
yield  this  sentiment  reasonable  satisfaction  is  the  problem 
of  problems  at  the  present  hour.  And  grotesque  in  rela- 
tion to  scientific  culture  as  many  of  the  religions  of  the 
world  have  been  and  are — dangerous,  nay,  destructive,  to 
the  dearest  privileges  of  freemen  as  some  of  them  un- 
doubtedly have  been,  and  would,  if  they  could,  be  again — 
it  will  be  wise  to  recognize  them  as  the  forms  of  a  force, 
mischievous  if  permitted  to  intrude  on  the  region  of 
objective  knowledge,  over  which  it  holds  no  command,  but 
capable  of  adding,  in  the  region  of  poetry  and  emotion, 
inward  completeness  and  dignity  to  man. 

Feeling,  I  say  again,  dates  from  as  old  an  origin  and  as 
high  a  source  as  intelligence,  and  it  equally  demands  its 


THE  B  EL  FAS?  ADDRESS.  49 1 

range  of  play.  The  wise  teacher  of  humanity  will  recognize 
the  necessity  of  meeting  this  demand,  rather  than  of  resist- 
ing it  on  account  of  errors  and  absurdities  of  form.  What 
we  should  resist,  at  all  hazards,  is  the  attempt  made  in  the 
past,  and  now  repeated,  to  found  upon  this  elemental  bias 
of  man's  nature  a  system  which  should  exercise  despotic 
sway  over  his  intellect.  1  have  no  fear  of  such  a  consum- 
mation. Science  has  already  to  some  extent  leavened  the 
world;  it  will  leaven  it  more  and  more.  I  should  look 
upon  the  mild  light  of  science  breaking  in  upon  the  minds 
of  the  youth  of  Ireland,  andstrengthenirig,gradually  to  the 
perfect  day,  as  a  surer  check  to  any  intellectual  or  spiritual 
tyranny  which  may  threaten  this  island,  than  the  laws  of 
princes  or  the  swords  of  emperors.  We  fought  and  won 
our  battle  even  in  the  middle  ages:  should  we  doubt  the 
issue  of  another  conflict  with  our  broken  foe? 

The  impregnable  position  of  science  may  be  described  in 
a  few  words.  We  claim,  and  we  shall  wrest  from  theology, 
the  entire  domain  of  cosmological  theory.  All  schemes 
and  systems  which  thus  infringe  upon  the  domain  of 
science  must,  in  so  far  as  they  do  this,  submit  to  its  con- 
trol, and  relinquish  all  thought  of  controlling  it.  Acting 
otherwise  proved  always  disastrous  in  the  past,  and  it  is 
simply  fatuous  to-day.  Every  system  which  would  escape 
the  fate  of  an  organism  too  rigid  to  adjust  itself  to  its 
environment,  must  be  plastic  to  the  extent  that  the  growth 
of  knowledge  demands.  When  this  truth  has  been 
thoroughly  taken  in,  rigidity  will  be  relaxed,  exclusiveness 
diminished,  things  now  deemed  essential  will  be  dropped, 
and  elements  now  rejected  will  be  assimilated.  The  lifting 
of  the  life  is  the  essential  point;  and  as  long  as  dogmatism, 
fanaticism,  and  intolerance  are  kept  out,  various  modes  of 
leverage  may  be  employed  to  raise  life  to  a  higher  level. 

Science  itself  not  unfrequently  derives  motive  power 
from  an  ultra-scientific  source.  Some  of  its  greatest  dis- 
coveries have  been  made  under  the  the  stimulus  of  a  non- 
scientific  ideal.  This  was  the  case  among  the  ancients, 
and  it  has  been  so  among  ourselves.  Mayer,  Joule,  and 
Coldjug,  whose  names  are  associated  with  The  greatest  of 
modern  generalizations,  were  thus  influenced.  With  his 
usual  insight,  Lange  at  one  place  remarks,  that  "  it  is  not 
always  the  objectively  correct  and  intelligible  that  helps 
man  most,  or  leads  most  quickly  to  the  fullest  and  truest 


492  FRAGMENTS  Of1  SCItiNCti. 

knowledge.  As  the  sliding  body  upon  the  brachvjstochrone 
reaches  its  end  sooner  than  by  the  straighter  road  of  the 
inclined  plane,  so,  through  the  swing  of  the  ideal,  we 
often  arrive  at  the  naked  truth  more  rapidly  than  by  the 
processes  of  the  understanding."  Whewell  speaks  of 
enthusiasm  of  temper  as  a  hindrance  to  science;  but  he 
means  the  enthusiasm  of  weak  heads.  There  is  a  strong 
and  resolute  enthusiasm  in  which  science  finds  an  ally; 
and  it  is  to  the  lowering  of  this  fire,  rather  than  to  the 
diminution  of  intellectual  insight,  that  the  lessening  pro- 
ductiveness of  men  of  science,  in  their  mature  years,  is  to 
be  ascribed.  Mr.  Buckle  sought  to  detach  intellectual 
achievement  from  moral  force.  He  gravely  erred,  for 
without  moral  force  to  whip  it  into  action,  the  achievement 
of  the  intellect  would  be  poor  indeed. 

(  It  has  been  said  by  its  opponents  that  science  divorces 
/itself  from  literature;  but  the  statement,  like  so  many 
Bothers,  arises  from  lack  of  knowledge.  A  glance  at  the 
Jess  technical  writings  of  its  leaders — of  its  Helmholtz,  its 
Huxley,  and  its  Du  Bois-Eeymond — would  show  what 
breadth  of  literary  culture  they  command.  Where  among 
modern  writers  can  you  find  their  superiors  in  clearness 
and  vigor  of  literary  style?  Science  desires  not  isolation, 
but  freely  combines  with  every  effort  toward  the  bettering 
of  man's  estate.  Single-handed,  and  supported,  not  by 
outward  sympathy,  but  by  inward  force,  it  has  built  at 
least  one  great  wing  of  the  many-mansioned  home  which 
man  in  his  totality  demands.  And  if  rough  walls  and  pro- 
truding rafter-ends  indicate  that  on  one  side  the  edifice  is 
still  incomplete,  it  is  only  by  wise  combination  of  the 
parts  required,  with  those  already  irrevocably  built,  that 
we  can  hope  for  completeness.  There  is  no  necessary 
incongruity  between  what  has  been  accomplished  and  what 
remains  to  be  done.  The  moral  glow  of  Socrates,  which 
we  all  feel  by  ignition,  has  in  it  nothing  incompatible 
with  the  physics  of  Anaxagoras  which  he  so  much  scorned, 
but  which  he  would  hardly  scorn  to-day.  And  here  I  am 
reminded  of  one  among  us,  hoary,  but  still  strong,  whose 
prophet-voice  some  thirty  years  ago,  far  more  than  any 
other  of  this  age,  unlocked  whatever  of  life  and  nobleness 
lay  latent  in  its  most  gifted  minds — one  fit  to  stand  beside 
Socrates  or  the  Maccabean  Eleazar,  and  to  dare  and  suffer 
all  that  they  suffered  and  dared — fit,  as  he  once  said  of 


THE  BEL  FA  ST  A  D DRESS,  493 

Fichte,  "  to  have  been  the  teacher  of  the  Stoa,  and  to  have 
discoursed  of  Beauty  and  Virtue  in  the  groves  of  Academe." 
With  a  capacity  to  grasp  physical  principles  which  his 
friend  Goethe  did  not  possess,  and  which  even  total  lack  of 
exercise  has  not  been  able  to  reduce  to  atrophy,  it  is  the 
world's  loss  that  he,  in  the  vigor  of  his  years,  did  not  open 
his  mind  and  sympathies  to  science,  and  rttake  its  con- 
clusions a  portion  of  his  message  to  mankind.  Mar- 
velously  endowed  as  he  was — equally  equipped  on  the  side 
of  the  heart  and  of  the  understanding — he  might  have 
done  much  toward  teaching  us  how  to  reconcile  the  claims 
of  both,  and  to  enable  them  in  coming  times  to  dwell  to- 
gether, in  unity  of  spirit  and  in  the  bond  of  peace. 

And  now  the  end  is  come.  With  more  time,  or  greater 
strength  and  knowledge,  what  has  been  here  said  might 
have  been  better  said,  while  worthy  matters,  here  omitted, 
might  have  received  fit  expression.  But  there  would  have 
been  no  material  deviation  from  the  views  set  forth.  As 
regards  myself,  they  are  not  the  growth  of  a  day;  and  as 
regards  you,  I  thought  you  ought  to  know  the  environment 
which,  with  or  without  your  consent,  is  rapidly  surrounding 
you,  and  in  relation  to  which  some  adjustment  on  your 
part  may  be  necessary.  A  hint  of  Hamlet's,  however, 
teaches  us  how  the  troubles  of  common  life  may  be  ended; 
and  it  is  perfectly  possible  for  you  and  me  to  purchase 
intellectual  peace  at  the  price  of  "intellectual  death.  The 
world  is  not  without  refuges  of  this  description;  nor  is  it 
wanting  in  persons  who  seek  their  shelter,  and  try  to 
persuade  others  to  do  the  same.  The  unstable  and  the 
weak  Have  yielded  and  will  yield  to  this  persuasion,  and 
they  to  whom  repose  is  sweeter  than  the  truth.  But  I 
.would  exhort  you  to  refuse  the  offered  shelter,  and  to  scorn 
the  base  repose — to  accept,  if  the  choice  be  forced  upon 
you,  commotion  before  stagnation,  the  breezy  leap  of  the 
torrent  before  the  foetid  stillness  of  the  swamp.  In  the 
course  of  this  address  I  have  touched  on  debatable  ques- 
tions, and  led  you  over  what  will  be  deemed  dangerous 
ground — and  this  partly  with  the  view  of  telling  you  that, 
as  regards  these  questions,  science  claims  unrestricted  right 
of  search.  It  is  not  to  the  point  to  say  that  the  views  of 
Lucretius  and  Bruno,  of  Darwin  and  Spencer,  may  be 
wrong.  Here  I  should  agree  with  you,  deeming  it  indeed 


494  FRAGMENTS  OF  SCIENCE. 

certain  that  these  views  will  undergo  modification.  But 
the  point  is,  that,  whether  right  or  wrong,  we  claim  the 
right  to  discuss  them.  For  science,  however,  no  ex- 
clusive claim  is  here  made;  you  are  not  urged  to  erect  it 
into  an  idol.  The  inexorable  advance  of  man's  under- 
standing in  the  path  of  knowledge,  and  those  unquenchable 
claims  of  his  moral  and  emotional  nature,  which  the 
understanding  can  never  satisfy,  are  here  equally  set  forth. 
The  world  embraces  not  only  a  Newton,  but  a  Shakespeare 
— not  only  a  Boyle,  but  a  Raphael — not  only  a  Kant,  but  a 
Beethoven — not  only  a  Darwin,  but  a  Carlyle.  Not  in 
each  of  these,  but  in  all,  is  human  nature  whole.  They 
are  not  opposed,  but  supplementary — not  mutually  ex- 
clusive, but  reconcilable.  And  if,  unsatisfied  with  them 
all,  the  human  mind,  with  the  yearning  of  a  pilgrim  for 
his  distant  home,  will  still  turn  to  the  mystery  from  which 
it  has  emerged,  seeking  so  to  fashion  it  as  to  give  unity  to 
thought  and  faith;  so  long  as  this  is  done,  not  only  with- 
out intolerance  or  bigotry  of  any  kind,  but  with  the 
enlightened  recognition  that  ultimate  fixity  of  conception 
is  here  unattainable,  and  that  each  succeeding  age  must  be 
held  free  to  fashion  the  mystery  in  accordance  with  its  own 
needs — then,  casting  aside  all  the  restrictions  of  materialism, 
I  would  affirm  this  to  be  a  field  for  the  noblest  exercise  of 
what,  in  contrast  with  the  knowing  faculties,  may  be 
called  the  creative  faculties  of  man.  Here,  however,  I 
touch  a  theme  too  great  for  me  to  handle,  but  which  will 
assuredly  be  handled  by  the  loftiest  minds,  when  you  and 
I,  like  streaks  of  morning  cloud,  shall  have  melted  into 
the  infinite  azure  of  the  past. 


CHAPTER  XXXII. 

APOLOGY   FOR  THE   BELFAST    ADDRESS.       1874. 

THE  WORLD  has  been  frequently  informed  of  late  that  I 
have  raised  up  against  myself  a  host  of  enemies;  and  con- 
sidering, with  few  exceptions,  the  deliverances  of  the 
Press,  and  more  particularly  of  the  religious  Press,  I  am 
forced  to  admit  that  the  statement  is  only  too  true.  I 
derive  some  comfort,  nevertheless,  from  the  reflection  of 
Diogenes,  transmitted  to  us  by  Plutarch,  that  "he.  who 


.. 


• 

APOLOGY  FOR  THE  BELFAST  ADDRESS.         495 

would  be  saved  must  have  good  friends  or  violent  enemies; 
aml"thlit  "he  is^besToff^vvlio  possesses  both."  This  "best" 
condition,  I  have  reason  to  believe,  is  mine. 

'Reflecting  on  the  fraction  I  have  read  of  recent  remon- 
strances, appeals,  menaces,  and  judgments — covering  not 
only  the  world  that  now  is,  but  that  which  is  to  come — I  -  V-i 
have  noticed  with  mournful  interest  how  trivially  men 
seom  to  be  inihienced  by  what  they  call  their_religion,  and 
h ojwil| -pot c n 1 1  y  by  that  "  nature  which  it  is  the  alleged 
province  of  religion  to  eradicate  or  subdue.  From  fair  and 
manly  argument,  from  the  tenderest  and  holiest  sympathy 
on  the  part  of  those  who  desire  my  eternal  good,  I  pass  by 
many  gradations,  through  deliberate  unfairness,  to  a  spirit 
of  bitterness,  which  desires  with  a  fervor  inexpressible  in 
words  my  eternal  ill.  K"owT  were  religion  the  potent 
factor,  we  might  expect  a  homogeneous  utterance  from 
thosa.-pxofessing  a  common  creed,  while,  if  human  nature 
be  the  really  potent  factor,  we  may  expect  utterances  as 
heterogeneous  as  the  characters  of  men.  As  a  matter  of 
fact  we  have  the  latter;  suggesting  to  rny  mind  that  the 
common  religion,  professed  and  defended  by  these  dif- 
ferent people,  is  merely  ^the  accidental  conduit  through 
which  they  pour  their  own  tempers,  lofty  or  low,  courteous 
or  vulgar,  mild  or  ferocious,  as  the  case  may  be.  Pure  abuse, 
good  end,  I  have,  wherever  possible, 


deliberately  avoided  reading,  wishing,  indeed,  to  keep 
not  only  hatred,  malice,  and  uncharitableness,  but  even 
every  trace  of  irritation,  far  away  from  my  side  of  a  dis- 
cussion which  demands  not  only  good-temper,  but  large- 
ness, clearness,  and  many-sidedness  of  mind,  if  it  is  to 
guide  us  to  even  provisional  solutions. 

It  has  been  stated,  with   many  variations  of   note  and 
comment,  that  in  the  address  as  subsequently  published  by 
Messrs.    Longmans  I  have    retracted    opinions   uttered    at 
Belfast.     A   Roman    Catholic    writer   is   specially  strong 
upon  this  point.     Startled  by  the  deep  chorus  of  dissent 
which   my   "dazzling  fallacies"  have  evoked,  I  am   now 
trying  to  retreat.     This  he  will  by  no  means  tolerate.     "It    ^  >£ 
is  too  late  now  to  seek  to  hide  from  the  eyes  of  mankind    -"! 
one  foul  blot,  one  ghastly   deformity.     Professor  Tyndall    ., 
has  himself  told  us  how  and  where  this  address  of  his  was    "; 
composed.     It   was   written   among  the    glaciers  and    the 
solitudes  of  the  Swiss  mountains.     It  was  no  hasty,  hurried, 

Lj^**f. 


496  FRAGMENTS  OF  SCIENCE. 

crude  production;  its  every  sentence  bore  marks  of  thought 
and  care." 

My  critic  intends  to  be  severe:  he  is  simply  just.  In 
the  "solitudes"  to  which  he  refers  I  worked  with  deliber- 
ation, endeavoring  even  to  purify  my  intellect  by  disciplines 
similar  to  those  enjoined  by  his  own  church  for  the 
sauctification  of  the  soul.  I  tried,  moreover,  in  my  pon- 
deriugs  to  realize  not  only  tile  lawful,  but  the  expedient; 
and  to  permit  no  fear  to  act  upon  my  mind,  save  that  of 
uttering  a  single  word  on  which  I  could  not  take  my 
stand,  either  in  this  or  in  any  other  world. 

Still  my  time  was  so  brief,  the  difficulties  arising  from 
my  isolated  position  were  so  numerous,  and  my  thought 
and  expression  so  slow,  that,  in  a  literary  point  of  view,  I 
halted,  not  only  behind  the  ideal,  but  behind  the  possible. 
Hence,  after  the  delivery  of  the  address,  I  went  over  it 
with  the  desire,  not  to  revoke  its  principles,  but  to  improve 
it  verbally,  and  above  all  to  remove  any  word  which  might 
give  color  to  the  notion  of  "crudeness,  hurry,  or 
haste." 

In  connection  with  the  charge  of  atheism  my  critic 
refers  to  the  preface  to  the  second  issue  of  the  Belfast 
Address:  "  Christian  men,"  I  there  say,  "are  proved  by 
their  writings  to  have  their  hours  of  weakness  and  of  doubt, 
as  well  .as  their  hours  of  strength  and  of  convictionj_and 
men  like  myself  share,  in  their  own  way,  these  variations 
of  mood  and  tense.  Were  the  religious  moods  of  many  of 
my  assailants  the  only  alternative  ones,  I  do  not  know 
how  strong  the  claims  of  the  doctrine  of  "  Material 
Atheism  "  upon  my  allegiance  might  be.  Probably  they 
would  be  very  strong.  But,  as  it  is,  I  have  noticed  dur- 
ing_years  of  self-observation  that  it  is  not  in  hours  of  clear- 
ness and  vigor  that  this  doctrine  commends  itself  to  my 
mind;  that  in  the  presence  of  stronger  and  healthier 
thought  it  ever  dissolves  and  disappears,  as  offering  no 
solution  of  the  mystery  in  which  we  dwell,  and  of  which 
we  form  a  part." 

With  reference  to  this  honest  and  reasonable  utterance 
my  censor  exclaims,  "  This  is  a  most  remarkable  passage. 
Much  as  we  dislike  seasoning  polemics  with  strong  words, 
we  assert  that  this  Apology  only  tends  to  affix  with  links 
of  steel  to  the  name  of  Professor  Tyndall,  the  dread  im- 
putation against  which  he  struggles." 


L/Ti 


APOLOGY  FOR  THE  BELFAST  ADDRESS.         49? 

Here  we  have  a  very  fair  example  of  subjective  religious 
vigor.  But  my  quarrel  with  such  exhibitions  is  that  they 
do  not  always  represent  objective  fact.  JsTo  atheistic 
reasoning  can,  1  hold,  dislodge  religion  from  the  human 
heart.  Logic  cannot  deprive  us  of  life,  and  religion  is 
life  to  the  religious.  As  an  experience  of  consciousness  it 
is  beyond  the  assaults  of  logic.  But  the  religious  life  is 
often  projected  in  external  forms — I  use  the  word  in  its 
widest  sense — and  this  embodiment  of  the  religious  senti- 
ment will  have  to  bear  more  and  more,  as  the  world  becomes 
more  enlightened,  the  stress  of  scientific  tests.  We  must 
be  careful  of  projecting  into  external  nature  that  which 
belongs  to  ourselves.  My  critic  commits  this  mistake:  he 
feels,  and  takes  delight  in  feeling,  that  I  am  struggling, 
and  he  obviously  experiences  the  most  exquisite  pleasures 
of  "  the  muscular  sense  "  in  holding  me  down.  His  feel- 
ings are  as  real  as  if  his  imagination  of  what  mine  are 
were  equally  real.  His  picture  of  my  "  struggles"  is, 
however,  a  mere  delusion.  I  do  not  struggle.  I  do  not 
fear  the  charge  of  atheism;  nor  should  I  even  disavow  it, 
in  reference  to  aiiy  definition  of  the  Supreme  which  he,  or 
his  order,  would  be  likely  to  frame.  His  "links"  and  his 
"  steel  "  and  his  "dread  imputations"  are,  therefore,  even 
more  unsubstantial  than  my  "streaks  of  morning  cloud," 
and  they  may  be  permitted  to  vanish  together. 

These  minor  and  more  purely  personal  matters  at  an 
end,  the  weightier  allegation  remains~~that  at  Belfast  I 
misused  my  position  by  quitting  the  domain  of  science,  and 
riTaTsing  an  unjustifiable  raid  into  the  domain  of  theology. 
This  I  fail  to  see.  Laying  aside  abuse,  I  hope  my  accusers 
will  consent  to  reason  with  me.  •  Js  it  not  lawful  for  a 
scientific  man  to  speculate  on  the  antecedents  of  the  solar 
system?  Did  Kant,  Laplace  and  William  Herschel  quit  their 
legitimate  spheres,  when  they  prolonged  the  intellectual 
mum  beyond  the  boundary  of  experience,  and  propounded 
the  nebular  theory?  Accepting  that  theory  as  probable,  is 
it  not  permitted  to  a'scientific  man  to  follow  up,  in  idea, 
tlie.  sejjes  of  changes  associated  with  the  condensation  of 
the  nebulae;  to  picture  the  successive  detachment  of  planets 
and  moons,  a.nd  the  relation  of  all  of  them  to  the  sun? 
If  I  look  upon  our  earth,  with  its  orbital  revolution  and 
axial  rotation,  as  one  small  issue  of  the  process  which  made 


498  FRAGMENTS  OF  SCIENCE. 

the  solar  system  what  it  is,  will  any  theologian  deny  my 
right  to  entertain  and  express  this  theoretic  view?  Time 
was  when  a  multitude  of  theologians  would  have  been 
found  to  do  so — when  that  arch-enemy  of  science  which 
now  vaunts  its  tolerance  would  have  made  a  speedy  end  of 
the  man  who  might  venture  to  publish  any  opinion  of  the 
kind.  But,  that  time,  unless  the  world  is  caught  strangely 
slumbering,  is  forever  past. 

As  regards^  inorganic  nature,  then,  we  may  traverse, 
without  let  or  hindrance,  the  whole  distance  which  sepa- 
rates the  nebula?  from  the  worlds  of  to-day.  Hut  only  a  few 
years  ago  this  now  conceded  ground  of  science  was  theolog- 
ical ground.  I  could  by  no  means  regard  this  as  the  final 
and  sufficient  concession  of  theology;  and,  at  Belfast,  I 
thought  it,  not  only  my  right  but  my  duty  to  state  that,  as 
regards  the  organic  world,  we  must  enjoy  the  freedom 
which  we  have  already  won  in  regard  to  the  inorganic.  I 
could  not  discern  the  shred  of  a  title-deed  which  gave  any 
man,  or  any  class  of  men,  the  right  to  open  the  door  of 
one  of  these  worlds  to  the  scientific  searcher  and  to  close 
the  other  against  him.  And  I  considered  it  frankest, 
wisest,  and  in  the  long  run  most  conducive  to  permanent 
peace,  to  indicate,  without  evasion  or  reserve,  the  ground 
that  belongs  to  Science,  and  to  which  she  will  assuredly 
make  good  her  claim. 

I_have  been  reminded  that  an  eminent  predecessor  of 
mine  in  the  presidential  chair  expressed  a  totally  different 
view  of  the  cause  of  things  from  that  enunoiafed  by  me. 
In  doing  so  he  transgressed  the  bounds  of  science  at  least 
UuS  much  as  I  did;  but  nobody  raised  an  outcry  against 
him.  The  freedom  he  took  I  claim.  And  looking  at  what 
I  must  regard  as  the  extravagances  of  the  religious  world; 
at  the  very  inadequate  and  foolish  notions  concerning  this 
universe  which  are  entertained  by  the  majority  of  our 
authorized  religious  teachers;  at  the  waste  of  energy  on 
the  part  of  good  men  over  things  unworthy,  if  I  may  say 
it  without  discourtesy,  of  the  attention  of  enlightened 
heathens;  the  fight  about  the  fripperies  01 'Ritualism,  and 
the  verbal  quibbles  of  tlie^Athanasian  Creed;  the  forcing 
on  the  public  view  of  Pon tigTry-^Tgri mages;  the  dating 
of  historic  epochs  from  the  definition  of  the  Immaculate 
Conception;  the  proclamation  of  the  Divine  Glories  of 
the  Sacred  Heart — standing  iu  the  midst  of  these 


APOLOGY  FOR  THE  BELFAST  ADDRESS.        499 

chimeras,  which  astound  all  thinking  men,  it  did  not 
appear  to  me  extravagant  to  claim  the  public  tolerance 
for  an  hour  and  a  half,  for  the  statement  of  more  reason- 
able views — views  more  in  accordance  with  the  verities 
which  science  has  brought  to  light,  and  which  many  weary 
souls  would,  I  thought,  welcome  with  gratification  and 
relief. 

But  to  come  to  closer  quarters.  The  expression  to 
which  the  most  violent  exception  has  been  taken  is  this: 
"  Abandoning ull  disguise,  the  confession  I  feel  bound  to 
make  before  you  is,  that  I  prolong  the  vision  backward 
across  the  boundary  of  the  experimental  evidence,  and 
discern  in  that  Matter  which  we,  in  our  ignorance,  and 
notwithstanding  our  professed  reverence  for  its  Creator, 
have  hitherto  covered  with  opprobrium,  the  promise  and 
potency  of  every  form  and  quality  of  life."  To  call  it  a 
"chorus  of  dissent,"  as  my  Catholic  critic  does,  is  a  mild 
way  of  describing  the  storm  of  opprobrium  with  which 
this  statement  has  been  assailed.  But  the  first  blast  of 
passion  being  past,  I  hope  I  may  again  ask  my  opponents 
to  consent  to  reason.  First  of  all,  I  am  blamed  for  cross- 
ing the  boundary  of  the  experimental  evidence.  This,  I  -> 
reply,  is  the  habitual  action  of  the  scientific  wind — at  least 
of^  that  portion  of  it  which  applies  itself  to  physical  inves- 
tigation. Our  theories  of  light,  heat,  magnetism,  and  " 
electricity,  all  imply  the  crossing  of  this  boundary.  My 
paper  on  the  "  Scientific  Use  of  the  Imagination,"  and  my 
"  Lectures  on  Light,"  illustrate  this  point  in  the  amplest 
manner;  and  in  the  article  entitled  "  Matter  and  Force" 
in  the  present  relume  I  have  sought,  incidentally,  to  make 
clear,  that  in  physics  the  experiential  incessantly  leads 
to  the  ultra-experiential;  that  out  of  experience  there 
always  grows  something  finer  than  mere  experience,  and 
that  in  their  different  powers  of  ideal  extension  consists, 
for  the  most  part,  the  difference  between  the  great  and  the 
mediocre  investigator.  The  kingdom  of  science,  then, 
cometh  not  by  observation  and  experiment  alone,  but  is 
completed  by  fixing  the  roots  of  observation  and  experiment 
iii  a  region  inaccessible  to  both,  and  in  dealing  with  which 
Ave  are  forced  to  fall  back  upon  the  picturing  power  of  the 
mind. 

Passing  the  boundary  of  experience,  therefore,  does  not, 
in  the  abstract,  constitute  a  sufficient  ground  for  censure. 


500  FRAGMENTS  OP  SCIENCE. 

There  must  have  been  something  in  my  particular  mode 
of  crossing  it  which  provoked  this  tremendous  "  chorus  of 
dissent." 

Let  us  calmly  reason  the  point  out.  I  hold  the  nebular 
theory  as  it  was  held  by  Kant,  Laplace,  and  William 
Herschel,  and  as  it  is  held  by  the  best  scientific  intellects 
of  to-day.  According  to  it,  our  sun  and  planets  were  once 
diffused  through  space  as  an  impalpable  haze,  out  of  which 
by  condensation,  came  the  solar  system.  What  caused  the 
haze  to  condense?  Loss  of  heat.  What  rounded  the  sun 
and  planets?  That  which  rounds  a  tear — molecular  force. 
For  aeons,  the  immensity  of  which  overwhelms  mail's  con- 
ceptions, the  earth  was  unfit  to  maintain  what  we  call  life. 
It  is  now  covered  with  visible  living  things.  They  are  not 
formed  of  matter  different  from  that  of  the  earth  around 
them.  They  are,  on  the  contrary,  bone  of  its  bone,  and 
flesh  of  its  flesh.  How  were  they  introduced?  Was  life 
implicated  in  the  nebula — as  part,  it  may  be,  of  a  vaster 
and  wholly  Unfathomable  Life;  or  is  it  the  work  of  a 
Being  standing  ouside  the  nebula,  who  fashioned  it,  and 
vitalized  it;  but  whose  own  origin  and  ways  are  equally 
past  finding  out?  As  far  as  the  eye  of  science  has  hitherto 
ranged  through  nature,  no  intrusion  of  purely  creative 
power  into  any  series  of  phenomena  has  ever  been  observed. 
The  assumption  of  such  a  power  to  account  for  special 
phenomena,  though  often  made,  has  always  proved  a 
failure.  It  is  opposed  to  the  very  spirit  of  science;  and  I 
therefore  assumed  the  responsibility  of  holding  up,  in  con- 
trast with  it,  that  method  of  nature  which  it  has  been  the 
vocation  and  triumph  of  science  to  disclose,  and  in  the  ap- 
plication of  which  we  can  alone  hope  for  further  light. 
Holding,  then,  that  the  nebulas  and  the  solar  system,  life 
included,  stand  to  each  other  in  the  relation  of  the  germ  to 
the  finished  organism,  I  reaffirm  here,  not  arrogantly,  or 
defiantly,  but  without  a  shade  of  indistinctness,  the  posi- 
tion laid  down  at  Belfast. 

Not  with  the  vagueness  belonging  to  the  emotions,  but 
with  the  definiteness  belonging  to  the  understanding,  the 
scientific  man  has  to  put  to  himself  these  questions  regard- 
ing the  introduction  of  life  upon  the  earth.  He  will  be 
the  last  to  dogmatize  upon  the  subject,  for  he  knows  best 
that  certainty  is  here  for  the  present  unattainable.  His 
refusal  of  the  creative  hypothesis  is  less  an  assertion  of 


APOLOGY  FOR  THE  BELFAST  ADDRESS.         501 

knowledge  than  a  protest  against  the  assumption  of  knowl- 
edge which  must  long,  if  not  forever,  lie  beyond  us,  and 
the  claim  to  which  is  the  source  of  perpetual  confusion 
upon  earth.  With  a  mind  open  to  conviction  he  asks  his 
opponents  to  show  him  an  authority  for  the  belief  they  so 
strenuously  and  so  fiercely  uphold.  They  can  do  no  more 
than  point  to  the  book  of  Genesis,  or  some  other  portion 
of  the  Bible.  Profoundly  interesting,  and  indeed  pathetic, 
to  me  are  those  attempts  of  the  opening  mind  of  man  to 
appease  its  hunger  for  a  cause.  But  the  book  of  Genesis 
has  no  voice  in  scientific  questions.  To  the  grasp  of 
geology,  which  it  resisted  for  a  time,  it  at  length  yielded 
like.. potter's  clay;  its  authority  as  a  system  of  cosmogony 
being  discredited  on  all  hands,  by  the  abandonment  of 
the  obvious  meaning  of  its  writer.  It  is  a  poem,  not  a 
scientific  treatise.  In  the  former  aspect  it  is  forever 
beautiful:  in  the  latter  aspect  it  has  been,  and  it  will  con- 
tinue to  be,  purely  obstructive  and  hurtful.  To  knoivledge 
its  value  has  been  negative,  leading,  in  rougher  ages  than 
ours,  to  physical,  and  even  in  our  own  "free"  age  to 
moral  violence. 

No  incident  connected  with  the  proceedings  at  Belfast 
is  more  instructive  than  the  deportment  of  the  Catholic 
hierarchy  of  Ireland;  a  body  usually  too  wise  to  confer 
notoriety  upon  an  adversary  by  imprudently  denouncing 
him.  The  Times,  to  which  I  owe  a  great  deal  on  the 
score  of  fair  play,  where  so  much  has  been  unfair,  thinks 
that  the  Irish  cardinal,  archbishops,  and  bishops,  in  a 
recent  manifesto,  adroitly  employed  a  weapon  which  I, 
at  an  unlucky  moment,  placed  in  their  hands.  The  ante- 
cedents of  their  action  cause  me  to  regard  it  in  a  different 
light;  and  a  brief  reference  to  these  antecedents  will, 
I  think,  illuminate  not  only  their  proceedings  regarding 
Belfast,  but  other  doings  which  have  been  recently  noised 
abroad. 

Before  me  lies  a  document  bearing  the  date  of  Novem- 
ber. 1873,  which,  after  appearing  for  a  moment,  unac- 
countably vanished  from  public  view.  It  is  a  Memorial 
addressed,  by  seventy  of  the  students  and  ex-students  of 
the  Catholic  University  in  Ireland,  to  the  Episcopal  Board 
of  the  University;  and  it  constitutes  the  plainest  and 
bravest  remonstrance  ever  addressed  by  Irish  laymen  to 


502  FRAGMENTS  OF  SCIENCE. 

their  spiritual  pastors  and  masters.  It  expresses  the  pro- 
foundest  dissatisfaction  with  the  curriculum  marked  out 
for  the  students  of  the  University;  setting  forth  the  extra- 
ordinary fact  that  the  lecture-list  for  the  faculty  of  science, 
published  a  month  before  they  wrote,  did  not  contain  the 
name  of  a  single  professor  of  the  physical  or  natural 
sciences. 

The  memorialists  forcibly  deprecate  this,  and  dwell 
upon  the  necessity  of  education  in  science:  "The  distin- 
guishing mark  of  this  age  is  its  ardor  for  science.  The 
natural  sciences  have,  within  the  last  fifty  years,  become 
the  chiefest  study  in  the  world;  they  are  in  our  time  pur- 
sued with  an  activity  unparalleled  in  the  history  of  man- 
kind. Scarce  a  year  now  passes  without  some  discovery 
being  made  in  these  sciences  which,  as  with  the  touch  of 
the  magician's  wand,  shivers  to  atoms  theories  formerly 
deemed  unassailable.  It  is  through  the  physical  and  natural 
sciences  that  the  fiercest  assaults  are  now  made  on  our 
religion.  Xo  more  deadly  weapon  is  used  against  our  faith 
than  the  facts  incontestably  provecf  by  modern  researches 
in  science.'" 

Such  statements  must  be  the  reverse  of  comfortable  to  a 
number  of  gentlemen  who,  trained  in  the  philosophy  of 
Thomas  Aquinas,  have  been  accustomed  to  the  unquestion- 
ing submfsslon"  of  all  other  sciences  to  their  divine  science 
of  theology.  But  this  is  not  all:  "  One  thing  seems  cer- 
tain," say  the  memorialists,  viz.,  "that  if  chairs  for  the 
physical  and  natural  sciences  be  not  soon  founded  in  the 
Catholic  University,  very  many  young  men  will  have  their 
faith  exposed  to  dangers  which  the  creation  of  a  school  of 
science  in  the  University  would  defend  them  from.  For 
our  generation  of  Irish  Catholics  are  writhing  under  the 
sense  of  their  inferiority  in  science,  and  are  determined 
that  such  inferiority  shall  not  long  continue;  ami  so,  if 
scientific  training  be  unattainable  at  our  University,  they 
will  seek  it  at  Trinity  or  at  the  Queen's  Colleges,  in  not 
one  of  which  is  there  a  Catholic  professor  of  science." 

Those  who  imagined  the  Catholic  University  of 
Kensington  to  be  due  to  the  spontaneous  recognition,  on 
the  part  of  the  Roman  hierarchy,  of  the  intellectual  needs 
of  the  age,  will  derive  enlightenment  from  this,  and  still 
more  from  what  follows:  for  the  most  formidable  threat 
remains.  To  the  picture  of  Catholic  students  seceding 


APOLOGY  FOR  THE  BELFAST  ADDRESS.         503 

to  Trinity  and  the  Queen's  Colleges,  the  memorialists  add 
this  darkest  stroke  of  all:  'fl They  will,  in  the  solitude  of 
their  own  homes,  unaided  b'y  any  guiding  advice,  devour 
the  works. ..of  Ilueckel,  Darwin,  Jluxley,  Tyndall,  and 
Lyell;  works  innocuous  if  studied  under  a  professor  who 
would  point  out  the  difference  between  established  facts 
and  erroneous  inferences,  but  which  are  calculated  to  sap 
the  faith  of  a  solitary  student,  deprived  of  a  discriminating 
judgment  to  which  he  could  refer  for  a  solution  of  his 
difficulties." 

In  the  light  of  the  knowledge  given  by  this  courageous 
memorial,  and  of  similar  knowledge  otherwise  derived,  the 
recent  Catholic  manifesto  did  not  at  all  strike  me  as  a 
chuckle  over  the  mistake  of  a  maladroit  adversary,  but 
KiiUier  as  an  evidence  of  profound  uneasiness  on  the  part  of 
the  cardinal;  the  archbishops,  and  the  bishops  who  signed 
it.  lilies  u^ted  toward  the  Student's  Memorial,  however, 
with  their  accustomed  practical  wisdom.  As  one  conces- 
sion to  the  spirit  which  it  embodied,  the  Catholic  Univer- 
sity at  Kensington  was  brought  forth,  apparently  as  the 
effect  of  spontaneous  inward  force,  and  not  of  outward 
pressure  becoming  too  formidable  to  be  successfully 
opposed. 

The  memorialists  poii^t  with  bitterness  to  the  fact,  that 
"the  name  of  no  Irish  Catholic  is  known  in  connection  with 
tUephysical  and  natural  sciences."  But  this,  they  ought 
tojtnpvy,  is  the  complaint  of  free  and  cultivated  minds 
wherever  a  priesthood  exercises  dominant  power.  Pre- 
ciselv  the  same  complaint  has  been  made  with  respect  to 
the  Catholics  of  Germany.  The  great  national  literature 
and  the  scientific  achievements  of  that  country,  in  modern 
times,  are  almost  wholly  the  work  of  Protestants.  A  van- 
ishingly  small  fraction  of  it  only  is  derived  from  members 
of  the  Roman  Church,  although  the  number  of  these  in 
Germany  is  at  least  as  great  as  that  of  the  Protestants. 
"  The  question  arises,"  says  a  writer  in  an  able  German 
periodical,  "  what  is  the  cause  of  a  phenomenon  so  humil- 
iating to  the  Catholics?  It  cannot  be  referred  to  want  of 
natural  endowment  due  to  climate  (for  the  Protestants  of 
southern  Germany  have  contributed  powerfully  to  the 
creations  of  the  German  intellect),  but  purely  to  outward 
circumstances.  And  these  are  readily  discovered  in  the 
pressure  exercised  for  centuries  by  the  Jesuitical  system, 


504  FRAGMENTS  OF  SCIENCE. 

which  has  crushed  out  of  Catholics  every  tendency  to  free 
mental  productiveness."  It  is,  indeed,  in  Catholic  coun- 
tries that  the  weight  of  Ultramontanism  has  been  most 
severely  felt.  It  is  in  such  countries  that  the  very  finest 
spirits,  who  have  dared,  without  quitting  their  faith,  to 
plead  for  freedom  or  reform,  have  suffered  extinction. 
The  extinction,  however,  was  more  apparent  than  real,  and 
Herrnes,  Hirscher,  and  Giinther,  though  individually 
broken  and  subdued,  prepared  the  way,  in  Bavaria,  for 
the  persecuted  but  unflinching  Frohschammer,  for  D61- 
linger,  and  for  the  remarkable  liberal  movement  of  which 
Dollinger  is  the  head  and  guide. 

Though  molded  for  centuries  to  an  obedience  un- 
paralleled in  any  other  country,  except  Spain,  the  Irish 
intellect  is  beginning  to  show  signs  of  independence; 
demanding  a  diet  more  suited  to  its  years  than  the  pabu- 
lum of  the  middle  ages,  i  As  for  the  recent  manifesto  in 
which  pope,  cardinal,  archbishops,  and  bishops  are  united 
in  one  grand  anathema,  its  character  and  fate  are  shadowed 
forth  by  the  vision  of  Nebuchadnezzar  recorded  in  the 
book  of  Daniel1,'  It  resembles  the  image,  whose  form  was 
terrible,  but  the  gold,  and  silver,  and  brass,  and  iron  of 
which  rested  upon  feet  of  clay.  And  a  stone  smote  the 
feet  of  clay,  and  the  iron,  and  the  brass,  and  the  silver, 
and  the  gold,  were  broken  in  pieces  together,  and  became 
like  the  chaff  of  the  summer  threshing-floors,  and  the  wind 
carried  them  away. 

Monsignor  Capel  has  recently  been  good  enough  to  pro- 
claim af  once  the  friendliness  of  his  church  toward  true 
»  science,  and  her  right  to  determine  what  true  science  is. 
Let  us  dwell  for  a  moment  on  the  proofs  of  her  scientific 
competence.  AVhen  Halley's  comet  appeared  in  1456  it 
was  regarded  as  the  harbinger  of  God's  vengeance,  the 
dispenser  of  war,  pestilence,  and  famine,  and  by  order  of 
the  pope  the  church  bells  of  Europe  were  rung  to  scare 
the  monster  away.  An  additional  daily  prayer  was  added 
to  the  supplications  of  the  faithful.  The  comet  in  due 
time  disappeared,  and  the  faithful  were  comforted  by  the 
assurance  that,  as  in  previous  instances  relating  to  eclipses, 
droughts,  and  rains,  so  also  as  regards  this  "nefarious" 
comet,  victory  had  been  vouchsafed  to  the  church. 

Both  Pythagoras  and  Copernicus  had  taught  the 
heliocentric  doctrine— .that  the  earth  revolves  round  the 


APOLOGY  FOR  THE  BELFAST  ADDRESS.         505 

sun.  In  the  exercise  of  her  right  to  determine  what  true 
science  is,  the  Church,  in  the  pontificate  of  Paul  V., 
stepped  in,  and  by  the  mouth  of  the  holy  Congregation  of 
the  Index,  delivered,  on  March  5,  1616,  the  following 
decree: 

And  whereas  it  hath  also  come  to  the  knowledge  of  the 
said  holy  congregation  that  the  false  Pythagorean  doctrine 
of  the  mobility  of  the  earth  and  the  immobility  of  the  sun, 
entirely  opposed  to  Holy  writ,  which  is  taught  by  Nicolas 
Copernicus,  is  now  published  abroad  and  received  by  many. 
In  order  that  this  opinion  may  not  further  spread,  to  the 
tlitmage  of  Catholic  truth,  it  is  ordered  that  this  and  all 
other  books  teaching  the  like  doctrine  be  suspended,  and  by 
t'hift  decree  they  are  all  respectively  suspended,  forbidden, 
and  condemned. 

But  why  go  back  to  1456  and  1616?  Far  be  it  from  me 
to  charge  bygone  sins  upon  Monsignor  Capel,  were  it  not 
for  the  practices  he  upholds  to-day.  The  most  applauded 
dogmatist  and  champion  of  the  Jesuits  is,  I  am  informed, 
Perrone.  No  less  than  thirty  editions  of  a  work  of  his  have 
been  scattered  abroad  for  the  healing  of  the  nations.  His 
notions  of  physical  astronomy  are  virtually  those  of  1456. 
He  teaches, boldly  that  "  God  does  not  rule  by  universal 
law  .  .  .  that  when  God  orders  a  given  planet  to  stand 
still  He  does  not  detract  from  any  law  passed  by  Himself, 
but  orders  that  planet  to  move  round  the  sun  for  such  and 
such  a  time,  then  to  stand  still,  and  then  again  to  move, 
as  His  pleasure  may  be."  Jesuitism  proscribed  Froh- 
schamrner  for  questioning  its  favorite  dogma,!' that  every 
human  soul  was  created  by  a  direct  supernatural  act  of 
God,  and  for  asserting  that  man,  body  and  soul,  came  from 
his  parents.  This  is  the  system  that  now  strives  for 
universal  power;  it  is  from  it,  as  Monsignor  Capel 
graciously  informs  us,  that  we  are  to  learn  what  is  allow- 
able in  science,  and  what  is  not! 

In  the  face  of  such  facts,  which  might  be  multiplied  at 
will,  it  requires  extraordinary  bravery  of  mind,  or  a 
reliance  upon  public  ignorance  almost  as  extraordinary,  to 
make  the  claims  made  by  Monsiguor  Capel  for  his  Church. 

Before  me  is  a  very  remarkable  letter  addressed  in  1875 
by  the  bishop  of  Montpellier  to  the  deans  and  professors 
of  faculties  of  Montpellier,  in  which  the  writer  very 
clearly  lays  down  the  claims  of  his  Church.  He  had  been 


506  FRA  OMENTS  0  F  SCIENCE. 

startled  by  an  incident  occurring  in  a  course  of  lectures  on 
physiology  given  by  a  professor,  of  whose  scientific  capacity 
there  was  no  doubt,  but  who,  it  was  alleged,  rightly  or 
wrongly,  had  made  his  course  the  vehicle  of  materialism. 
"  Je  ne  me  suis  point  donne,"  says  the  bishop,  '"  la  mission 
que  je  remplis  au  milieu  de  vous.  '  Personne,  au  te- 
moignage  de  saint  Paul,  ne  s'attribtie  a  soi-rnerne  un  pareil 
houneur;  il  y  faut  etre  appele  de  Dieu,  comme  Aaron/ 
Et  pourquoi  en  est-il  ainsi?  C'est  parce  que,  selon  le 
metne  Apotre,  nous  devons  etre  les  ambassadeurs  de  Dieu; 
et  il  n'est  pas  dans  les  usages,  pas  plus  qn'il  n'est  dans  la 
raison  et  le  droit,  qu'un  envoye  s'accredite  lui-meme. 
Mais,  si  j'ai  regu  d  En-Haut  une  mission;  si  PEglise,  au 
notn  de  Dieu  lui-meme,  a  souscrit  mes  lettres  de  creance, 
me  sieraitil  de  manquer  aux  instructions  qu'elle  nr'a 
donn6es  et  d'entendre,  en  un  sens  different  du  sien,  le  role 
qu'elle  in 'a  confie? 

"  Or,  Messieurs,  la  sainte  Eglise  se  croit  investie  du 
droit  absolu  d'enseigner  les  hommes;  elle  se  croit  deposi- 
taire  de  la  verite,  n on  pas  de  la  verite  fragmentaire,  incom- 
plete, me*  lee  de  certitude  et  d'hesitation,  mais  de  la  verite 
totale,  complete,  au  point  de  vue  religieux.  Bien  plus, 
elle  est  si  sure  de  1'infaillibilite  que  son  Fondateur  diviu 
lui  a  comrnuniquee,  comrne  la  dot  magnifique  de  leur  in- 
dissoluble alliance,  que,  meme  dans  Ford  re  uaturel,  scien- 
tifique  ou  philosophique,  moral  ou  politique,  elle  n'admet 
pas  qu'un  systeme  puisse  etre  soutenu  et  adopte  par  des 
Chretiens,  s'il  contredita  des  dogmes  definis.  Elle  consid- 
ere  que  la  negation  voloutaire  et  opiniatre  d'un  seul  point 
de  sa  doctrine  rend  coupable  du  peche  d'heresie;  et  elle 
pense  que  toute  heresie  formelle,  si  on  ne  la  rejette  pas 
courageusement  avant  de  paraitre  devant  Dieu,  entraine 
avec  soi  la  perte  certaine  de  la  grace  et  de  1'eternite." 

The  bishop  recalls  those  whom  he  addresses  from  the 
false  philosophy  of  the  present  to  the  philosophy  of  the 

rt,  and  foresees  the  triumph  of  the  latter.  "  Avant  que 
dix-neuvieme  siecle  s'acheve,  la  vieille  philosophic 
scolastique  aura  repris  sa  place  dans  la  juste  admiration 
du  monde.  II  lui  faudra  pourtant  bien  du  temps  pour 
guerir  les  maux  de  tout  genre,  causes  par  son  indigne 
rivale;  et  pendant  de  longues  annees  encore,  ce  nom  de 
philosophic,  le  plus  grand  de  la  langue  humaine  apres 
celui  de  religion,  sera  suspect  aux  anies  qui  sesouviendront 


APOLOGY  FOR  THE  BELFAST  ADDRESS.         507 

de  la  science  impie  et  materialists  de  Locke,  de  Condillacou 
d'Helvetius.  L  heure  actuelle  est  aux  sciences  naturelles: 
c'est  maintenaut  Piristrnment  de  combat  centre  1'Eglise 
et  contre  toute  foi  religieuse.  Nous  ne  les  redoutons  pas." 
Further  on  the  bishop  warns  his  readers  that  everything 
can  be  abused.  Poetry  is  good,  but  in  excess  it  may  injure 
practical  conduct.  "  Les  mathematiques  sont  excellentes: 
et  Bossuet  les  a  louees  *  comme  etant  ce  qui  sert  le  plus  a 
la  justesse  du  raisonnement;'  mais  si  on  s'accoutume  ex- 
clusivernent  a  leur  methode,  rien  de  ce  qui  appartient  a 
1'ordre  moral  ne  parait  plus  pouvoir  etre  demontre;  et 
Fenelon  a  pu  parler  de  I'ensorceUcment  et  des  attraits 
diaboliqnes  de  la  geometric." 

The  learned  bishop  thus  finally  accentuates  the  claims 
of  the  Church:  "  Cornme  le  definissait  le  Pape  Leon  X., 
au  cinquieme  concile  cecumenique  de  Latran,  '  Le  vrai  ne 
pent  pas  etre  contraire  a  lui-m£me:  par  consequent,  toute 
assertion  contraire  a  une  verite  de  foi  revelee  est  neces- 
sairement  et  absolument  fausse.'  II  suit  de  la  que,  sans 
entrer  dans  1'examen  scientifique  de  telle  ou  telle  question 
de  physiologie,  inais  par  la  seule  certitude  de  nos  dogmes, 
nous  pouvons  juger  du  sort  de  telle  ou  telle  hypothese,  qui 
est  une  machine  de  guerre  anti-chretienne  plutot  qu'une 
conquete  serieuse  sur  les  secrets  et  les  mysteres  de  la 
nature.  .  .  .  C'est  un  dogme  que  1'homme  a  ete  forme 
et  fa9onne  des  mains  de  Dieu.  Done  il  est  faux, 
heretique,  contraire  a  la  dignite  du  Createur  et  offensant 
pour  son  chef -d 'can vre,  de  dire  que  1'homme  constitue 
la  septieme  espece  des  singes.  .  .  .  Heresie  encore 
de  dire  que  le  genre  humain  n'est  pas  sorti  d'un  seul 
couple,  et  qu'ou  y  peut  compter  jusqu'a  douze  races 
distinctes!" 

The  course  of  life  upon  earth,  as  far  as  science  can  see, 
has  been  one  of  amelioration— a  steady  advance  on  the 
AKJiQle  from  the  lower  to  the  higher.  The  continued  effort 
of  animated  nature  is  to  improve  its  condition  and  raise 
itself  to  a  loftier  level.  In  man  improvement  and  amelior- 
ation depend  largely  upon  the  growth  of  conscious  knowl- 
edge, by  which  the  errors  of  ignorance  are  continually 
molded,  and  truth  is  organized.  It  is  the  advance  of 
knowledge  that  has  given  a  "materialistic  color  to  the  phi- 
losophy of  this  age.  Materialism  is  therefore  not  a  thing  to 


508  FRAGMENTS  OF  SCIENCE. 

be  monrned  over,  but  to  be  honestly  considered — accepted 
if  it  be  wholly  true,  rejected  if  it  be  wholly  false,  wisely 
sifted  and  turned  to  account  if  it  embrace  a  mixture  of 
truth  and  error.  Of  late  years  the  study  of  the  nervous 
system,  and  its  relation  to  thought  and  feeling,  have 
profoundly  occupied  inquiring  minds.  It  is  our  duty 
not  to  shirk — it  ought  rather  to  be  our  privilege  to  accept 
— the  established  results  of  such  inquiries,  for  here 
assuredly  our  ultimate  weal  depends  upon  our  loyalty  to 
the  truth.  Instructed  as  to  the  control  which  the  nervous 
system  exercises  over  man's  moral  and  intellectual  nature, 
we  shall  be  better  prepared,  not  only  to  mend  their  mani- 
fold defects,  but  also  to  strengthen  and  purify  both.  Is 
mind  degraded  by  this  recognition  of  its  dependence? 
Assuredly  not.  Matter,  on  the  contrary,  is  raised  to  the 
level  it  ought  to  occupy,  and  from  which  timid  ignorance 
would  remove  it. 

But  the  light  is  dawning,  and  it  will  become  stronger  as 
time  goes  on.  Even  the  Brighton  "Church  Congress" 
affords  evidence  of  this.  From  the  manifold  confusions 
of  that  assemblage  my  memory  has  rescued  two  items, 
which  it  would  fain  preserve:! jthe  recognition  of  a  relation 
between  health  and  religion,  and  the  address  of  the  Eev. 
Harry  Jones.  Out  of  the  conflict  of  vanities  his  words 
emerge  wholesome  and  strong,  because  undrugged  by 
dogma,  coming  directly  from  the  warm  brain  of  one  who 
knows  what  practical  truth  means,  and  who  has  faith  in 
its  vitality  and  inherent  power  of  propagation.  I  wonder 
whether  he  is  less  effectual  in  his  ministry  than  his  more 
embroidered  colleagues?  It  surely  behooves  our  teachers  to 
come  to  some  definite  understanding  as  to  this  question  of 
health;  to  see  how,  by  inattention  to  it,  we  are  defrauded, 
negatively  and  positively:  negatively,  by  the  privation  of 
that  "sweetness  and  light"  which  is  the  natural  con- 
comitant of  good  health;  positively,  by  the  insertion  into 
life  of  cynicism,  ill-temper,  and  a  thousand  corroding 
anxieties  which  good  health  would  dissipate.  We  fear  and 
scorn  '•'  materialism."  But  he  who  knew  all  about  it,  and 
could  apply  his  knowledge,  might  become  the  preacher  of 
a  new  gospel.  Not,  however,  through  theecstatic  moments 
of  the  individual  does  such  knowledge  come,  but  through 
the  revelations  of  science,  in' connection  wiih  the  history 
of  mankind. 


APOLOGY  FOR  THE  BELFAST  ADDRESS.         509 

Why  should  jthe  Roman  Catholic  Church  call  gluttony  a 
mortal  sin?  Why  should  fasting  occupy  a  place  in  the 
disciplines  of  religion?  What  is  the  meaning  of  Luther's 
advice  to  the  young  clergyman  who  came  to  him,  perplexed 
with  the  difficulties  of  predestination  and  election,af  it  be 
not  that,  in  virtue  of  its  action  upon  the  brain,  when  wisely 
applied,  there  is  moral  and  religious  virtue  even  in  a  hydro- 
carbon? To  use  the  old  language,  food  and  drink  are 
creatures  of  God,  and  have  therefore  a  spiritual  value. 
Through  our  neglect  of  the  monitions  of  a  reasonable 
materialism  we  sin  and  suffer  daily.  I  might  here  point  to 
the  train  of  deadly  disorders  over  which  science  has  given 
modern  society  such  control — disclosing  the  lair  of  the 
material  enemy,  insuring  his  destruction,  and  thus  pre- 
venting that  moral  squalor  and  hopelessness  which  habit- 
ually tread  on  the  heels  of  epidemics  in  the  case  of  the 
poor. 

Rising  to  higher  spheres,  the  visions  of  Swedenborg,  and 
the  ecstasy  of  Plotinus  and  Porphyry,  are  phases  of  that 
psychical  condition,  obviously  connected  with  the  nervous 
system  and  state  of  health,  on  which  is  based  the  Vedic 
doctrine  of  the  absorption  of  the  individual  into  the 
universal  soul.  Plotinus  taught  the  devout  how  to  pass 
into  a  condition  of  ecstasy.  Porphyry  complains  of  having 
been  only  once  united  to  God  in  eighty-six  years,  while  his 
master  Plotinus  had  been  so  united  six  times  in  sixty 
years.*  A  friend  who  knew  Wordsworth  informs  me  that 
the  poet,  in  some  of  his  moods,  was  accustomed  to  seize 
hold  of  an  external  object  to  assure  himself  of  his  own 
bodily -existence.  As  states  of  consciousness  such  phenom- 
.ena  have  an  undisputed  reality,  and  a  substantial  identity; 
ibut  they  are  connected  with  the  most  heterogeneous 
objective  conceptions.  The  subjective  experiences  are 
similar,  because  of  the  similarity  of  the  underlying  organ- 
izations. 

But  for  those  who  wish  to  look  beyond  the  practical 
facts,  there  will  always  remain  ample  room  for  speculation. 
Take  the  argument  of  the  Lucretian  introduced  in  the 
Belfast  address.  As  far  as  I  am  aware,  not  one  of  my 

*  I  recommend  to  the  reader's  particular  attention  Dr.  Draper's 
important  work  entitled,  "  History  of  the  Conflict  between  Religion 
and  Science."  (Messrs.  H.  S.  King  and  Co.) 


510  FRAGMENTS  OF  SCIENCE. 

assailants  has  attempted  to  answer  it.  Some  of  them, 
indeed,  rejoice  over  the  ability  displayed  by  Bishop  Butler 
in  rolling  back  the  difficulty  on  his  opponent;  and  they 
even  imagine  that  it  is  the  bishop's  own  argument  that  is 
there  employed.  But  the  raising  of  a  new  difficulty  does 
not  abolish — does  not  even  lessen — -the  old  one,  and  the 
argument  of  the  Lucretian  remains  untouched  by  anything 
the  bishop  has  said  or  can  say. 

And  here  it  may  be  permitted  me  to  add  a  word  to  an  im- 
portant controversy  now  going  on:  and  which  turns  on  the 
question:  Do  states  of  consciousness  enter  as  links  into  the 
chain  of  antecedence  and  sequence,  which  give  rise  to 
bodily  actions,  and  to  other  states  of  consciousness;  or  are 
they  merely  by-products,  which  are  not  essential  to  the 
physical  processes  going  on  in  the  brain?  Speaking  for 
myself,  it  is  certain  that  I  have  no  power  of  imagining 
states  of  consciousness,  interposed  between  the  molecules 
of  the  brain,  and  influencing  the  transference  of  motion 
among  the  molecules.  The  thought  "  eludes  all  mental 
presentation;"  and  hence  the  logic  seems  of  iron  strength 
which  claims  for  the  brain  an  automatic  action,  unin- 
fluenced by  states  of  consciousness.  But  it  is,  I  believe, 
admitted  by  those  who  hold  the  automaton-theory,  that 
states  of  consciousness  are  produced  by  the  marshaling  of 
the  molecules  of  the  brain:  and  this  production  of  con- 
sciousness by  molecular  motion  is  to  me  quite  as  incon- 
ceivable on  mechanical  principles  as  the  production  of 
molecular  motion  by  consciousness.  If,  therefore,  I  reject 
one  result,  I  must  reject  both.  I,  however,  reject  neither, 
and  thus  stand  in  the  presence  of  two  Incomprehensihles, 
instead  of  one  Incomprehensible.  While  accepting  fear- 
lessly the  facts  of  materialism  dwelt  upon  in  these  pages,  I 
bow  my  head  in  the  dust  before  that  mystery  of  mind, 
which  has  hitherto  defied  its  own  penetrative  power,  and 
which  may  ultimately,  resolve  itself  into  a  demonstrable 
impossibility  of  self-penetration. 

But  the  secret  is  an  open  one — the  practical  monitions 
are  plain  enough,  which  declare  that  on  our  dealings  with 
matter  depend  our  weal  and  woe,  physical  and  moral. 
The  state  of  mind  which  rebels  against  the  recognition  of 
the  claims  of  "  materialism"  is  not  unknown  tome.  I 
can  remember  a  time  when  I  regarded  my  body  as  a  weed, 


THK  RE  V.  JAMKR  MARTINEA  V.  511 

so  much  more  highly  did  I  prize  the  conscious  strength  and 
pleasure  derived  from  moral  and  religious  feeling — which, 
I  may  add,  was  mine  without  the  intervention  of  dogma. 
The  error  was  not  au  ignoble  one,  but  this  did  not  save  it 
from  the  penalty  attached  to  error.  Saner  knowledge 
taught  me  that  the  body  is  no  weed,  and  that  treated  as 
such  it  would  infallibly  avenge  itself.  Am  1  personally 
lowered  by  this  change  of  front?  Not  so.  Give  me  their 
health,  and  there  is  no  spiritual  experience  of  those  earlier 
years — no  resolve  of  duty,  or  work  of  mercy,  no  work  of 
self-renouncement,  no  solemnity  of  thought,  no  joy  in  the 
life  and  aspects  of  nature — that  would  not  still  be  mine; 
and  this  without  the  least  reference  or  regard  to  any  purely 
personal  reward  or  punishment  looming  in  the  future. 

And  now  I  have  to  utter  a  "farewell"  free  from  bitter- 
ness to  all  my  readers;  thanking  my  friends  for  a  sympathy 
more  steadfast,  I  would  fain  believe,  if  less  noisy,  than  the 
antipathy  of  my  foes;  and  commending  to  these  a  passage 
from  Bishop  Butler,  which  they  have  either  not  read  or 
failed  to  lay  to  heart.  "  It  seems,"  saith  the  bishop, 
"that  men  would  be  strangely  headstrong  and  self-willed, 
and  disposed  to  exert  themselves  with  an  impetuosity 
which  would  render  society  insupportable,  and  the  living 
in  it  impracticable,  were  it  not  for  some  acquired  moder- 
ation and  self-government,  some  aptitude  and  readiness  in 
restraining  themselves,  and  concealing  their  sense  of 
things." 


CHAPTER  XXXIII. 

THE  REV.  JAMES  MARTINEATJ  AND  THE  BELFAST  ADDRESS.* 

PRIOR  to  the  publication  of  the  fifth  edition  of  these 
"Fragments"  my  attention  had  been  directed  by  several 
estimable,  and  indeed  eminent,  persons,  to  an  essay  by  the 
Rev.  James  Martineau,  as  demanding  serious  consideration 
at  my  hands.  I  tried  to  give  the  essay  the  attention 
claimed  for  it,  and  published  tny  views  of  it  as  an  Intro- 
duction to  Part  II.  of  the  "  Fragments."  I  there  referred, 
and  here  again  refer  with  pleasure,  to  the  accord  subsisting 
between  Mr.  Martineau  and  myself  on  certain  points  of 

*  "Fortnightly  Review." 


512  FRAGMENTS  OF  SCIENCE. 

biblical  Cosmogony.  "In  so  far,"  says  he,  "as  Church 
belief  is  still  committed  to  a  given  Cosmogony  and  natural 
history  of  man,  ii  lies  open  to  scientific  refutation."  And 
again:  "It  turns  out  that  with  the  sun  and  moon  and 
stars,  and  in  and  on  the  earth,  before  and  after  the  appear- 
ance of  our  race,  quite  other  things  have  happened  than 
those  which  the  sacred  Cosmogony  recites."  Once  more: 
"  The  whole  history  of  the  genesis  of  things  Eeligion  must 
surrender  to  the  Sciences."  Finally,  still  more  emphatically: 
"In  the  investigation  of  the  genetic  order  of  things, 
Theology  is  an  intruder,  and  must  stand  aside."  This 
expresses,  only  in  words  of  fuller  pith,  the  views  which  I 
ventured  to  enunciate  in  Belfast.  "The  impregnable 
position  of  science,"  I  there  say,  "  may  be  stated  in  a  few 
words.  We  claim,  and  we  shall  wrest  from  Theology,  the 
entire  domain  of  Cosmological  theory."  Thus  Theology, 
so  far  as  it  is  represented  by  Mr.  Martineau,  and  Science, 
so  far  as  I  understand  it,  are  in  absolute  harmony  here. 

But  Mr.  Martineau  would  have  just  reason  to  complain 
of  me,  if,  by  partial  citation,  I  left  my  readers  under  the 
impression  that  the  agreement  between  us  is  complete. 
At  the  opening  of  the  eighty-ninth  session  of  the  Man- 
chester New  College,  London,  on  October  6,  1874,  he,  its 
principal,  delivered  an  address  bearing  the  title  "  Eeligion 
as  affected  by  Modern  Materialism;"  the  references  and 
general  tone  of  which  make  evident  the  depth  of  its 
author's  discontent  with  my  previous  deliverance  at  Belfast. 
I  find  it  difficult  to  grapple  with  the  exact  grounds  of  this 
discontent.  Indeed,  logically  considered,  the  impression 
teft  upon  my  mind  by  an  essay  of  great  aesthetic  merit,  con- 
taining many  passages  of  exceeding  beauty,  and  manysenti- 
ments  which  none  but  the  pure  in  heart  could  utter  as 
they  are  uttered  here,  is  vague  and  unsatisfactory.  The 
author  appears  at  times  so  brave  and  liberal,  at  times  so 
timid  and  captious,  and  at  times,  if  I  dare  say  it,  so 
imperfectly  informed,  regarding  the  position  he  assails. 

At  the  outset  of  his  address  Mr.  Martineau  states  with 
some  distinctness  his  "sources  of  religions  faith."  They 
are  two — "the  scrutiny  of  Nature  "and  "the  interpreta- 
tion of  Sacred  Books."  It  would  have  been  a  theme 
worthy  of  his  intelligence  to  have  deduced  from  these  two 
sources  his  religion  as  it  stands.  (But  not  another  word  is 
said  about  the  "  Sacred  Books."  Having  swept  with  the 


THE  REV.  JAMES  MARTINEAU.  513 

besom  of  Science  various  "  books'"  contemptuously  away, 
he  does  not  define  the  Sacred  residue;  much  less  give  us 
the  reasons  why  he  deems  them  sacred.*  His  references 
to  "  Nature,"  on  the  other  hand,  are  magnificent  tirades 
against  Nature,  intended,  apparently,  to  show  the  wholly 
abominable  character  of  man's  antecedents  if  the  theory  of 
evolution  be  true.  Here  also  his  mood  lacks  steadiness. 
While  joyfully  accepting,  at  one  place,  "  the  widening 
space,  the  deepening  vistas  of  time,  the  detected  marvels 
of  physiological  structure,  and  the  rapid  filling-in  of  the 
missing  links  in  the  chain  of  organic  life,"  he  falls,  at 
another,  into  lamentation  and  mourning  over  the  very 
theory  which  renders  "organic  life"  "a  chain."  He 
claims  the  largest  liberality  for  his  sect,  and  avows  its  con- 
tempt for  the  dangers  of  possible  discovery.  But  imme- 
diately afterward  he  damages  the  claim,  and  ruins  all 
confidence  in  the  avowal.  He  professes  sympathy  with 
modern  Science,  and  almost  in  the  same  breath  he  treats, 
or  certainly  will  be  understood  to  treat,  the  Atomic  Theory, 
and  the  doctrine  of  the  Conservation  of  Energy,  as  if  they 
were  a  kind  of  scientific  thimble-riggery. 

His  ardor,  moreover,  renders  him  inaccurate;  causing 
him  to  see.discord  between  scientific  men  where  nothing 
but  harmony  reigns.  In  his  celebrated  address  to  the 
Congress  of  German  Naturforscher,  delivered  at  Leipzig, 
three  years  ago,  Du  Bois-Keymond  speaks  thus:  "  What 
co-nceivable  connection  subsists  between  definite  movements 
of  definite  atoms  in  my  brain,  on  the  one  hand,  and  on 
the  other  hand  such  primordial,  indefinable,  undeniable, 
facts  as  these:  I  feel  pain  or  pleasure;  I  experience  a 
sweet  taste,  or  smell  a  rose,  or  hear  an  organ,  or  see  some- 
thing red.  ...  It  is  absolutely  and  forever  inconceivable 
that  a  number  of  carbon,  hydrogen,  nitrogen,  and  oxygen 
atoms  should  be  otherwise  than  indifferent  as  to  their"own 
position  and  motion,  past,  present,  or  future.  It  is  utterly 
inconceivable  how  consciousness  should  result  from  their 
joint  action." 

This  language,  which  was  spoken  in  1872,  Mr.  Martineau 

*  Mr.  Martineau's  use  of  tlie  term  "  sacred  "  is  unintentionally  mis- 
leading. In  his  later  essays  we  are  taught  that  he  does  not  mean  to 
restrict  it  to  the  Bible.  He  does  not,  however,  mention  the  "  books  " 
beyond  those  of  the  Bible  to  which  he  would  apply  the  term. 
1879. 


514  FRAGMENTS  OF  SCIENCE. 

"  freely "  translates,  and  quotes  against  me.  The  act  is 
due  to  misapprehension.  Evidence  is  at  hand  to  prove 
that  I  employed  similar  language  twenty  years  ago.  It  is 
to  be  fonnd  in  the  Saturday  Review  for  1860;  bnt  a 
sufficient  illustration  of  the  agreement  between  my  friend 
Du  Bois-Reymond  and  myself  is  furnished  by  the  discourse 
on  "  Scientific  Materialism,"  delivered  in  1868,  then 
widely  circulated,  and  reprinted  here.  The  reader  who 
compares  the  two  discourses  will  see  that  the  same  line  of 
thought  is  pursued  in  both,  and  that  perfect  agreement 
reigns  between  my  friend  and  me.  In  the  very  address  he 
criticises,  Mr.  Martineau  might  have  seen  that  precisely 
the  same  position  is  maintained.  A  quotation  will  prove 
this:  "Thus  far/'  I  say,  "our  way  is  clear,  but  now 
cornes  my  difficulty.  Your  atoms  are  individually  without 
sensation,  much  more  are  they  without  intelligence.  May 
I  ask  you,  then,  to  try  your  hand  upon  this  problem? 
Take  your  dead  hydrogen  atoms,  your  dead  oxygen  atoms, 
your  dead  carbon  atoms,  your  dead  nitrogen  atoms,  your 
dead  phosphorus  atoms,  and  all  the  other  atoms,  dead  as 
grains  of  shot,  of  which  the  brain  is  formed.  Imagine 
them  separate  and  sensationless;  observe  them  running 
together  and  forming  all  imaginable  combinations.  This, 
as  a  purely  mechanical  process,  i&.£eeable  by  the  mind. 
But  can  you  see,  or  dream,  or  in  any  way  imagine,  how 
ort  of  that  mechanical  act,  and  from  these  individually 
dead  atoms,  sensation,  thought,  and  emotion  are  to  rise? 
Are  you  likely  to  extract  Homer  out  of  the  rattling  of  dice, 
or  the  Differential  Calculus  out  of  the  clash  of  billiard 
balls?  ...  I  can  follow  a  particle  of  musk  until  it  reaches 
the  olfactory  nerve;  I  can  follow  the  waves  of  sound  until 
their  tremors  reach  the  water  of  the  labyrinth,  and  set  the 
otoliths  and  Corti's  fibers  in  motion;  I  can  also  visualize 
the  waves  of  ether  as  they  cross  the  eye  and  hit  the  retina. 
Nay,  more,  I  am  able  to  pursue  to  the  central  organ  the 
motion  thus  imparted  at  the  periphery,  and  to  see  in  idea 
the  very  molecules  of  the  brain  thrown  into  tremors.  My 
insight  is  not  baffled  by  these  physical  processes.  What 
baffles  and  bewilders  me  is  the  notion  that  from  these  phys- 
ical tremors  things  so  utterly  incongruous  with  them  as 
sensation,  thought,  and  emotion  can  be  derived."  It  is 
only  a  complete  misapprehension  of  our  true  relationship 
that  could  induce  Mr.  Martineau  to  represent  Du  Bois- 
Keymond  and  myself  as  opposed  to  each  other. 


THE  REV.  JAMES  MARTINEAU.  515 

"  The  affluence  of  illustration,"  writes  an  able  and 
sympathetic  reviewer  of  this  essay,  in  the  New  York 
Tribune,  "in  which  Mr.  Martineau  delights  often  impairs 
the  distinctness  of  his  statements  by  diverting  the  atten- 
tion of  the  reader  from  the  essential  points  of  his  discussion 
to  the  beauty  of  his  imagery,  and  thus  disminishes  their 
power  of  conviction."  To  the  beauties  here  referred  to  I 
bear  willing  testimony;  but  the  reviewer  is  strictly  just  in 
his  estimate  of  their  effect  upon  my  critic's  logic.  The 
"affluence  of  illustration,"  and  the  heat,  and  haze,  and 
haste,  generated  by  its  reaction  upon  Mr.  Martineau's 
own  mind,  often  produce  vagueness  where  precision  is 
the  one  thing  needful — poetic  fervor  where  we  require 
judicial  calm;  and  practical  unfairness  where  the  strictest 
justice  ought  to  be,  and  I  willingly  believe  is  meant  to  be, 
observed. 

In  one  of  his  nobler  passages  Mr.  Martineau  tells  us 
how  the  pupils  of  his  college  have  been  educated  hither- 
to: "  They  have  been  trained  under  the  assumptions 
(1)  that  the  Universe  which  includes  us  and  folds  us 
round  is  the  life-dwelling  of  an  Eternal  Mind;  (2)  that 
the  world  of  our  abode  is  the  scene  of  a  moral  govern- 
ment, incipient  but  not  complete;  and  (3)  that  the 
upper  zones  of  human  affection,  above  the  clouds  of  self 
and  passion,  take  us  into  the  sphere  of  a  Divine  Commun- 
ion. Into  this  over-arching  scene  it  is  that  growing 
thought  and  enthusiasm  have  expanded  to  catch  their  light 
and  fire." 

Alpine  summits  seem  to  kindle  above  us  as  we  read 
these  glowing  words;  we  see  their  beauty  and  feel  their 
life.  At  the  close  of  one  of  the  essays  here  printed,*  I 
thus  refer  to  the  "Communion"  which  Mr.  Martineau 
calls  "Divine:"  "'Two  things/  said  Irnmanuel  Kant, 
'  fill  me  with  awe — 'the  starry  heavens,  and  the  sense  of 
moral  responsibility  in  man.'  And  in  his  hours  of  health 
and  strength  and  sanity,  when  the  stroke  of  action  has 
ceased,  and  the  pause  of  reflection  has  set  in,  the  scientific 
investigator  finds  himself  overshadowed  by  the  same  awe. 
Breaking  contact  with  the  hampering  details  of  earth, 
it  associates  him  with  a  power  which  gives  fullness  and  tone 
to  his  existence,  but  which  he  can  neither  analyze  nor 

*  "  Scientific  Use  of  the  Imagination." 


516  FRAGMENTS  OF  SCIENCE. 

comprehend."  Though  "knowledge"  is  here  disavowed, 
the  "  feelings  "  of  Mr.  Martineau  and  myself  are,  I  think, 
very  much  alike.  He,  nevertheless,  censures  me — almost 
denounces  me — for  referring  religion  to  the  region  of 
emotion.  Surely  he  is  inconsistent  here.  The  foregoing 
words  refer  to  an  inward  hue  or  temperature,  rather  than 
to  an  external  object  of  thought.  When  I  attempt  to  give 
the  Power  which  I  see  manifested  in  the  Universe  an  ob- 
jective form,  personal  or  otherwise,  it  slips  away  from 
me,  declining  all  intellectual  manipulation.  I  dare  not. 
save  poetically,  use  the  pronoun  "He"  regarding  it;  I 
dare  not  call  it  a  "Mind;"  I  refuse  to  call  it  even  a 
"  Cause."  Its  mystery  overshadows  me;  but  it  remains  a 
mystery,  while  the  objective  frames  which  some  of  my 
neighbors  try  to  make  it  fit,  seem  to  me  to  distort  and 
desecrate  it. 

It  is  otherwise  with  Mr.  Martineau,  and  hence  his  dis- 
content. He  professes  to  know  where  I  only  claim  to  feel. 
He  could  make  his  contention  good  against  me  if,  by  a 
process  of  verification,  he  would  transform  his  assumptions 
into  "  objective  knowledge."  But  he  makes  no  attempt  to 
do  so.  They  remain  assumptions  from  the  beginning  of 
his  address  to  its  end.  And  yet  he  frequently  uses  the 
word  "  unverified,"  as  if  it  were  fatal  to  the  position  on 
which  its  incidence  falls.  "The  scrutiny  of  Nature"  is 
one  of  his  sources  of  "  religious  faith;"  what  logical  foot- 
hold does  that  scrutiny  furnish,  on  which  any  one  of  the 
foregoing  three  assumptions  could  be  planted?  Nature, 
according  to  his  picturing,  is  base  and  cruel:  what  is  the 
inference  to  be  drawn  regarding  its  author?  If  nature  be 
"  red  in  tooth  and  claw,"  who  is  responsible?  On  a  mind- 
less nature  Mr.  Martineau  pours  the  full  torrent  of  his 
gorgeous  invective;  but  could  the  "  assumption  "  of ''an 
Eternal  Mind"-^-even  of  a  Beneficent  Eternal  Mind — render 
the  world  objectively  a  whit  less  mean  and  ugly  than  it  is? 
Not  an  iota.  It  is  man's  feelings,  and  not  external 
phenomena,  that  are  influenced  by  the  assumption. 
It  adds  not  a  ray  of  light  nor  a  strain  of  music  to  the 
objective  sum  of  things.  It  does  not  touch  the  phe- 
nomena of  physical  nature — storm,  flood,  or  fire — nor 
diminish  by  a  pang  the  bloody  combats  of  the  animal 
world.  But  it  does  add  the  glow  of  religious  emotion 
to  the  human  soul,  as  represented  by  Mr.  Martiueau, 


THE  REV.  JAMES  MARTINEAU.  517 

Beyond  this  I  defy  him  to  go;  and  yet  he  rashly — it 
might  be  said  petulantly — kicks  away  the  only  philosophic 
foundation  oil  which  it  is  possible  for  him  to  build  his 
religion. 

He  twits  incidentally  the  modern  scientific  interpretation 
of  nature  because  of  its  want  of  cheerfulness.  '"Let  the' 
new  future/'  he  says,  "preach  its  own  gospel,  and  devise, 
if  it  can,  the  means  of  making  the  tidings  glad."  This  is 
a  common  argument:  "If  you  only  knew  the  comfort  of 
belief!"  My  reply  is  that  I  choose  the  nobler  part  of 
Emerson,  when,  after  various  disenchantments,  he  ex- 
claimed, "I  covet  truth!"  The  gladness  of  true  heroism 
visits  the  heart  of  him  who  is  really  competent  to  say  this. 
Besides,  "gladness"  is  an  emotion,  and  Mr.  Martineau 
theoretically  scorns  the  emotional.  I  am  not,  however, 
acquainted  with  a  writer  who  draws  more  largely  upon  this 
source,  while  mistaking  it  for  something  objective.  "  To 
reach  the  Cause,"  he  says,"  there  is  no  need  to  go  into  the 
past,  as  though  being  missed  here,  He  could  be  found 
there.  But  when  once  He  has  been  apprehended  by 
the  proper  organs  of  divine  apprehension,  the  whole  life 
of  Humanity  is  recognized  as  the  scene  of  His  agency." 
That  Mr.  Martineau  should  have  lived  so  long,  thought  so 
much,  and  failed  to  recognize  the  entirely  subjective 
character  of  this  creed,  is  highly  instructive.  His  "  proper 
organs  of  divine  apprehension" — given,  we  must  assume, 
to  Mr.  Martineau  and  his  pupils,  but  denied  to  many  of 
the  greatest  intellects  and  noblest  men  in  this  and  other 
ages — lie  at  the  very  core  of  his  emotions. 

In  fact,  it  is  when  Mr.  Martineau  is  most  purely 
emotional  that  he  scorns  the  emotions:  it  is  when  he  is 
most  purely  subjective  that  he  rejects  subjectivity.  He 
pays  a  just  and  liberal  tribute  to  the  character  of  John 
Stuart  Mill.  But  in  the  light  of  Mill's  philosophy, 
benevolence,  honor,  purity,  having  "shrunk  into  mere 
unaccredited  subjective  susceptibilities,  have  lost  all 
support  from  Omniscient  approval,  and  all  presumable 
accordance  with  the  reality  of  things."  If  Mr.  Martineau 
had  given  them  any  inkling  of  the  process  by  which  he 
renders  the  "  subjective  susceptibilities  "  objective,  or  how 
he  arrivesat  an  objective  ground  of  "  Omniscient  approval," 
gratitude  from  his  pupils  would  have  been  his  just  meed. 
But,  as  it  is,  he  leaves  them  lost  in  an  iridescent  cloud  of 


518  FRAGMENTS  OF  SCIENCE. 

words,  after  exciting  a  desire  which  he  is  incompetent  to 
appease. 

"  We  are,"  he  says,  in  another  place,  "  forever  shaping 
onr  representations  of  invisible  tilings  into  forms  of  defi- 
nite opinion,  and  throwing  them  to  the  front,  as  if  they 
were  the  photographic  equivalent  of  our  real  faith.  It  is 
a  delusion  which  affects  us  all.  Yet  somehow  the  essence 
of  our  religion  never  finds  its  way  into  these  frames  of 
theory:  as  we  put  them  together  it  slips'  away,  and,  if  we 
turn  to  pursue  it,  still  retreats  behind;  ever  ready  to  work 
with  the  will,  to  unbind  and  sweeten  the  affections,  and 
bathe  the  life  with  reverence,  but  refusing  to  be  seen,  or 
to  pass  from  a  divine  hue  of  thinking  into  a  human  pattern 
of  thought."  This  is  very  beautiful,  and  mainly  so  because 
the  man  who  utters  it  obviously  brings  it  all  out  of  the 
treasury  of  his  own  heart.  But  the  "  hue  "  and  "  pattern  " 
here  so  finely  spoken  of,  the  former  refusing  to  pass  into 
the  latter,  are  neither  more  nor  less  than  that  "  emotion," 
en  the  one  hand,  and  that  "  objective  knowledge,"  on  the 
other,  which  have  drawn  this  suicidal  fire  from  Mr.  Marti- 
neau's  battery. 

I  now  come  to  one  of  the  most  serious  portions  of  Mr. 
Marfeiueau's  pamphlet — serious  far  less  on  account  of  its 
"personal  errors,"  than  of  its  intrinsic  gravity,  though  its 
author  has  thought  fit  to  give  it  a  witty  and  sarcastic  tone. 
He  analyzes  and  criticises  "  the  materialist  doctrine, 
which,  in  our  time,  is  proclaimed  with  so  much  pomp,  and 
resisted  with  so  much  passion.  *  Matter  is  all  I  want,' 
says  the  physicist;  'give  me  its  atoms  alone,  and  I  will 
explain  the  universe.' "  It  is  thought,  even  by  Mr. 
Martineau's  intimate  friends,  that  in  this  pamphlet  he  is 
answering  me.  I  must  therefore  ask  the  reader  to  con- 
trast the  foregoing  travesty  with  what  I  really  do  say 
regarding  atoms:  "  I  do  not  think  that  he  [the  materialist] 
is  entitled  to  say  that  his  molecular  groupings  and  motions 
explain  everything.  In  reality,  they  explain  nothing. 
The  utmost  he  can  affirm  is  the  association  of  two  classes 
of  phenomena,  of  whose  real  bond  of  union  he  is  in  abso- 
lute ignorance."*  This  is  very  different  from  saying, 
"  Give  me  its  atoms  alone,  and  I  will  explain  the  uni- 
verse." Mr.  Martineau  continues  his  dialogue  with  the 

*Address  on  ' '  Scientific  Materialism. " 


THE  RK V.  JAMKS  MA  RTlNEA  U.  519 

physicist:  "  '  Good,'  he  savs;  '  take  as  many  atoms  as 
you  please.  See  that" they  have  all  that  is  requisite  to  body 
[a  metaphysical  13],  being  homogeneous  extended  solids/ 
'  That  is  not  enough,' his  physicist  replies;  'it  might  do 
for  Democritus  and  the  mathematicians,  but  I  must  have 
something  more.  The  atoms  must  not  only  be  in  motion, 
and  of  various  shapes,  but  also  of  as  many  kinds  as  there 
are  chemical  elements;  for  how  could  I  efer  get  water  if  I 
had  only  hydrogen  elements  to  work  with?'  'So  be  it,' 
Mr.  Martineau  consents  to  answer,  '  only  this  is  a  con- 
siderable enlargement  of  your  specified  datum  [where,  and 
by  whom  specified?] — in  fact,  a  conversion  of  it  into 
several;  yet,  even  at  the  cost  of  its  monism  [put  into  it  by 
Mr.  Martineau],  your  scheme  seems  hardly  to  gain  its  end; 
for  by  what  manipulation  of  your  resources  will  you,  for 
example,  educe  Consciousness?"' 

This  reads  like  pleasantry,  but  it  deals  with  serious 
things.  For  the  last  seven  years  the  question  here  pro- 
posed by  Mr.  Martineau,  and  my  answer  to  it,  have  been 
accessible  to  all.  The  question,  in  my  words,  is  briefly 
this:  "  A  man  can  say,  '  1  feel,  1  think,  I  love,'  but  how 
does  consciousness  infuse  itself  into  the  problem?"  And 
here  is  my  answer:  The  passage  from  the  physics  of  the 
brain  to  the  corresponding  facts  of  consciousness  is  unthink- 
able. Granted  that  a  definite  thought  and  a  definite  molec- 
ular action  in  the  brain  occur  simultaneously;  we  do  not 
possess  the  intellectual  organ,  nor  apparently  any  rudi- 
ment of  the  organ,  which  would  enable  us  to  pass,  by  a 
process  of  reasoning,  from  the  one  to  the  other.  They 
appear  together,  but  we  do  not  know  why.  Were  our 
minds  and  senses  so  expanded,  strengthened,  and  illumi- 
natecl,  as  to  enable  us  to  see  and  feel  the  very  molecules  of 
the  brain;  were  we  capable  of  following  all  their  motion's, 
all  their  groupings,  all  their  electric  discharges,  if  such 
there  be;  and  were  we  intimately  acquainted  with  the  cor- 
responding states  of  thought  and  feeling,  we  should  be  as 
far  as  ever  from  the  solution  of  the  problem,  "How  are 
these  physical  processes  connected  with  the  facts  of  con- 
sciousness?" The  chasm  between  the  two  classes  of 
phenomena  would  still  remain  intellectually  impassable."  * 

*  Bishop  Butler's  reply  totlie  Lucretian  in  the  "  Belfast  Address  "  is 
all  in  the  same  strain. 


520  FHAQMUNT8  Off  SCIENCE. 

Compare  this  with  the  answer  which  Mr.  Martineau  puts 
into  tlie  mouth  of  his  physicist,  and  with  which  I  am 
generally  credited  by  Mr  Martineau's  readers,  both  in  Eng- 
land and  America:  "  '  It  [the  problem  of  consciousness] 
does  not  daunt  me  at  all.  Of  course  you  understand  that 
all  along  my  atoms  have  been  affected  by  gravitation  and 
polarity;  and  now  I  have  only  to  insist  with  Fechner  on  a 
difference  amoifg  molecules:  there  are  the  inorganic, 
which  can  change  only  their  place,  like  the  particles  in  an 
undulation;  and  there  are  the  organic,  which  can  change 
their  order,  as  in  a  globule  that  turns  itself  inside  out. 
With  an  adequate  number  of  these  our  problem  will  be 
manageable/  'Likely  enough/ we  may  say  ['entirely 
unlikely/  say  I],  '  seeing  how  careful  you  are  to  provide 
for  all  emergencies;  and  if  any  hitch  should  occur  in  the 
next  step,  where  you  will  have  to  pass  from  mere  sentiency 
to  thought  and  will,  you  can  again  look  in  upon  your 
atoms,  and  fling  among  them  a  handful  of  Leibnitz's 
monads,  to  serve  as  souls  in  little,  and  be  ready,  in  a  latent 
form,  with  that  Vorstellungs-fahigkeit  which  our  pictur- 
esque interpreters  of  nature  so  much  prize/" 

"But  surely,"  continues  Mr.  Martineau,  "you  must 
observe  that  this  'matter 'of  yours  alters  its  style  with 
every  change  of  service:  starting  as  a  beggar  with  scarce  a 
rag  of  'property'  to  cover  its  bones,  it  turns  up  as  a 
prince  when  large  undertakings  are  wanted.  'We  must 
radically  change  our  notions  of  matter/  says  Professor 
Tyndall;  and  then,  he  ventures  to  believe,  it  will  answer 
all  demands,  carrying  '  the  promise  and  potency  of  all 
terrestrial  life.'  If  the  measure  of  the  required  '  change 
iu  our  notions'  had  been  specified,  the  proposition  would 
have  had  a  real  meaning,  and  been  susceptible  of  a  test. 
It  is  easy  traveling  through  the  stages  of  such  an 
hypothesis;  you  deposit  at  your  bank  a  round  sum  ere  you 
start,  and,  drawing  on  it  piecemeal  at  every  pause,  com- 
plete your  grand  tour  without  a  debt." 

The  last  paragraph  of  this  argument  is  forcibly  and  ably 
stated.  On  it  I  am  willing  to  try  conclusions  with  Mr. 
Martineau.;  I  may  say,  in  parsing,  that  I  share  his  con- 
tempt for  the  picturesque  interpretation  of  •  nature,  if 
accuracy  of  vision  be  thereby  impaired.  But  the  term 
Vorstellungs-fahigkeit,  as  used  by  me,  means  the  power  of 
definite  mental  presentation,  of  attaching  to  words  the 


THE  REV.  JAMES  MARTINEAU.  521 

corresponding  objects  of  thought,  and  of  seeing  these  in 
their  proper  relations,  without  the  interior  haze  and  soft 
penumbral  borders  which  the  theologian  loves.  To  this 
mode  of  "  interpreting  nature,  "  I  shall  to  the. best  of  my 
ability  now  adhere. 

Neither  of  us,  I  trust,  will  be  afraid  or  ashamed  to  begin 
at  the  alphabet  of  this  question.  Our  first  effort  must  be 
to. understand  each  other,  and  this  'mutual  understanding 
can  only  be  ensured  by  beginning  low  down.  Physically 
speaking,  however,  we  need  not  go  below  the  sea-level. 
Let  us  then  travel  in  company  to  the  Caribbean  Sea,  and 
halt  upon  the  heated  water.  What  is  that  sea,  and  what 
is  the  sun  that  heats  it?  Ajisw^rlng:.fox--myself,  I  say  that 
they  are  both  matter.  I  fill  a  glass  with  the  sea- water  and 
expose  it  on  the~decTt~bf  the  vessel;  after  some  time  the 
liquid  has  all  disappeared,  and  left  a  solid  residue  of  salt 
in  the  glass  behind.  We  have  mobility,  invisibility — 
apparent  annihilation.  In  virtue  of 

The  glad  and  secret  aid 
The  sun  unto  the  ocean  paid, 

the  water  has  taken  to  itself  wings  and  flown  off  as  vapor. 
From  the  whole  surface  of  the  Caribbean  Sea  such  vapor  is 
rising;  and  now  we  must  follow  it — not  upon  our  legs, 
however,  nor  in  a  ship,  nor  even  in  a  balloon,  but  by  the 
mind's  eye — in  other  words,  by  that  power  of  Vorstellung 
which  Mr.  Martineau  knows  so  well,  and  which  he  so 
justly  scorns  when  it  indulges  in  loose  practices. 

Compounding,  then,  the  northward  motion  of  the  vapor 
with  the  earth's  axial  rotation,  we  track  our  fugitive 
through  the  higher  atmostpheric  regions,  obliquely  across 
the  Atlantic  Ocean  to  Western  Europe,  and  on  to  our 
familiar  Alps.  .Here  another  wonderful  metamorphosis 
occurs.  Floating  on  the  cold  cairn  air,  and  in  presence  of 
the  cold  firmament,  the  vapor  condenses,  not  only  to 
particles  of  water,  but  to  particles  of  crystalline  water. 
These  coalesce  to  staus  of  snow,  which  fall  upon  the  moun- 
tains in  forms  so  exquisite  that,  when  first  seen,  they  never 
fail  to  excite  rapture.  As  to  beauty,  indeed,  they  put  the 
work  of  the  lapidary  to  shame,  while  as  to  accuracy  they 
render  concrete  the  abstractions  of  the  geometer.  Are  these 
crystals  "matter?"  Without  presuming  to  dogmatize,  I 
answer  for  myself  in  the  affirmative. 


522  FRAGMENTS  OF  SCIENCE. 

Still,  a  formative  poiver  has  obviously  here  come  into 
play  which  did  not  manifest  itself  in  either  the  liquid  or 
the  vapor.  The  question  now  is,  was  not  the  power 
"  potential '.'  fhboth  of  them,  requiring  only  the  proper  con- 
ditions of  temperature  to  bring  it  into  action?  Again  I 
answer  for  myself  in  the  affirmative.  I  am,  however,  quite 
willing  to  discuss  with  Mr.  Martineau  the  alternative  hy- 
pothesis, that  an  imponderable  formative  soul  unites  itself 
with  the  substance  after  its  escape  from  the  liquid  state. 
If  he  should  espouse  this  hypothesis,  then  I  should  demand 
of  him  an  immediate  exercise  of  that  Vortellungs- 
fahigkeit,  with  which,  in  my  efforts  to  think  clearly,  I  can 
never  dispense.  I  should  ask,  at  what  moment  did  the 
soul  come  in?  Did  it  enter  at  once  or  by  degrees;  perfect 
from  the  first,  or  growing  and  perfecting  itself  contem- 
poraneously with  its  own  handiwork?  I  should  also  ask 
whether  it  is  localized  or  diffused?  Does  it  move  about  as 
a  lonely  builder,  putting  the  bits  of  solid  water  in  their 
places  as  soon  as  the  proper  temperature  has  set  in?  or  is 
it  distributed  through  the  entire  mass  of  the  crystal?  If  the 
latter,  then  the  soul  has  the  shape  of  the  crystal;  but  if  the 
former,  then  I  should  inquire  after  its  shape.  Has  it  legs 
or  arms?  If  not,  I  would  ask  it  to  be  made  clear  to  me  how 
a  thing  without  these  appliances  can  act  so  perfectly  the 
part  of  a  builder?  (I  insist  on  definition,  and  ask  unusual 
questions,  if  haply  I  might  thereby  banish  unmeaning 
words.)  What  were  the  condition  and  residence  of  the 
soul  before  it  joined  the  crystal?  What  becomes  of  it 
when  the  crystal  is  dissolved?  Why  should  a  particular 
temperature  be  needed  before  it  can  exercise  its  vocation? 
Finally,  is  the  problem  before  us  in  any  way  simplified  by 
the  assumption  of  its  existence?  I  think  it  probable  that, 
after  a  full  discussion  of  the  question,  Mr.  Martineau 
would  agree  with  me  in  ascribing  the  building  power 
displayed  in  the  crystal  to  the  bits  of  water  themselves. 
At  all  events,  I  should  count  upon  his  sympathy  so  far 
as  to  believe  that  he  would  consider  any  one  unman- 
nerly who  would  denounce  me  for  rejecting  this  notion 
of  a  separate  soul,  and  for  holding  the  snow-crystal  to  be 
"matter." 

But  then  what  an  astonishing  addition  is  here  made  to 
the  powers  of  matter!  AVho  would  have  dreamed,  without 
actually  seeing  its  work,  that  such  a  power  was  locked  up 


THK  HE  v.  JAMKS  MARTIN  EA  u.  523 

in  a  drop  of  water?  All  that  we  needed  to  make  the 
action  of  the  liquid  intelligible  was  the  assumption  of  Mr. 
Martineau's  "  homogeneous  extended  atomic  solids," 
smoothly  gliding  over  one  another.  But  had  we  supposed 
the  water  to  be  nothing  more  than  this,  we  should  have 
ignorantly  defrauded  it  of  an  intrinsic  architectural  power, 
which  the  art  of  man,  even  when  pushed  to  its  utmost  de- 
gree of  refinement,  is  incompetent  to  imitate.  I  would 
invite  Mr.  Martineau  to  consider  how  inappropiate  his 
figure  of  a  fictitious  bank  deposit  becomes  under  these 
circumstances.  The  "account  current"  of  matter  re- 
ceives nothing  at  my  hands  which  could  be  honestly 
kept  back  from  it.  If,  then,  "Democritus  and  the 
mathematicians"  so  defined  matter  as  to  exclude  the 
powers  here  proved  to  belong  to  it,  they  were  clearly  wrong, 
and  Mr.  Martineau,  instead  of  twitting  me  with  my  depar- 
ture from  them/  ought  rather  to  applaud  me  for  correcting 
them.* 

The  reader- of  my^ small  contributions  to  the  literature 
which  deals  with  the  overlapping  margins  of  science  and 
theology,  will  have  noticed  how  frequently  I  quote  Mr. 
Emerson.  I  do  so  mainly  because  in  him  we  have  a  poet 
and  a  profoundly  religious  man,  who  is  really  and  entirely 
undaunted  by  the  discoveries  of  science,  past,  present,  or 
prospective.  In  his  case  Poetry,  with  the  joy  of  a  bac- 
chanal, takes  her  graver  brother  Science  by  the  hand,  and 
cheers  him  with  immortal  laughter.  By  Emerson  scien- 
tific conceptions  are  continually  transmuted  into  the  finer 
forms  and  warmer  hues  of  an  ideal  world.  Our  present 
theme  is  touched  upon  in  the  lines: 

The  journeying  atoms,  primordial  wholes 
Firmly  draw,  firmly  drive  by  their  animate  poles. 

As  regards  veracity  and  insight  these  few  words  outweigh, 
in  my  estimation,  all  the  formal  learning  expended  by  Mr. 
Martineau  in  those  disquisitions  on  Force,  where  he  treats 
the  physicist  as  a  conjuror,  and  speaks  so  wittily  of  atomic 

*  Definition  implies  previous  examination  of  the  object  defined,  and 
is  open  to  correction  or  modification  as  knowledge  of  the  object  in- 
creases. Such  increased  knowledge  has  radically  changed  our  con- 
ceptions of  the  luminit'erous  ether,  converting  its  vibrations  from 
longitudinal  into  transverse.  Such  changes  also  Mr.  Martineau's 
conceptions  of  matter  are  doomed  to  undergo. 


524  FRAGMENTS  Of  SCIENCE. 

polarity.  In  fact,  without  this  notion  of  polarity — this 
"drawing"  and  "driving" — this  attraction  and  repulsion, 
we  stand  as  stupidly  dumb  before  the  phenomena  of  crys- 
tallization as  a  Bushman  before  the  phenomena  of  the  solar 
system.  The  genesis  and  growth  of  the  notion  I  have  en- 
deavored to  make  clear  in  my  third  Lecture  on  Light, 
and  in  the  article  on  "Matter  and  Force"  published  in 
this  volume. 

Our  further  course  is  here  foreshadowed.  A  Sunday  or 
two  ago  I  stood  under  an  oak  planted  by  Sir  John  Moore, 
the  hero  of  Oorunna.  On  the  ground  near  the  tree  little 
oaklets  were  successfully  fighting  for  life  with  the  surround- 
ing vegetation.  The  acorns  had  dropped  into  the  friendly 
soil,  and  this  was  the  result  of  their  interaction.  What  is 
the  acorn?  what  the  earth?  and  what  the  sun,  without 
whose  heat  and  light  the  tree  could  not  become  a  tree, 
however  rich  the  soil,  and  however  healthy  the  seed?  I 
answer  for  myself  as  before — all  "  matter."  And  the 
heat  and  light  which  here  play  so  potent  a  part  are 
acknowledged  to  be  motions  of  matter.  By  taking  some- 
thing much  lower  down  in  the  vegetable  kingdom  than 
the  oak,  we  might  approach  much  more  nearly  to  the  case 
of  crystallization  already  discussed;  but  this  is  not  now 
necessary. 

If,  instead  of  conceding  the  sufficiency  of  matter  here, 
Mr.  Marti neau  should  fly  to  the  hypothesis  of  a  vegetative 
soul,  all  the  questions  before  asked  in  relation  to  the  snow- 
star  become  pertinent.  I  would  invite  him  to  go  over  them 
one  by  one,  and  consider  what  replies  he  will  make  to 
them.  He  may  retort  by  asking  me,  "  Who  infused  the 
principle  of  life  into  the  tree?"  I  say,  in  answer,  that  our 
present  question  is  not  this,  but  another — not  who  made 
the  tree,  but  what  is  it?  Is  there  anything  besides  matter 
in  the  tree?  If  so,  what,  and  where?  Mr.  Martineau 
may  have  begun  by  this  time  to  discern  that  it  is  not 
"picturesqueness,"  but  cold  precision,  that  my  Vorstel- 
lungs-fahigkeit  demands.  How,  I  would  ask,  is  this 
vegetative  soul  to  be  presented  to  the  mind?  where  did 
it  flourish  before  the  tree  grew?  and  what  will  become 
of  it  when  the  tree  is  sawn  into  planks,  or  consumed  in 
fire? 

Possibly  Mr.  Martinean  may  consider  the  assumption  of 
this  soul  to  be  as  untenable  and  as  useless  as  I  do.  But 


T11E  REV.  JAMES  MARTINEA  U.  525 

then  if  the  power  to  build  a  tree  be  conceded  to  pure 
matter,  what  an  amazing  expansion  of  our  notions  of  the 
"  potency  of  matter  "  is  implied  in  the  concession!  Think 
of  tb.3  acorn,  of  the  earth,  and  of  the  solar  light  and  heat 
— was  ever  such  necromancy  dreamed  of  as  the  production 
of  that  massive  trunk,  those  swaying  boughs  and  whisper- 
ing leaves,  from  the  interaction  of  these  three  factors? 
In  this  interaction,  moreover,  consists  what  we  call  life. 
It  will  be  seen  that  I  am  not  in  the  least  insensible  to  the 
wonder  of  the  tree;  nay,  I  should  not  be  surprised  if,  in 
the  presence  of  this  wonder,  I  feel  more  perplexed  and 
overwhelmed  than  Mr.  Martiueau  himself. 

Consider  it  for  a  moment.  There  is  an  experiment, 
first  made  by  Wheatstone,  where  the  music  of  a  piano  is 
transferred  from  its  sound-board,  through  a  thin  wooden 
rod,  across  several  silent  rooms  in  succession,  and  poured 
out  at  a  distance  from  the  instrument.  The  strings  of  the 
piano  vibrate,  not  singly,  but  ten  at  a  time.  Every  string 
subdivides,  yielding  not  one  note,  but  a  dozen.  All  these 
vibrations  and  subvibrations  are  crowded  together  into  a 
bit  of  deal  not  more  than  a  quarter  of  a  square  inch  in 
section.  Yet  no  note  is  lost.  Each  vibration  asserts  its 
individual  rights;  and  all  are,  at  last,  shaken  forth  into 
the  air  by  a  second  sound-board,  against  which  the  distant 
end  of  the  rod  presses.  Thought  ends  in  amazement  when 
it  seeks  to  realize  the  motions  of  that  rod  as  the  music 
flows  through  it.  I  turn  to  my  tree  and  observe  its  roots, 
its  trunk,  its  branches,  and  its  leaves.  As  the  rod  conveys 
the  music,  and  yields  it  up  to  the  distant  air,  so  does  the 
trunk  convey  the  matter  and  the-  motion — the  shocks  and 
pulses  and  other  vital  actions — which  eventually  emerge  in 
the  umbrageous  foliage  of  the  tree.  I  went  some  time  ago 
through  the  greenhouse  of  a  friend.  He  had  ferns  from 
Ceylon,  the  branches  of  which  were  in  some  cases  not  much 
thicker  than  an  ordinary  pin — hard,  smooth,  and  cylin- 
drical— often  leafless  for  afoot  or  more.  But  at  the  end  of 
every  one  of  them  the  unsightly  twig  unlocked  the  exu- 
berant beauty  hidden  within  it,  and  broke  forth  into  a 
mass  of  fronds,  almost  large  enough  to  fill  the  arms.  We 
stand  here  upon  a  higher  level  of  the  wonderful:  we  are 
conscious  of  a  music  subtler  than  that  of  the  piano,  pass- 
ing unheard  through  these  tiny  boughs,  and  issuing  in 
what  Mr.  Martineau  would  opulently  call  the  "  clustered 


526  PR  A  GMENTS  0  F  SCTENCK. 

magnificence"  of  the  leaves.  Does  it  lessen  my  amaze- 
ment to  know  that  every  cluster,  and  every  leaf — their  form 
and  texture — lie,  like  the  music  in  the  rod,  in  the  molecular 
structure  of  these  apparently  insignificant  stems?  Not  so. 
Mr.  Martineau  weeps  for  "  the  beauty  of  the  flower  fad- 
ing into  a  necessity."  I  care  not  whether  it  comes  to  me 
through  necessity  or  through  freedom,  my  delight  in  it  is 
all  the  same.  I  see  what  he  sees  with  a  wonder  superadded. 
To  me,  as  to  him,  not  even  Solomon  in  all  his  glory  was 
arrayed  like  one  of  these. 

I  have  spoken  above  as  if  the  assumption  of  a  soul  would 
save  Mr.  Martineau  from  the  inconsistency  of  crediting 
pure  matter  with  the  astonishing  building  power  displayed 
in  crystals  and  trees.  This,  however,  would  not  be  the 
necessary  result;  for  it  would  remain  to  be  proved  that  the 
soul  assumed  is  not  itself  matter.  When  a  boy  I  learned 
from  Dr.  Watts  that  the  souls  of  conscious  brutes  are  mere 
matter.  And  the  man  who  would  claim  for  matter  the 
human  soul  itself,  would  find  himself  in  very  orthodox 
company.  "  All  that  is  created,"  says  Fauste,  a  famous 
French  bishop  of  the  fifth  century,  "  is  matter.  The  soul 
occupies  a  place;  it  is  enclosed  in  a  body;  it  quits  the  body 
at  death,  and  returns  to  it  at  the  resurrection,  as  in  the 
case  of  Lazarus;  the  distinction  between  hell  and  heaven, 
between  eternal  pleasures  and  eternal  pains,  proves  that, 
even  after  death,  souls  occupy  a  place  and  are  corporeal. 
G-od  only  is  incorporeal."  Tertullian,  moreover,  was  quite 
a  physicist  in  the  definiteness  of  his  conceptions  regarding 
the  soul.  "The  materiality  of  the  soul,"  he  says,  "  is 
evident  from  the  evangelists.  A  human  soul  is  there  ex- 
pressly pictured  as  suffering  in  hell;  it  is  placed  in  the 
middle  of  a  flame,  its  tongue  feels  a  cruel  agony,  and  it 
implores  a  drop  of  water  at  the  hands  of  a  happier  soul. 
Wanting  materiality,"  adds  Tertullian,  "  all  this  would  be 
without  meaning"*' 

*  The  foregoing  extracts,  which  M.  Alglave  recently  brought  to 
light  for  the  benefit  of  the  bishop  of  Orleans,  are  taken  from  the 
sixth  lecture  of  the  "  Cours  d'Histoire  Moderne"  of  that  most 
orthodox  of  statesmen,  M.  Guizot.  "  I  could  multiply,"  continues 
M.  Guizot,  "  these  citations  to  infinity,  and  they  prove  that  in  the 
first  centuries  of  our  era  the  materiality  of  the  soul  was  an  opinion 
not  only  permitted,  but  dominant."  Dr.  Moriarty,  and  the  synod 
which  he  recently  addressed,  obviously  forget  their  own  antecedents. 


THE  RE  V.  JA  MES  MA  R  TINKA  U.  527 

I  have  glanced  at  inorganic  nature — at  the  sea,  and  the 
sun,  and  the  vapor,  and  the  snow-flake,  and  at  organic 
nature  as  represented  by  the  fern  and  the  oak.  That  same 
sun  which  wanned  the  water  and  liberated  the  vapor, 
exerts  a  subtler  power  on  the  nutriment  of  the  tree.  It 
takes  hold  of  matter  wholly  unfit  for  the  purpose  of  nutri- 
tion, separates  its  nutritive  from  its  non-nutritive  portions, 
gives  the  former  to  the  vegetable,  and  carries  the  others 
away.  Planted  in  the  earth,  bathed  by  the  air,  and  tended 
by  the  sun,  the  tree  is  traversed  by  its  sap,  the  cells  are 
formed,  the  woody  fiber  is  spun,  and  the  whole  is  woven 
to  a  texture  wonderful  even  to  the  naked  eye,  but  a  million- 
fold  more  so  to  microscopic  vision.  Does  consciousness 
mix  in  any  way  with  these  processes?  No  man  can  tell. 
Our  only  ground  for  a  negative  conclusion  is  the  absence 
of  those  outward  manifestations  from  which  feeling  is  usu- 
ally inferred.  But  even  these  are  not  entirely  absent.  In 
the  greenhouses  of  Kew  we  may  see  that  a  leaf  can  close, 
in  response  to  a  proper  stimulus,  as  promptly  as  the  human 
fingers  themselves;  and  while  there  Dr.  Hooker  will  tell  us 
of  the  wondrous  fly-catching  and  fly-devouring  power  of 
the  Dionsea.  No  man  can  say  that  the  feelings  of  the 
animal  are  not  represented  by  a  drowsier  consciousness  in 
the  vegetable  world.  At  all  events,  no  line  has  ever  been 
drawn  between  the  conscious  and  the  unconscious;  for  the 
vegetable  shades  into  the  animal  by  such  fine  gradations, 
that  is  impossible  to  say  where  the  one  ends  and  the  other 
begins. 

In  all  such  inquiries  we  are  necessarily  limited  by  our 
own  powers:  we  observe  what  our  senses,  armed  with  the 
aids  furnished  by  science,  enable  us  to  observe;  nothing 
more.  The  evidences  as  to  consciousness  in  the  vegetable 
world  depend  wholly  upon  our  capacity  to  observe  and 
weigh  them.  Alter  the  capacity,  and  the  evidence  would 
alter  too.  Would  that  which  to  us  is  a  total  absence  of  any 
manifestation  of  consciousness  be  the  same  to  a  being  with 
our  capacities  indefinitely  multiplied?  To  such  a  being  I 
can  imagine  not  only  the  vegetable,  but  the  mineral  world, 
responsive  to  the  proper  irritants,  the  response  differing 

Their  boasted  succession  from  the  early  Church  renders  them  the 
direct  offspring  of  a,  "materialism  "  more  "  brutal  "  than  any  ever 
enunciated  by  me. 


528  VRA  QMENTS  OF  SCTKNCE. 

only  in  degree  from  those  exaggerated  manifestations, 
which,  in  virtue  of  their  magnitude,  appeal  to  our  weak 
powers  of  observation. 

Our  conclusion,  however,  must  be  based,  not  on  powers 
that  we  imagine,  but  upon  those  that  we  possess.  What  do 
they  reveal?  As  the  earth  and  atmosphere  offer  themselves 
as  the  nutriment  of  the  vegetable  world,  so  does  the  latter, 
which  contains  no  constituent  not  found  in  inorganic 
nature,  offer  itself  to  the  animal  world.  Mixed  with  cer- 
tain inorganic  substances — water,  for  example — the  vege- 
table constitutes,  in  the  long  run,  the  sole  sustenance  of 
the  animal.  Animals  may  be  divided  into  two  classes,  the 
first  of  which  can  utilize  the  vegetable  world  immediately, 
having  chemical  forces  strong  enough  to  cope  with  its 
most  refractory  parts;  the  second  class  use  the  vegetable 
world  mediately;  that  is  to  say,  after  its  finer  portions 
have  been  extracted  and  stored  up  by  the  first.  But  in 
neither  class  have  we  an  atom  newly  created.  The  animal 
world  is,  so  to  say,  a  distillation  through  the  vegetable 
world  from  inorganic  nature. 

From  this  point  of  view  all  three  worlds  would  constitute 
a  unity,  in  which  I  picture  life  as  immanent  everywhere. 
Nor  am  I  anxious  to  shut  out  the  idea  that  the  life  here 
spoken  of  may  be  but  a  subordinate  part  and  function  of 
a  Higher  Life,  as  the  living  moving  blood  is  subordinate  to 
the  living  man.  I  resist  no  such  idea  as  long  as  it  is  not 
dogmatically  imposed.  Left  for  the  human  mind  freely 
to  operate  upon,  the  idea  has  ethical  vitality;  but,  stiffened 
into  a  dogma,  the  inner  force  disappears,  and  the  out- 
ward yoke  of  a  usurping  hierarchy  takes  its  place. 

The  problem  before  us  is,  at  all  events,  capable  of 
definite  statement.  We  have  on  the  one  hand  strong 
grounds  for  concluding  that  the  earth  was  once  a  molten 
mass.  We  now  find  it  not  only  swathed  by  an  atmosphere, 
and  covered  by  a  sea,  but  also  crowded  with  living  things. 
The  question  is,  How  were  they  introduced?  Certainty 
may  be  as  unattainable  here  as  Bishop  Butler  held  it  to  be 
in  matters  of  religion;  but  in  the  contemplation  of  proba- 
b~  'ties  the  thoughtful  mind  is  forced  to  take  a  side.  The 
collusion  of  Science  which  recognizes  unbroken  causal  con- 
nection between  the  past  and  the  present  would  undoubtedly 
be  that  the  molten  earth  contained  within  it  elements  of 
life,  which  grouped  themselves  into  their  present  forms  as 


THE  REV.  JAMES  MARTINKAU.  529 

the  planet  cooled.  The  difficulty  and  reluctance  encoun- 
tered by  this  conception  arise  solely  from  the  fact  that  the 
theologic  conception  obtained  a  prior  footing  in  the  human 
mind.  Did  the  latter  depend  upon  reasoning  alone,  it 
could  not  hold  its  ground  for  an  hour  against  its  rival. 
But  it  is  warmed  into  life  and  strength  by  associated  hopes 
and  fears — and  not  only  by  these,  which  are  more  or  less 
mean,  but  by  that  loftiness  of  thought  and  feeling  which 
lifts  its  possessor  above  the  atmosphere  of  self,  and  which 
the  theologic  idea,  in  its  nobler  forms,  has  engendered  in 
noble  minds. 

Were  not  man's  origin  implicated,  we  should  accept 
without  a  murmur  the  derivation  of  animal  and  vegetable 
life  from  what  we  call  inorganic  nature.  The  conclusion 
of  pure  intellect  points  this  way  and  no  other.  But  the 
purity  is  troubled  by  our  interests  in  this  life,  and  by  our 
hopes  and  fears  regarding  the  life  to  come.  Reason  is 
traversed  by  the  emotions,  anger  rising  in  the  weaker  heads 
to  the  height  of  suggesting  that  the  suppression  of  the 
inquirer  by  the  arm  of  the  law  would  be  an  act  agreeable 
to  God,  and  serviceable  to  man.  But  this  foolishness  is 
more  than  neutralized  by  the  sympathy  of  the  wise;  and 
in  England  at  least,  so  long  as  the  courtesy  which  befits  an 
earnest  theme  is  adhered  to,  such  sympathy  is  ever  ready 
for  an  honest  man.  None  of  us  here  need  shrink  from 
saying  all  that  he  has  a  right  to  say.  We  ought,  however, 
to  remember  that  it  is  not  only  a  band  of  Jesuits,  weaving 
their  schemes  of  intellectual  slavery,  under  the  innocent 
guise  "  of  education,"  that  we  are  opposing.  Our  foes 
are  to  some  extent  of  our  own  household,  including  not 
only  the  ignorant  and  the  passionate,  but  a  minority  of 
minds  of  high  caliber  and  culture,  lovers  of  freedom, 
moreover,  who,  though  its  objective  liull  be  riddled  by 
logic,  still  find  the  ethic  life  of  their  religion  unimpaired". 
But  while  such  considerations  ought  to  influence  the  form 
of  our  argument,  and  prevent  it  from  ever  slipping  out  of 
the  region  of  courtesy  into  that  of  scorn  or  abuse,  its 
substance,  I  think,  ought  to  be  maintained  and  pre- 
sented in  unmitigated  strength. 

In  the  year  1855  the  chair  of  philosophy  in  the  Uni- 
versity of  Munich  happened  to  be  filled  by  a  Catholic 
priest  of  great  critical  penetration,  great  learning,  and 
great  courage,  who  had  borne  the  brunt  of  battle  long 


530  FRAGMENTS  OF  SCIENCE. 

before  Dollinger.  His  Jesuit  colleagues,  he  knew,  incul- 
cated the  belief  that  every  human  soul  is  sent  into  the 
world  from  God  by  a  separate  and  supernatural  act  of 
creation.  In  a  work  entitled  the  "Origin  of  the  Human 
Soul,"  Professor  Frohschamrner,  the  philosopher  here  al- 
luded to,  was  hardy  enough  to  question  this  doctrine,  and 
to  affirm  that  man,  body  and  soul,  comes  from  his  parents, 
the  act  of  creation  being,  therefore,  mediate  ami  secondary 
only.  The  Jesuits  keep  a  sharp  lookout  on  all  temerities 
of  this  kind;  and  their  organ,  the  "  Civilita  Cattolica," 
immediately  pounced  upon  Frohschamrner.  His  book  was 
branded  as  "  pestilent,"  placed  in  the  Index,  and  stamped 
with  the  condemnation  of  the  Church.*  The  Jesuit 
notion  does  not  err  on  the  score  of  indefiniteness.  Accord- 
ing to  it,  the  Power  whom  Goethe  does  not  dare  to  name, 
and  whom  Gassendi  and  Clerk  Maxwell  present  to  us  under 
the  guise  of  a  "  Manufacturer  "  of  atoms,  turns  out  annually, 
for  England  and  Wales  alone,  a  quarter  of  a  million  of  new 
souls.  Taken  in  connection  with  the  dictum  of  Mr. 
Carlyle,  that  this  annual  increment  to  our  population  are 
"  mostly  fools,"  but  little  profit  to  the  human  heart  seems 
derivable  from  this  mode  of  regarding  the  divine  oper- 
ations. 

But  if  the  Jesuit  notion  be  rejected,  what  are  we  to 
accept?  Physiologists  say  that  every  human  being  comes 
from  an  egg  not  more  than  the  one  hundred  and  twentieth 
of  an  inch  in  diameter.  Is  this  egg  matter?  I  hold  it  to 
be  so,  as  much  as  the  seed  of  a  fern  or  of  an  oak.  Nine 
months  go  to  the  making  of  it  into  a  man.  Are  the 
additions  made  during  this  period  of  gestation  drawn  from 
matter?  I  think  so  undoubtedly.  If  there  be  anything 
besides  matter  in  the  egg,  or  in  the  infant  subsequently 
slumbering  in  the  womb,  what  is  it?  The  questions 
already  asked  with  reference  to  the  stars  of  snow  may  be 
here  repeated.  Mr.  Martineau  will  complain  that  I  am 
disenchanting  the  babe  of  its  wonder;  but  is  this  the  case? 

*  King  Maximilian  II.  brought  Liebig  to  Munich,  he  helped 
Helmholtz  in  his  researches,  and  loved  to  liberate  and  foster  science. 
But  through  his  liberal  concession  of  power  to  the  Jesuits  in  the 
schools,  he  did  far  more  damage  to  the  intellectual  freedom  of  his 
country  than  his  superstitious  predecessor  Ludwig  I.  Priding  him- 
self on  being  a  German  prince,  Ludwig  would  not  tolerate  the  inter- 
ference of  the  Roman  party  with  the  political  affairs  of  Bavaria. 


THE  REV.  JAMES  MARTIN EAU.  531 

I  figure  it  growing  in  the  womb,  woven  by  a  something 
not  itself,  without  conscious  participation  on  the  part  of 
either  father  or  mother,  and  appearing  in  due  time  a  living 
miracle,  with  all  its  organs  and  all  their  implications. 
Consider  the  work  accomplished  during  these  nine  months 
in  forming  the  eye  alone — with  its  lens,  and  its  humors, 
and  its  miraculous  retina  behind.  Consider  the  ear  with 
its  tympanum,  cochlea,  and  Corti's  organ — an  instrument 
of  three  thousand  strings,  built  adjacent  to  the  brain,  and 
employed  by  it  to  sift,  separate,  and  interpret,  antecedent 
to  all  consciousness,  the  sonorous  tremors  of  the  external 
world.  All  this  has  been  accomplished,  not  only  without 
man's  contrivance,  but  without  his  knowledge,  the  secret 
of  his  own  organization  having  been  withheld  from  him 
since  his  birth  in  the  immeasurable  past,  until  these  latter 
days.  Matter  I  define  as  that  mysterious  thing  by  which 
all  this  is  accomplished.  How  it  came  to  have  this  power 
is  a  question  on  which  I  never  ventured  an  opinion.  If, 
then,  matter  starts  as  "  a  beggar,"  it  is,  in  my  view, 
because  the  Jacobs  of  theology  have  deprived  it  of  its 
birthright.  Mr.  Martineau  need  fear  no  disenchantment. 
Theories  of  evolution  go  but  a  short  way  toward  the  expla- 
nation of  this  mystery;  the  Ages,  let  us  hope,  will  at 
length  give  us  a  poet  competent  to  deal  with  it  aright. 

There  are  men,  and  they  include  among  them  some  of 
the  best  of  the  race  of  man.  upon  whose  minds  this  mystery 
falls  without  producing  either  warmth  or  color.  The  "  dry 
light"  of  the  intellect  suffices  for  them,  and  they  live 
their  noble  lives  untouched  by  a  desire  to  give  the  mystery 
shape  or  expression.  There  are,  on  the  other  hand,  men 
whose  minds  are  warmed  and  colored  by  its  presence,  and 
who,  under  its  stimulus,  attain  to  moral  heights  which  have 
never  been  overtopped.  Different  spiritual  climates  are 
necessary  for  the  healthy  existence  of  these  two  classes  of 
men;  and  different  climates  must  be  accorded  them.  The 
history  of  humanity,  however,  proves  the  experience  of  the 
second  class  to  illustrate  the  most  pervading  need.  The 
world  will  have  religion  of  some  kind,  even  though  it 
should  fly  for  it  to  the  intellectual  whoredom  of  "spirit- 
ualism." What  is  really  wanted  is  the  lifting  power  of  an 
ideal  element  in  human  life.  But  the  free  play  of  this 
power  must  be  preceded  bv  its  release  from  the  practical 
materialism  of  the  present,  as  well  as  from  the  torn 


532  FRAGMENTS  OF  SCIENCE. 

swaddling  bands  of  the  past.  It  is  now  in  danger  of  being 
stupefied  by  the  one,  or  strangled  by  the  other.  I  look, 
however,  forward  to  a  time  when  the  strength,  insight, 
and  elevation  which  now  visit  us  in  mere  hints  and 
glimpses,  during  moments  "of  clearness  and  vigor,"  shall 
be  the  stable  and  permanent  possession  of  purer  and 
mightier  minds  than  ours — purer  and  mightier,  partly 
because  of  their  deeper  knowledge  of  matter  and  their 
more  faithful  conformity  to  its  laws. 


CHAPTER  XXXIV. 

FERMENTATION,    AND   ITS   BEARINGS  ON    SURGERY  AND 
MEDICINE.* 

ONE  OF  the  most  remarkable  characteristics  of  the  age 
in  which  we  live,  is  its  desire  and  tendency  to  connect 
itself  organically  with  preceding  ages — to  ascertain  how 
the  state  of  things  that  now  is  came  to  be  what  it  is.  And 
the  more  earnestly  and  profoundly  this  problem  is  studied, 
the  more  clearly  comes  into  view  the  vast  and  varied  debt 
which  the  world  of  to-day  owes  to  that  fore-world,  in 
which  man  by  skill,  valor,  and  well-directed -strength  first 
replenished  and  subdued  the  earth.  Our  prehistoric 
fathers  may  have  been  savages,  but  they  were  clever  and 
observant  ones.  They  founded  agriculture  by  the  dis- 
covery and  development  of  seeds  whose  origin  is  now  un- 
known. They  tamed  and  harnessed  their  animal  antag- 
onists, and  sent  them  down  to  us  as  ministers,  instead  of 
rivals  in  the  fight  for  life.  Later  on,  when  the  claims  of 
luxury  added  themselves  to  those  of  necessity,  we  find  the 
same  spirit  of  invention  at  work.  We  have  no  historic 
account  of  the  first  brewer,  but  we  glean  from  history  that 
his  art  was  practiced,  and  its  produce  relished,  more  than 
two  thousand  years  ago.  Theophrastus,  who  was  born 
nearly  four  hundred  years  before  Christ,  described  beer  as 
the  wine  of  barley.  It  is  extremely  difficult  to  preserve 
beer  in  a  hot  country,  still  Egypt  was  the  land  in  which  it 
was  first  brewed,  the  desire  of  man  to  quench  his  thirst 

*  A   Discourse   delivered   before    the   Glasgow    Science    Lectures 
Association,  October  19,  1876. 


FERMENTATION.  533 

with  this  exhilarating  beverage  overcoming  all  the  obstacles 
which  a  hot  climate  threw  in  the  way  of  its  manufacture. 

Our  remote  ancestors  had  also  learned  by  experience  that 
wine  maketh  glad  the  heart  of  man.  Noah,  we  are 
informed,  planted  a  vineyard,  drank  of  the  wine,  and 
experienced  the  consequences.  But,  though  wine  and  beer 
possess  so  old  a  history,  a  very  few  years  ago  no  man  knew 
the  secret  of  their  formation.  Indeed,  it  might  be  said 
that  until  the  present  year  no  thorough  and  scientific 
account  was  ever  given  of  the  agencies  which  come  into 
play  in  the  manufacture  of  beer,  of  the  conditions  necessary 
to  its  health,  and  of  the  maladies  and  vicissitudes  to  which 
it  is  subject.  Hitherto  the  art  and  practice  of  the  brewer 
have  resembled  those  of  the  physician,  both  being  founded 
on  empirical  observation.  By  this  is  meant  the  obser- 
vation of  facts,  apart  from  the  principles  which  explain 
them,  and  which  give  the  mind  an  intelligent  mastery 
over  them.  The  brewer  learned  from  long  experience  the 
conditions,  not  the  reasons,  of  success.  But  he  had  to 
contend,  and  has  still  to  contend,  against  unexplained  per- 
plexities. Over  and  over  again  his  care  has  been  rendered 
nugatory;  his  beer  has  fallen  into  acidity  or  rottenness,  and 
disastrous  losses  have  been  sustained,  of  which  he  has  been 
unable  to  assign  the  cause.  It  is  the  hidden  enemies 
against  which  the  physician  and  the  brewer  have  hitherto 
contended,  that  recent  researches  are  dragging  into  the 
light  of  day,  thus  preparing  the  way  for  their  final  exter- 
mination. 

Let  us  glance  for  a  moment  at  the  outward  and  visible 
signs  of  fermentation.  A  few  weeks  ago  I  paid  a  visit  to 
a  private  still  in  a  Swiss  chalet;  and  this  is  what  I  saw. 
In  the  peasant's  bedroom  was  a  cask  with  a  very  large 
bunghole  carefully  closed.  The  cask  contained  cherries 
which  had  lain  in  it  for  fourteen  days.  It  was  not  entirely 
filled  with  the  fruit,  an  air-space  being  left  above  the 
cherries  when  they  were  put  in.  I  had  the  bung  removed, 
and  a  small  lamp  dipped  into  this  space.  Its  flame  was 
instantly  extinguished.  The  oxygen  of  the  air  had  entirely 
disappeared,  its  place  being  taken  by  carbonic  acid  gas.* 

*The  gas  which  is  exhaled  from  the  lungs  after  the  oxygen  of  the 
air  has  done  its  duty  in  purifying  the  blood,  the  same  also  which 
effervesces  from  soda  water  and  champagne. 


534  FRAGMENTS  OF  SCIENCE. 

I  tasted  the  cherries:  they  were  very  sour,  though  when 
put  into  the  cask  they  were  sweet.  The  cherries  and  the 
liquid  associated  with  them  were  then  placed  in  a  copper 
boiler,  to  which  a  copper  head  was  closely  fitted.  From 
the  head  proceeded  a  copper  tube  which  passed  straight 
through  a  vessel  of  cold  water,  and  issued  at  the  other  side. 
Under  the  open  end  of  the  tube  was  placed  a  bottle  to 
receive  the  spirit  distilled.  The  flame  of  small  wood- 
splinters  being  applied  to  the  boiler,  after  a  time  vapor 
rose  into  the  head,  passed  through  the  tube,  was  condensed 
by  the  cold  of  the  water,  and  fell  in  a  liquid  fillet  into  the 
bottle.  On  being  tasted,  it  proved  to  be  that  fiery  and 
intoxicating  spirit  known  in  commerce  as  Kirsch  or 
Kirschwasseri 

The  cherries,  it  should  be  remembered,  were  left  to 
themselves,  no  ferment  of  any  kind  being  added  to  them. 
In  this  respect  what  has  been  said  of  the  cherry  applies 
also  to  the  grape.  At  the  vintage  the  fruit  of  the  vine  is 

? laced  in  proper  vessels,  and  abandoned  to  its  own  action, 
t  ferments,  producing  carbonic  acid;  its  sweetness  disap- 
pears, and  at  the  end  of  a  certain  time  the  uniutoxicating 
grape-juice  is  converted  into  intoxicating  wine.  Here, 
as  in  the  case  of  the  cherries,  the  fermentation  is  spon- 
taneous— in  what  sense  spontaneous  will  appear  more 
clearly  by  and  by. 

It  is  needless  for  me  to  tell  a  Glasgow  audience  that  the 
beer-brewer  does  not  set  to  work  in  this  way.  In  the  first 
place  the  brewer  deals  not  with  the  juice  of  fruits,  but 
with  the  juice  of  barley.  The  barlev  having  been  steeped 
for  a  sufficient  time  in  water,  it  is  drained  and  subjected 
to  a  temperature  sufficient  to  cause  the  moist  grain  to 
germinate;  after  which,  it  is  completely  dried  upon  a  kiln. 
It  then  receives  the  name  of  malt.  The  malt  is  crisp  to 
the  teeth,  and  decidedly  sweeter  to  the  taste  than  the 
original  barley.  It  is  ground,  mashed  up  in  warm  water, 
then  boiled  with  hops  until  all  the  soluble  portions  have 
been  extracted;  the  infusion  thus  produced  being  called 
the  wort.  This  is  drawn  off,  and  cooled  as  rapidly  as 
possible;  then,  instead  of  abandoning  the  infusion,  as  the 
wine-maker  does,  to  its  own  action,  the  brewer  mixes  yeast 
with  his  wort,  and  places  it  in  vessels  each  with  only  one 
aperture  open  to  the  air.  Soon  after  the  addition  to  the 
yeast,  a  brownish  froth,  which  is  really  new  yeast,  issues 


FERMENTATION.  535 

from  the  aperture,  and  falls  like  a  cataract  into  troughs 
prepared  to  receive  it.  This  frothing  and  foaming  of  the 
wort  is  a  proof  that  the  fermentation  is  active. 

Whence  comes  the  yeast  which  issues  so  copiously  from 
the  fermenting  tub?  What  is  this  yeast,  and  how  did  the 
brewer  become  possessed  of  it?  Examine  its  quantity 
before  and  after  fermentation.  The  brewer  introduces, 
say  10  cwts.  of  yeast;  he  collects  40,  or  it  may  be  50  cwts. 
The  yeast  has,  therefore,  augmented  from  four  to  fivefold 
during  the  fermentation.  Shall  we  conclude  that  this 
additional  yeast  has  been  spontaneously  generated  by  the 
wort?  Are  we  not  rather  reminded  of  that  seed  which  fell 
into  good  ground,  and  brought  forth  fruit,  some  thirty- 
fold,  some  sixtyfold,  some  an  hundredfold?  On  exami- 
nation, this  notion  of  organic  growth  turns  out  to  be  more 
than  a  mere  surmise.  In  the  year  1680,  when  the  micro- 
scope was  still  in  its  infancy,  Leeuwenhoek  turned  the 
instrument  upon  this  substance,  and  found  it  composed  of 
minute  globules  suspended  in  a  liquid.  Thus  knowledge 
rested  until  1835,  when  Cagniard  de  la  Tour  in  France,  and 
Schwanu  in  Germany,  independently,  but  animated  by  a 
common  thought,  turned  microscopes  of  improved  defini- 
tion and  heightened  powers  upon  yeast,  and  found  it  bud- 
ding and  sprouting  before  their  eyes.  The  augmentation 
of  the  yeast  alluded  to  above  was  thus  proved  to  arise  from 
the  growth  of  a  minute  plant  now  called  Tornla  (or 
Saccharomyces)  Cerevisice,  Spontaneous  generation  is 
therefore  out  of  the  question.  The  brewer  deliberately 
sows  the  yeast-plant,  which  grows  and  multiplies  in  the 
wort  as  its  proper  soil.  This  discovery  marks  an  epoch  in 
the  history  of  fermentation. 

But  where  did  the  brewer  find  his  yeast?  The  reply  to 
this  question  is  similar  to  that  which  must  be  given  if  it 
were  asked  wliere  the  brewer  found  his  barley.  He  has 
received  the  seeds  of  both  of  them  from  preceding  genera- 
tions. Could  we  connect  without  solution  of  continuity 
the  present  with  the  past,  we  should  probably  be  able  to 
trace  back  the  yeast  employed  by  my  friend  Sir  Fowell 
Buxton  to-day  to  that  employed  by  some  Egyptian  brewer 
two  thousand  years  ago.  But  you  may  urge  that  there 
must  have  been  a  time  when  the  first  yeast-cell  was  gen- 
erated. Granted — exactly  as  there  was  a  time  when  the 
first  barley-corn  was  generated.  Let  not  the  delusion  lay 


536  FRA  GMENTS  0 F  SCIENCE. 

hold  of  you  that  a  living  thing  is  easily  generated  because 
it  is  small.  Both  the  yeast-plant  and  the  barley-plant  lose 
themselves  in  the  dim  twilight  of  antiquity,  and  in  this 
our  day  there  is  no  more  proof  of  the  spontaneous  genera- 
tion of  the  one,  than  there  is  of  the  spontaneous  generation 
of  the  other. 

I  stated  a  moment  ago  that  the  fermentation  of  grape- 
juice  was  spontaneous;  but  I  was  careful  to  add,  "  in  what 
sense  spontaneous  will  appear  more  clearly  by  and  by." 
Now  this  is  the  sense  meant.  The  wine-maker  does  not, 
like  the  brewer  and  distiller,  deliberately  introduce  either 
yeast,  or  any  equivalent  of  yeast,  into  his  vats;  he  does  not 
consciously  "sow  in  them  any  plant,  or  the  germ  of  any 
plant;  indeed,  he  has  been  hitherto  in  ignorance  whether 
plants  or  germs  of  any  kind  have  had  anything  to  do  with 
his  operations.  Still,  when  the  fermented  grape-juice  is 
examined,  the  living  Torula  concerned  in  alcoholic  fermen- 
tation never  fails  to  make  its  appearance.  How  is  this? 
If  no  living  germ  has  been  introduced  into  the  wine-vat, 
whence  comes  the  life  so  invariably  developed  there? 

You  may  be  disposed  to  reply,  with  Turpin  and  others, 
that  in  virtue  of  its  own  inherent  powers,  the  grape-juice 
when  brought  into  contact  with  the  vivifying  atmospheric 
oxygen,  runs  spontaneously  and  of  its  own  accord  into 
these  low  forms  of  life.  I  have  not  the  slightest  objection 
to  this  explanation,  provided  proper  evicence  can  be 
adduced  in  support  of  it.  But  the  evidence  adduced  in 
its  favor,  as  far  as  I  am  acquainted  with  it,  snaps  asunder 
under  the  strain  of  scientific  criticism.  It  is,  as  far  as  I 
can  see,  the  evidence  of  men,  who  however  keen  and 
clever  as  observers,  are  not  rigidly  trained  experimenters. 
These  alone  are  aware  of  the  precautions  necessary  in 
investigations  of  this  delicate  kind.  In  reference,  then, 
to  the  life  of  the  wine-vat,  what  is  the  decision  of  experi- 
ment when  carried  out  by  competent  men?  Let  a  quantity 
of  the  clear,  filtered  ",  must"  of  the  grape  be  so  boiled  as 
to  destroy  such  germs  as  it  may  have  contracted  from  the 
air  or  otherwise.  In  contact  with  germless  air  the  uncon- 
taminated  must  never  ferment.  All  the  materials  for 
spontaneous  generation  are  there,  but  so  long  as  there  is 
no  seed  sown,  there  is  no  life  developed,  and  no  sign  of 
that  fermentation  which  is  the  concomitant  of  life.  Nor 
need  you  resort  to  a  boiled  liquid.  The  grape  is  sealed  by 


FERMENTATION.  537 

• 

its  own  skin  against  contamination  from  without.  By  an 
ingenious  device  Pasteur  has  extracted  from  the  interior  of 
the  grape  its  pure  juice,  and  proved  that  in  contact  with 
pure  air  it  never  acquires  the  power  to  ferment  itself,  nor 
to  produce  fermentation  in  other  liquids.*  It  is  not 
therefore,  in  the  interior  of  the  grape  that  the  origin  of 
the  life  observed  in  the  vat  is  to  be  sought. 

What  then  is  its  true  origin?  This  is  Pasteur's  answer, 
which  his  well-proved  accuracy  renders  worthy  of  all  con- 
fidence. At  the  time  of  the  vintage  microscopic  particles 
are  observed  adherent,  both  to  the  outer  surface  of  the 
grape  and  of  the  twigs  which  support  the  grape.  Brush 
these  particles  into  a  capsule  of  pure  water.  It  is  rendered 
turbid  by  the  dust.  Examined  by  a  microscope,  some  of 
these  minute  particles  are  seen  to  present  the  appearance 
of  organized  cells.  Instead  of  receiving  them  in  water, 
let  them  be  brushed  into  the  pure  inert  juice  of  the  grape. 
Forty-eight  hours  after  this  is  done,  our  familiar  Torula  is 
observed  budding  and  sprouting,  the  growth  of  the  plant 
being  accompanied  by  all  the  other  signs  of  active  fermen- 
tation. What  is  the  inference  to  be  drawn  from  this  ex- 
periment? Obviously  that  the  particles  adherent  to  the 
external  surface  of  the  grape  include  the  germs  of  that  life 
which,  after  they  have  been  sown  in  the  juice,  appears  in 
such  profusion.  Wine  is  sometimes  objected  to  on  the 
ground  that  fermentation  is  "  artificial;  "  but  we  notice 
here  the  responsibility  of  nature.  The  ferment  of  the  grape 
clings  like  a  parasite  to  the  surface  of  the  grape;  and  the 
art  of  the  wine-maker  from  time  immemorial  has  consisted 
in  bringing — and  it  may  be  added,  ignorantly  bringing — 
two  things  thus  closely  associated  by  nature  into  actual 
contact  with  each  other.  For  thousands  of  years,  what  has 
been  done  consciously  by  the  brewer,  has  been  done  uncon- 
sciously by  the  wine-grower.  The  one  has  sown  his  leaven 
just  as  much  as  the  other. 

Nor  it  is  necessary  to  impregnate  the  beer- wort  with 
yeast  to  provoke  fermentation.  Abandoned  to  the  contact 
of  our  common  air,  it  sooner  or  later  ferments;  but  the 


*The  liquids  of  the  healthy  animal  body  are  also  sealed  from  ex- 
ternal contamination.  Pure  blood,  for  example,  drawn  with  due 
precautions  from  the  veins,  will  never  ferment  or  putrefy  in  contact 
with  pure  air. 


538  VRA  GMENTS  OF  SCIENCE. 

chances  are  that  the  produce  of  that  fermentation,  instead 
of  being  agreeable,  would  be  disgusting  to  the  taste.  By 
a  rare  accident  we  might  get  the  true  alcoholic  fermenta- 
tion, but  the  odds  against  obtaining  it  would  be  enormous. 
Pure  air  acting  upon  a  lifeless  liquid  will  never  provoke 
fermentation;  but  our  ordinary  air  is  the  vehicle  of 
numberless  germs  which  act  as  ferments  when  they  fall 
into  appropriate  infusions.  Some  of  them  produce 
acidity,  some  putrefaction.  The  germs  of  our  yeast- 
plant  are  also  in  the  air;  but  so  sparingly  distributed  that 
an  infusion  like  beer-wort,  exposed  to  the  air,  is  almost 
sure  to  be  taken  possession  of  by  foreign  organisms. 
In  fact,  the  maladies  of  beer  are  wholly  due  to  the  ad- 
mixture of  these  objectionable  ferments,  whose  forms  and 
modes  of  nutrition  differ  materially  from  those  of  the  true 
leaven. 

Working  in  an  atmosphere  charged  with  the  germs  of 
these  organisms,  you  can  understand  how  easy  it  is  to  fall 
into  error  in  studying  the  action  of  any  one  of  them. 
Indeed  it  is  only  the  most  accomplished  experimenter,  who, 
moreover,  avails  himself  of  every  means  of  checking  his 
conclusions,  that  can  walk  without  tripping  through  this 
land  of  pitfalls.  Such  a  man  the  French  chemist  Pasteur 
has  hitherto  proved  himself  to  be.  He  has  taught  us  how 
to  separate  the  commingled  ferments  of  our  air,  and  to 
study  their  pure  individual  action.  Guided  by  him,  let  us 
fix  our  attention  more  particularly  upon  the  growth  and 
action  of  the  true  yeast-plant  under  different  conditions. 
Let  it  be  sown  in  a  fermentable  liquid,  which  is  supplied 
with  plenty  of  pure  air.  The  plant  will  flourish  in  the 
aerated  infusion,  and  produce  large  quantities  of  carbonic 
acid  gas — a  compound,  as  you  know,  of  carbon  and 
oxygen.  The  oxygen  thus  consumed  by  the  plant  is  the 
free  oxygen  of  the  air,  which  we  suppose  to  be  abundantly 
supplied  to  the  liquid.  The  action  is  so  far  similar 
to  the  respiration  of  animals,  which  inspire  oxygen  and 
expire  carbonic  acid.  Jf  we  examine  the  liquid  even 
when  the  vigor  of  the  plant  has  reached  its  maximum, 
we  hardly  find  in  it  a  trace  of  alcohol.  The  yeast  has 
grown  and  flourished,  but  it  has  almost  ceased  to  act  as 
a  ferment.  And  could  every  individual  yeast-cell  seize, 
without  any  impediment,  free  oxygen  from  the  surrounding 
liquid,  it  is  certain  that  it  would  cease  to  act  as  a  ferment 
altogether. 


FERMENTATION.  539 

What,  then,  are  the  conditions  under  which  the  yeast- 
plant  must  be  placed  so  that  it  may  display  its  character- 
istic quality?  Reflection  on  the  facts  already  referred  to 
suggests  a  reply,  and  rigid  experiment  confirms  the  sug- 
gestion. Consider  the  Alpine  cherries  in  their  closed 
vessel.  Consider  the  beer  in  its  barrel,  with  a  single  small 
aperture  open  to  the  air,  through  which  it  is  observed  not 
to  imbibe  oxygen,  but  to  pour  forth  carbonic  acid.  Whence 
come  the  volumes  of  oxygen  necessary  to  the  production 
of  this  latter  gas?  The  small  quantity  of  atmospheric  air 
dissolved  in  the  wort  and  overlying  it  would  be  totally 
incompetent  to  supply  the  necessary  oxygen.  In  no  other 
Avay  can  the  yeast-plant  obtain  the  gas  necessary  for  its 
respiration  than  by  wrenching  it  from  surrounding  sub- 
stances in  which  the  oxygen  exists,  not  free,  but  in  a  state 
of  combination.  It  decomposes  the  sugar  of  the  solution 
in  which  it  grows,  produces  heat,  breathes  forth  carbonic 
acid  gas,  and  one  of  the  liquid  products  of  the  decomposi- 
tion is  on  r  familiar  alcohol.  The  act  of  fermentation,  then, 
is  a  result  of  the  effort  of  the  little  plant  to  maintain  its 
respiration  by  means  of  combined  oxygen,  when  its  supply 
of  free  oxygen  is  cutoff.  As  defined  by  Pasteur,  fermenta- 
tion is  life  without  air. 

But  here  the  knowledge  of  that  thorough  investigator 
comes  to  our  aid  to  warn  us  against  errors  which  have  been 
committed  over  and  over  again.  It  is  not  all  yeast-cells 
that  can  thus  live  without  air  and  provoke  fermentation. 
They  must  be  young  cells  which  have  caught  their 
vegetative  vigor  from  contact  with  free  oxygen.  But 
once  possessed  of  this  vigor  the  yeast  may  be  trans- 
planted into  a  saccharine  infusion  absolutely  purged  of 
air,  where  it  will  continue  to  live  at  the  expense  of  the 
oxygen,  carbon,  and  other  constituents  of  the  infusion. 
Under  these  new  conditions  its  life,  as  a  plant,  will  be 
by  no  means  so  vigorous  as  when  it  had  a  supply  of  free 
oxygen,  but  its  action  as  a  ferment  will  be  indefinitely 
greater. 

Does  the  yeast-plant  stand  alone  in  its  power  of  pro- 
voking alcoholic  fermentation?  It  would  be  singular  if 
amid  the  multitude  of  low  vegetable  forms  no  other  could 
be  found  capable  of  ac.ting  in  a  similar  way.  And  here 
again  we  have  occasion  to  marvel  at  that  sagacity  of  obser- 
vation among  the  ancients  to  which  we  owe  so  vast  a  debt. 


540  FRAGMENTS  OF  SCIENCE. 

Not  only  did  they  discover  the  alcoholic  ferment  of  yeast, 
but  they  had  to  exercise  a  wise  selection  in  picking  it  out 
from  others,  and  giving  it  special  prominence.  Place  an 
old  boot  in  a  moist  place,  or  expose  common  paste  or  a  pot 
of  jam  to  the  air;  it  soon  becomes  coated  with  a  blue-green 
mold,  which  is  nothing  else  than  the  fructification  of  a 
little  plant  called  Penicillium  glaucum.  Do  not  imagine 
that  the  mold  has  sprung  spontaneously  from  boot,  or 
paste,  or  jam;  its  germs,  which  are  abundant  in  the 
air,  have  been  sown,  and  have  germinated,  in  as  legal  and 
legitimate  a  way  as  thistle-seeds  wafted  by  the  wind  to  a 
proper  soil.  Let  the  minute  spores  of  Penicillinm  be  sown 
in  a  fermentable  liquid,  which  has  been  previously  so 
boiled  as  to  kill  all  other  spores  or  seeds  which  it  may  con- 
tain; let  pure  air  have  free  access  to  the  mixture;  the 
Penicillinm  will  grow  rapidly,  striking  long  filaments  inta 
the  liquid,  and  fructifying  at  its  surface.  Test  the 
infusion  at  various  stages  of  the  plant's  growth,  you  will 
never  find  in  it  a  trace  of  alcohol.  But  forcibly  submerge 
the  little  plant,  push  it  down  deep  into  the  liquid,  where 
the  quantity  of  free  oxygen  that  can  reach  it  is  insufficient 
for  its  needs,  it  immediately  begins  to  act  as  a  ferment, 
supplying  itself  with  oxygen  by  the  decomposition  of  the 
sugar,  and  producing  alcohol  as  one  of  the  results  of  the 
decomposition.  Many  other  low  microscopic  plants  act  in 
a  similar  manner.  In  aerated  liquids  they  flourish  without 
any  production  of  alcohol,  but  cut  off  from  free  oxygen 
they  act  as  ferments,  producing  alcohol  exactly  as  the  real 
alcoholic  leaven  produces  it,  only  less  copiously.  For  the 
right  apprehension  of  all  these  facts  we  are  indebted  to 
Pasteur. 

In  the  cases  hitherto  considered,  the  fermentation  is 
proved  to  be  the  invariable  correlative  of  life,  being  pro- 
duced by  organisms  foreign  to  the  fermentable  substance. 
But  the  substance  itself  may  also  have  within  it,  to  some 
extent,  the  motive  power  of  fermentation.  The  yeast- 
plant,  as  we  have  learned,  is  an  assemblage  of  living  cells; 
but  so  at  bottom,  as  shown  by  Schleiden  and  Schwann, 
are  all  living  organisms.  Cherries,  apples,  peaches,  pears, 
plums,  and  grapes,  for  example,  are  composed  of  cells, 
each  of  which  is  a  living  unit.  And  here  I  have  to  direct 
your  attention  to  a  point  of  extreme  interest.  In  1821, 
the  celebrated  French  chemist,  B6ra.rd.,  established  the 


FERMENTATION.  541 

important  fact  that  all  ripening  fruit,  exposed  to  the  free 
atmosphere,  absorbed  the  oxygon  of  the  atmosphere  and 
liberated  an  approximately  equal  volume  of  carbonic  acid. 
He  also  found  that  when  ripe  fruits  were  placed  in  a  con- 
fined atmosphere,  the  oxygen  of  the  atmosphere  was  first 
absorbed,  and  an  equal  volume  of  carbonic  acid  given  out. 
But  the  process  did  not  end  here.  After  the  oxygen  had 
vanished,  carbonic  acid,  in  considerable  quantities,  con- 
tinued to  be  exhaled  by  the  fruits,  which  at  the  same  time 
lost  a  portion  of  their  sugar,  becoming  more  acid  to  the 
taste,  though  the  absolute  quantity  of  acid  was  not 
augmented.  This  was  an  observation  of  capital  importance, 
and  Berard  had  the  sagacity  to  remark  that  the  process 
might  be  regarded  as  a  kind  of  fermentation. 

Thus  the  living  cells  of  fruits  can  absorb  oxygen  and 
breathe  out  carbonic  acid,  exactly  like  the  living  cells  of 
the  leaven  of  beer.  Supposing  the  access  of  oxygen  sud- 
denly cut  off,  will  the  living  fruit  cells  as  suddenly  die,  or 
will  they  continue  to  live  as  yeast  lives,  by  extracting 
oxygen  fron  the  saccharine  juices  round  them?  This  is  a 
question  of  supreme  theoretic  significance.  It  was 
first  answered  affirmatively  by  the  able  and  conclusive 
experiments  of  Lechartier  and  Bellamy,  and  the  answer 
was  subsequently  confirmed  and  explained  by  the  experi- 
ments and  the  reasoning  of  Pasteur.  Berard  only  showed 
the  absorption  of  oxygen  and  the  production  of  carbonic 
acid;  Lechartier  and  Bellamy  proved  the  production  of 
alcohol,  thus  completing  the  evidence  that  it  was  a  case 
of  real  fermentation,  though  the  common  alcoholic  ferment 
was  absent.  So  full  was  Pasteur  of  the  idea  that  the  cells 
of  the  fruit  would  continue  to  live  at  the  expense  of  the 
sugar  of  the  fruit,  that  once  in  his  laboratory,  while  con- 
versing on  these  subjects  with  M.  Dumas,  he  exclaimed, 
"  I  will  wager  that  if  a  grape  be  plunged  into  an  atmos- 
phere of  carbonic  acid,  it  will  produce  alcohol  and  carbonic 
acid  by  the  continued  life  of  its  own  cells — that  they  will 
act  for  a  time  like  the  cells  of  the  true  alcoholic  leaven." 
He  made  the  experiment,  and  found  the  result  to  be  what 
he  had  foreseen.  He  then  extended  the  inquiry.  Plac- 
ing under  a  bell-jar  twenty-four  plums,  he  filled  the  jar 
with  carbonic  acid  gas;  beside  it  he  placed  twenty-four 
similar  plums  uncovered.  At  the  end  of  eight  days  he 
lemoved  the  plums  from  the  jar  and  compared  them  with 


642  FRAGMENTS  OF  8CTKNCK. 

the  others.  The  difference  was  extraordinary.  The  un- 
covered fruits  had  become  soft,  watery,  and  very  sweet; 
the  others  were  firm  and  hard,  their  fleshy  portions  being 
not  at  all  watery.  They  had,  moreover,  lost  a  considerable 
quantity  of  their  sugar.  They  were  afterward  bruised, 
and  the  juice  was  distilled.  It  yielded  six  and  a  half 
grammes  of  alcohol,  or  one  per  cent,  of  the  total  weight 
of  the  plums.  Neither  in  these  plums,  nor  in  the  grape 
first  experimented  on  by  Pasteur,  could  any  trace  of  the 
ordinary  alcoholic  leaven  be  found.  As  previously  proved 
by  Lechartier  and  Belhtmv,  the  fermentation  was  the  work 
of  the  living  cells  of  the  fruit  itself,  after  air  had  been 
denied  to  them.  When,  moreover,  the  cells  were  destroyed 
by  bruising,  no  fermentation  ensued.  The  fermentation 
was  the  correlative  of  a  vital  act,  and  it  ceased  when  life 
was  extinguished. 

Liidersdorf  was  the  first  to  show  by  this  method  that 
yeast  acted,  not,  as  Liebig  had  assumed,  in  virtue  of  its 
organic,  but  in  virtue  of  its  organized  character.  He 
destroyed  the  cells  of  yeast  by  rubbing  them  on  a  ground 
glass  plate,  and  found  that  with  the  destruction  of  the 
organism,  though  its  chemical  constituents  remained,  the 
power  to  act  as  a  ferment  totally  disappeared. 

One  word  more  in  reference  to  Liebig  may  find  a  place 
here.  To  the  philosophic  chemist  thoughtfully  pondering 
these  phenomena,  familiar  with  the  conception  of  molecular 
motion,  and  the  changes  produced  by  the  interactions  of 
purely  chemical  forces,  nothing  could  be  more  natural 
than  to  see  in  the  process  of  fermentation  a  simple  illus- 
tration of  molecular  instability,  the  ferment  propagating 
to  surrounding  molecular  groups  the  overthrow  of  its  own 
tottering  combinations.  Broadly  considered,  indeed,  there 
is  a  certain  amount  of  truth  in  this  theory;  but  Liebig, 
who  propounded  it,  missed  the  very  kernel  of  the  phe- 
omena  when  he  overlooked  or  contemned  the  part  played 
in  fermentation  by  microscopic  life.  He  looked  at  the 
matter  too  little  with  the  eye  of  the  body,  and  too  much 
with  the  spiritual  eye.  He  practically  neglected  the 
microscope,  and  was  unmoved  by  the  knowledge  which  its 
revelations  would  have  poured  in  upon  his  mind.  His 
hypothesis,  as  I  have  said,  was  natural — nay  it  was  a  strik- 
ing illustration  of  Liebig's  power  to  penetrate  and  unveil 
molecular  actions;  but  it  was  an  error,  and  as  such  has 


FERMENTATION.  543 

proved  an  ignis  fatuus  instead  of  &  pharos  to  some  of  his 
followers. 

I  have  said  that  our  air  is  full  of  the  germs  of  ferments 
differing  from  the  alcoholic  leaven,  and  sometimes  seriously 
interfering  with  the  latter.  They  are  the  weeds  of  this 
microscopic  garden  which  often  overshadow  and  choke  the 
flowers.  Let  us  take  an  illustrative  case.  Expose  milk  to 
the  air.  It  will,  after  a  time,  turn  sour,  separating  like 
hlood  into  clot  and  serum.  Place  a  drop  of  this  sour  milk 
under  a  powerful  microscope  and  watch  it  closely.  You 
see  the  minute  butter-globules  animated  by  that  curious 
quivering  motion  called  the  Brownian  motion.  But  let 
not  this  attract  your  attention  too  much,  for  it  is  another 
motion  that  we  have  now  to  seek.  Here  and  there  vou  observe 
a  greater  disturbance  than  ordinary  among  the  globules; 
keep  your  eye  upon  the  place  of  tumult,  and  you  will 
probably  see  emerging  from  it  a  long  eel-like  organism, 
tossing  the  globules  aside  and  wriggling  more  or  less 
rapidly  across  the  field  of  the  microscope.  Familiar  with 
one  sample  of  this  organism,  which  from  its  motions  receives 
the  name  of  vibrio,  you  soon  detect  numbers  of  them.  It 
is  these  organisms,  and  other  analogous  though  apparently 
motionless  ones,  which  by  decomposing  the  milk  render  it 
sour  and  putrid.  They  are  the  lactic  and  putrid  ferments, 
as  the  yeast-plant  is  the  alcoholic  ferment  of  sugar.  Keep 
them  and  their  germs  out  of  your  milk  and  it  will  continue 
sweet.  But  milk  may  become  putrid  without  becoming 
sour.  Examine  such  putrid  milk  microscopically,  and  you 
find  it  swarming  with  shorter  organisms,  sometimes  asso- 
ciated with  the  vibrios,  sometimes  alone,  and  often  mani- 
festing a  wonderful  alacrity  of  motion.  Keep  these 
organisms  and  their  germs  out  of  your  milk  and  it  will 
never  putrefy.  Expose  a  mutton-chop  to  the  air  and  keep 
it  moist;  in  summer  weather  it  soon  stinks.  Place  a  drop 
of  the  juice  of  the  fetid  chop  under  a  powerful  microscope; 
it  is  seen  swarming  with  organisms  resembling  those  in 
the  putrid  milk.  These  organisms,  which  receive  the 
common  name  of  bacteria,*  are  the  agents  of  all  putre- 
faction. Keep  them  and  their  germs  from  your  meat  and 

*  Doubtless  organisms  exhibiting  grave  specific  differences  are 
grouped  together  under  this  common  name. 


544  FRAGMENTS  OF  SCIENCE. 

it  will  remain  forever  sweet.  Thus  we  begin  to  see  that 
within  the  world -of  life  to  which  we  ourselves  belong, 
there  is  another  living  world  requiring  the  microscope  for 
its  discernment,  but  which,  nevertheless,  has  the  most 
important  bearing  on  the  welfare  of  the  higher  life- 
world. 

And  now  let  us  reason  together  as  regards  the  origin  of 
these  bacteria.  A  granular  powder  is  placed  in  your  hands, 
and  you  are  asked  to  state  what  it  is.  You  examine  it.  and 
have,  or  have  not,  reason  to  suspect  that  seeds  of  some 
kind  are  mixed  up  in  it.  To  determine  this  point  you 
prepare  a  bed  in  your  garden,  sow  in  it  the  powder,  and 
soon  after  find  a  mixed  crop  of  docks  and  thistles  sprout- 
ing from  your  bed.  Until  this  powder  was  sown  neither 
docks  nor  thistles  ever  made  their  appearance  in  your 
garden.  You  repeat  the  experiment  once,  twice,  ten  times, 
fifty  times.  From  fifty  different  beds  after  the  sowing  of 
the  powder,  you  obtain  the  same  crop.  What  will  be  your 
response  to  the  question  proposed  to  you?  "  I  am  not  in 
a  condition,"  you  would  say,  "  to  affirm  that  every  grain 
of  the  powder  is  a  dock-seed,  or  a  thistle-seed;  but  I  am  in 
a  condition  to  affirm  that  both  dock  and  thistle-seeds  form, 
at  all  events,  part  of  the  powder. "  Supposing  a  succession 
of  such  powders  to  be  placed  in  your  hands  with  grains 
becoming  gradually  smaller,  until  they  dwindle  to  the  size 
of  impalpable  dust  particles;  assuming  that  you  treat  them 
all  in  the  same  way,  and  that  from  every  one  of  them  in  a 
few  days  you  obtain  a  definite  crop — it  may  be  clover,  it 
may  be  mustard,  it  may  be  mignonette,  it  may  be  a  plant 
more  minute  than  any  of  these,  the  smallness  of  the  par- 
ticles, or  of  the  plants  that  spring  from  them,  does  not 
affect  the  validity  of  the  conclusion.  Without  a  shadow 
of  misgiving  you  would  conclude  that  the  powder  must 
have  contained  the  seeds  or  germs  of  the  life  observed. 
There  is  not  in  the  range  of  physical  science  an  experi- 
ment more  conclusive  nor  an  inference  safer  than  this  one. 

Supposing  the  powder  to  be  light  enough  to  float  in  the 
air,  and  that  you  are  enabled  to  see  it  there  just  as  plainly 
as  you  saw  the  heavier  powder  in  the  palm  of  your  hand. 
If  the  dust  sown  by  the  air  instead  of  by  the  hand 
produce  a  definite  living  crop,  with  the  same  logical 
rigor  you  would  conclude  that  the  germs  of  this  crop 
must  be  mixed  with  the  dust.  To  take  an  illustration: 


FERMENT  A  TION.  54  5 

the  spores  of  the  little  plant  PenicAllium  glaucum,  to 
which  I  have  already  referred,  are  light  enough  to  float 
in  the  air.  A  cut  apple,  a  pear,  a  tomato,  a  slice  of  vege- 
table marrow,  or,  as  already  mentioned,  an  old  moist  boot, 
a  dish  of  paste,  or  a  pot  of  jam,  constitutes  a  proper  soil 
for  the  Penicillium,  Now,  if  it  could  be  proved  that  the 
dust  of  the  air  when  sown  in  this  soil  produces  this  plant, 
while,  wanting  the  dust,  neither  the  air,  nor  the  soil,  nor 
both  together  can  produce  it,  it  would  be  obviously  just 
as  certain  in  this  case  that  the  floating  dust  contains  the 
germs  of  Penicillium  as  that  the  powders  sown  in  your 
garden  contained  the  germs  of  the  plants  which  sprung 
from  them. 

But  how  is  the  floating  dust  to  be  rendered  visible?  In 
this  way.  Build  a  little  chamber  and  provide  it  with  a 
door,  windows,  and  window-shutters.  Let  an  aperture  be 
made  ill  one  of  the  shutters  through  which  a  sunbeam  can 
pass.  Close  the  door  and  windows  so  that  no  light  shall 
enter  save  through  the  hole  in  the  shutter.  The  track  of 
the  sunbeam  is  at  first  perfectly  plain  and  vivid  in  the 
air  of  the  room.  If  all  disturbance  of  the  air  of  the 
chamber  be  avoided,  the  luminous  track  will  become 
fainter  and  fainter,  until  at  last  it  disappears  absolutely, 
and  no  trace  of  the  beam  is  to  be  seen.  What  rendered  the 
beam  visible  at  first?  The  floating  dust  of  the  air,  which, 
thus  illuminated  and  observed,  is  as  palpable  to  sense  as 
dust  or  powder  placed  on  the  palm  of  the  hand.  In  the 
still  air  the  dust  gradually  sinks  to  the  floor  or  sticks  to 
the  walls  and  ceiling,  until  finally,  by  this  self-cleansing 
process,  the  air  is  entirely  freed  from  mechanically  sus- 
pended matter. 

Thus  far,  I  think,  we  have  made  our  footing  sure.  Let 
us  proceed.  Chop  up  a  beefsteak  and  allow  it  to  remain 
for  two  or  three  hours  just  covered  with  warm  water;  you 
thus  extract  the  juice  of  the  beef  in  a  concentrated  form. 
By  properly  boiling  the  liquid  and  filtering  it,  you  can 
obtain  from  it  a  perfectly  transparent  beef-tea.  Expose  a 
number  of  vessels  containing  this  tea  to  the  moteless  air  of 
your  chamber;  and  expose  a  number  of  vessels  containing 
precisely  the  same  liquid  to  the  dust-laden  air.  In  three 
days  every  one  of  the  latter  stinks,  and  examined  with  the 
microscope  every  one  of  them  is  found  swarming  with  the 
bacteria  of  putrefaction.  After  three  mouths,  or  three 


546  FRAGMENTS  OF  SCIENCE. 

years,  the  beef-tea  within  the  chamber  is  found  in  every 
case  as  sweet  and  clear,  and  as  free  from  bacteria,  as  it  was 
at  the  moment  when  it  was  first  put  in.  There  is  abso- 
lutely no  difference  between  the  air  within  and  that  with- 
out save  that  the  one  is  dustless  and  the  other  dust-laden. 
Clinch  the  experiment  thus:  Open  the  door  of  your  cham- 
ber and  allow  the  dust  to  enter  it.  In  three  days  after- 
ward you  have  every  vessel  within  the  chamber  swarming 
with  bacteria,  and  in  a  state  of  active  putrefaction.  Here, 
also,  the  inference  is  quite  as  certain  as  in  the  case  of  the 
powder  sown  in  your  garden.  Multiply  your  proofs  by 
building  fifty  chambers  instead  of  one,  and  by  employing 
every  imaginable  infusion  of  wild  animals  and  tame;  of 
flesh,  fish,  fowl,  and  viscera;  of  vegetables  of  the  most 
various  kinds.  If  in  all  these  cases  you  find  the  dust 
infallibly  producing  its  crop  of  bacteria,  while  neither  the 
dustless  air  nor  the  nutritive  infusion,  nor  both  together, 
are  ever  able  to  produce  this  crop,  your  conclusion  is 
simply  irresistible  that  the  dust  of  the  air  contains  the 
germs  of  the  crop  which  has  appeared  in  your  infusions.  I 
repeat  there  is  no  inference  of  experimental  science  more 
certain  than  this  one.  In  the  presence  of  such  facts,  to 
use  the  words  of  a  paper  lately  published  in  the  "  Philoso- 
phical Transactions/'  it  would  be  simply  monstrous  to 
affirm  that  these  swarming  crops  of  bacteria  are  sponta- 
neously generated. 

Is  there  then  no  experimental  proof  of  spontaneous 
generation?  I  answer  without  hesitation,  none!  But 
to  doubt  the  experimental  proof-  of  a  fact,  and  to  deny 
its  possibility,  are  two  different  things,  though  some 
writers  confuse  matters  by  making  them  synonymous.  In 
fact,  this  doctrine  of  spontaneous  generation,  in  one  form 
or  another,  falls  in  with  the  theoretic  beliefs  of  some 
of  the  foremost  workers  of  this  age;  but  it  is  exactly 
these  men  who  have  the  penetration  to  see,  and  the  honesty 
to  expose,  the  weakness  of  the  evidence  adduced  in  its 
support. 

And  here  observe  how  these  discoveries  tally  with  the 
common  practices  of  life.  Heat  kills  the  bacteria,  cold 
numbs  them.  When  my  housekeeper  has  pheasants  in 
charge  which  she  wishes  to  keep  sweet,  but  which  threaten 
to  give  way,  she  partially  cooks  the  birds,  kills  the  infant 


FERMENTATION.  547 

bacteria,  and  thus  postpones  the  evil  day.  By  boiling  her 
milk  she  also  extends  its  period  of  sweetness.  Some  weeks 
ago  in  the  Alps  I  made  a  few  experiments  on  the  influence 
of  cold  upon  ants.  Though  the  sun  was  strong,  patches 
of  snow  still  maintained  themselves  on  the  mountain 
slopes.  The  ants  were  found  in  the  warm  grass  and  on 
the  "warm  rocks  adjacent.  Transferred  to  the  snow  the 
rapidity  of  their  paralysis  was  surprising.  In  a  few  seconds 
a  vigorous  ant,  after  a  few  languid  struggles,  would  wholly 
lose  its  power  of  locomotion  and  lie  practically  dead  upon 
the  snow.  Transferred  to  the  warm  rock,  it  would  revive, 
to  be  again  smitten  with  death-like  numbness  when  retrans- 
ferred  to  the  snow.  What  is  true  of  the  ant  is  specially 
true  of  our  bacteria.  Their  active  life  is  suspended  by 
cold,  and  with  it  their  power  of  producing  or  continuing 
putrefaction.  This  is  the  whole  philosophy  of  the  preser- 
vation of  meat  by  cold.  The  fishmonger,  for  example, 
when  he  surrounds  his  very  assailable  wares  by  lumps  of 
ice,  stays  the  process  of  putrefaction  by  reducing  to  numb- 
ness and  inaction  the  organisms  which  produce  it,  and 
in  the  absence  of  which  his  fish  would  remain  sweet  and 
sound.  It  is  the  astonishing  activity  into  which  these 
bacteria  are  pushed  by  warmth  that  renders  a  single  sum- 
mer's day  sometimes  so  disastrous 'to  the  great  butchers  of 
London  .and  Glasgow.  The  bodies  of  guides  lost  in  the 
crevasses  of  Alpine  glaciers  have  come  to  the  surface  forty 
years  after  their  interment,  without  the  flesh  showing  any 
sign  of  putrefaction.  But  the  most  astonishing  case  of 
this  kind  is  that  of  the  hairy  elephant  of  Siberia  which 
was  found  incased  in  ice.  It  had  been  buried  for  ages,  but 
when  laid  bare  its  flesh  was  sweet,  and  for  some  time 
afforded  copious  nutriment  to  the  wild  beasts  which  fed 
upon  it. 

Beer  is  assailable  by  all  the  organisms  here  referred  to, 
some  of  which  produce  acetic,  some  lactic,  and  some 
butyric  acid,  while  yeast  is  open  to  attack  from  the  bacteria 
of  putrefaction.  In  relation  to  the  particular  beverage  the 
brewer  wishes  to  produce,  these  foreign  ferments  have 
been  properly  called  ferments  of  disease.  The  cells  of  the 
true  leaven  are  globules,  usually  somewhat  elongated. 
The  other  organisms  are  more  or  less  rod-like  or  eel-like  in 
shape,  some  of  them  being  beaded  so  as  to  resemble  neck- 
laces. Each  of  these  organisms  produces  a  fermentation 


548  FRAGMENTS  OF  SCIENCE. 

and  a  flavor  peculiar  to  itself.  Keep  them  out  of  your 
beer  and  it  remains  forever  unaltered.  Never  without 
them  will  your  beer  contract  disease.  But  their  germs  are 
in  the  air,  in  the  vessels  employed  in  the  brewery;  even  in 
the  yeast  used  to  impregnate  the  wort.  Consciously  or 
unconsciously,  the  art  of  the  brewer  is  directed  against 
them.  His  aim  is  to  paralyze,  if  he  cannot  annihilate 
them. 

For  beer,  moreover,  the  question  of  temperature  is  one 
of  supreme  importance;  indeed,  the  recognized  influence 
of  temperature  is  causing  on  the  continent  of  Europe  a 
complete  revolution  in  the  manufacture  of  beer.  When  I 
was  a  student  in  Berlin,  in  1851,  there  were  certain  places 
specially  devoted  to  the  sale  of  Bavarian  beer,  which  was 
then  making  its  way  into  public  favor.  This  beer  is  pre- 
pared by  what  is  called  the  process  of  low  fermentation; 
the  name  being  given  partly  because  the  yeast  of  the  beer; 
instead  of  rising  to  the  top  and  issuing  through  the  bung- 
hole,  falls  to  the  bottom  of  the  cask;  but  partly,  also, 
because  it  is  produced  at  a  low  temperature.  The  other 
and  older  process,  called  high  fermentation,  is  far  more 
handy,  expeditious,  and  cheap.  .In  high  fermentation 
eight  days  suffice  for  the  production  of  the  beer;  in  low 
fermentation,  ten,  fifteen,  even  twenty  days  are  found 
necessary.  Vast  quantities  of  ice,  moreover,  are  consumed 
in  the  process  of  low  fermentation.  In  the  single  brewery 
of  Dreher,  of  Vienna,  a  hundred  million  pounds  of  ice  are 
consumed  annually  in  cooling  the  wort  and  beer.  Not- 
withstanding these  obvious  and  weighty  drawbacks,  the 
low  fermentation  is  rapidly  displacing  the  high  upon  the 
Continent.  Here  are  some  statistics  which  show  the 
number  of  breweries  of  both  kinds  existing  in  Bohemia 
in  1860,  1865,  and  1870: 

I860.  1865.          1870. 

High  Fermentation     .     .     281  81  18 

Low  Fermentation      .     .     135          459          831 

Thus  in  ten  years  the  number  of  high-fermentation 
breweries  fell  from  281  to  18,  while  the  number  of  low- 
fermentation  breweries  rose  from  135  to  831.  The  sole 
reason  for  this  vast  change — a  change  which  involves  a 
great  expenditure  of  time,  labor,  and  money — is  the 
additional  command  which  it  gives  the  brewer  over  the 


FEhMENTATION.  549 

fortuitous  ferments  of  disease.  These  ferments,  which,  it 
is  to  be  remembered,  are  living  organisms,  have  their 
activity  suspended  by  temperatures  below  10  degrees  C., 
and  as  long  as  they  are  reduced  to  torpor  the  beer  remains 
untainted  either  by  acidity  or  putrefaction.  The  beer  of 
low  fermentation  is  brewed  in  winter,  and  kept  in  cool 
cellars;  the  brewer  being  thus  enabled  to  dispose  of  it  at 
his  leisure,  instead  of  forcing  its  consumption  to  avoid  the 
loss  involved  in  its  alteration  if  kept  too  long.  Hops,  it 
may  be  remarked,  act  to  some  extent  as  an  antiseptic  to 
beer.  The  essential  oil  of  the  hop  is  bactericidal:  hence 
the  strong  impregnation  with  hop  juice  of  all  beer  intended 
for  exportation. 

These  low  organisms,  which  one  might  be  disposed  to 
regard  as  the  beginnings  of  life,  were  we  not  warned  that 
the  microscope,  precious  and  perfect  as  it  is,  has  no  power 
to  show  us  the  real  beginnings  of  life,  are  by  no  means 
purely  useless  or  purely  mischievous  in  the  economy  of 
nature.  They  are  only  noxious  when  out  of  their  proper 
place.  They  exercise  a  useful  and  valuable  function  as  the 
burners  and  consumers  of  dead  matter,  animal  and  vege- 
table, reducing  such  matter,  with  a  rapidity  otherwise 
unattainable,  to  innocent  carbonic  acid  and  water.  Fur- 
thermore, they  are  not  all  alike,  and  it  is  only  restricted 
classes  of  them  that  are  really  dangerous  to  man.  One 
difference  in  their  habits  is  worthy  of  special  reference 
here.  Air,  or  rather  the  oxygen  of  the  air,  which  is 
absolutely  necessary  to  the  support  of  the  bacteria  of 
putrefaction,  is,  according  to  Pasteur,  absolutely  deadly  to 
the  vibrios  which  provoke  the  butyric  acid  fermentation. 
This  has  been  illustrated  by  the  following  beautiful  obser- 
vation. 

A  drop  of  the  liquid  containing  those  small  organisms  is 
placed  upon  glass,  and  on  the  drop  is  placed  a  circle  of 
exceedingly  thin  glass;  for,  to  magnify  them  sufficiently, 
it  is  necessary  that  the  object-glass  of  the  microscope 
should  come  very  close  to  the  organisms.  Round  the  edge 
of  the  circular  plate  of  glass  the  liquid  is  in  contact  with 
the  air,  and  incessantly  absorbs  it,  including  the  oxygen. 
Here,  if  the  drop  be  charged  with  bacteria,  we  have  a  zone 
of  very  lively  ones.  But  through  this  living  zone,  greedy 
of  oxygen  and  appropriating  it,  the  vivifying  gas  cannot 
penetrate  to  the  center  of  the  film.  In  the  middle,  there- 


550  FRAGMENTS  OF  SCIENCE. 

fore,  the  bacteria  die,  while  their  peripheral  colleagues 
continue  active.  If  a  bubble  of  air  chance  to  be  enclosed 
in  the  film,  round  it  the  bacteria  will  pirouette  and  wabble 
until  its  oxygen  has  been  absorbed,  after  which  all  their 
motions  cease.  Precisely  the  reverse  of  all  this  occurs 
with  the  vibrios  of  the  butyric  acid.  In  their  case  it  is  the 
peripheral  organisms  that  are  first  killed,  the  central  ones 
remaining  vigorous  while  ringed  by  a  zone  of  dead.  Pas- 
teur, moreover,  filled  two  vessels  with  a  liquid  containing 
these  vibrios;  through  one  vessel  he  led  air,  and  killed  its 
vibrios  in  half  an  hour;  through  the  other  he  led  carbonic 
acid,  and  after  three  hours  found  the  vibrios  fully  active. 
It  was  while  observing  these  differences  of  deportment 
fifteen  years  ago  that  the  thought  of  life  without  air,  and 
its  bearing  upon  the  theory  of  fermentation,  flashed  upon 
the  mind  of  this  admirable  investigator. 

"We  now  approach  an. aspect  of  this  question  which  con- 
cerns us  still  more  closely,  and  will  be  best  illustrated  by 
an  actual  fact.  A  few  years  ago  I  was  bathing  in  an 
Alpine  stream,  and  returning  to  my  clothes  from  the  cas- 
cade which  had  been  my  shower-bath,  I  slipped  upon  a 
block  of  granite,  the  sharp  crystals  of  which  stamped 
themselves  into  my  naked  shin.  The  wound  was  an  awk- 
ward one,  but  being  in  vigorous  health  at  the  time,  I  hoped 
for  a  speedy  recovery.  Dipping  a  clean  pocket-handker- 
chief into  the  stream,  I  wrapped  it  round  the  wound, 
limped  home,  and  remained  for  four  or  five  days  quietly  in 
bed.  There  was  no  pain,  and  at  the  end  of  this  time  I 
thought  myself  quite  fit  to  quit  my  room.  The  wound, 
when  uncovered,  was  found  perfectly  clean,  uuinflamed, 
and  entirely  free  from  matter.  Placing  over  it  a  bit  of 
goldbeater's-skin,  I  walked  about  all  day.  Toward  evening 
itching  and  heat  were  felt;  a  large  accumulation  of  matter 
followed,  and  I  was  forced  to  go  to  bed  again.  The  water- 
bandage  was  restored,  but  it  was  powerless  to  check  the 
action  now  set  up;  arnica  was  applied,  but  it  made  matters 
worse.  The  inflammation  increased  alarmingly,  until 
finally  I  had  to  be  carried  on  men's  shoulders  down  the 
mountain  and  transported  to  Geneva,  where,  thanks  to 
the  kindness  of  friends,  I  was  immediately  placed  in  the 
best  medical  hands.  On  the  morning  after  my  arrival  in 
Geneva,  Dr.  Gautier  discovered  an  abscess  in  my  instep,  at 


FOMENTATION.  551 

a  distance  of  five  inches  from  the  wound.  The  two  were 
connected  by  a  channel,  or  sinus,  as  it  is  technically  called, 
through  which  he  was  able  to  empty  the  abscess,  without 
the  application  of  the  lance. 

By  what  agency  was  that  channel  formed — what  was  it 
that  thus  tore  asunder  the  sound  tissue  of  my  instep,  and 
kept  me  for  six  weeks  a  prisoner  in  bed?  *  In  the  very 
room  where  the  water  dressing  had  been  removed  from  my 
wound  and  the  goldbeater's-skin  applied  to  it,  I  opened 
this  year  a  number  of  tubes,  containing  perfectly  clear  and 
sweet  infusions  of  fish,  flesh,  and  vegetable.  These  her- 
metically sealed  infusions  had  been  exposed  for  weeks, 
both  to  the  sun  of  the  Alps  and  to  the  warmth  of  a 
kitchen,  without  showing  the  slightest  turbidity  or  sign 
of  life.  But  two  days  after  they  were  opened  the  greater 
number  of  them  swarmed  with  the  bacteria  of  putrefaction, 
the  germs  of  which  had  been  contracted  from  the  dust-laden 
air  of  the  room.  And  had  the  matter  from  my  abscess 
been  examined,  my  memory  of  its  appearance  leads  me  to 
infer  that  it  would  have  been  found  equally  swarming  with 
these  bacteria — that  it  was  their  germs  which  got  into  my 
incautiously  opened  wound,  and  that  they  were  the  subtile 
workers  that  burrowed  down  my  shin,  dug  the  abscess  in 
my  instep,  and  produced  effects  which  might  easily  have 
proved  fatal. 

This  apparent  digression  brings  us  face  to  face  with  the 
labors  of  a  man  who  combines  the  penetration  of  the  true 
theorist  with  the  skill  and  conscientiousness  of  the  true  ex- 
perimenter, and  whose  practice  is  one  continued  demonstra- 
tion of  the  theory  that  the  putrefaction  of  wounds  is  to  be 
averted  by  the  destruction  of  the  germs  of  bacteria.  Not 
only  from  his  own  reports  of  his  cases,  but  from  the 
reports  of  eminent  men  who  have  visited  his  hospital, 
and  from  the  opinions  expressed  to  me  by  continental 
surgeons,  do  I  gather  that  one  of  the  greatest  steps  ever 
made  in  the  art  of  surgery  was  the  introduction  of  the 
antiseptic  system  of  treatment,  introduced  by  Professor 
Lister. 

The  interest  of  this  subject  does  not  slacken  as  we 
proceed.  We  began  with  the  cherry-cask  and  beer-vat; 
we  end  with  the  body  of  man.  There  are  persons  born 
with  the  power  of  interpreting  natural  facts,  as  there 


552  FRAGMENTS  OF  SCIENCE. 

are  others  smitten  with  everlasting  incompetence  in  regard 
to  such  interpretation.  To  the  former  class  in  an  eminent 
degree  belonged  the  illustrious  philosopher  Robert  Boyle, 
whose  words  in  relation  to  this  subject  have  in  them 'the 
forecast  of  prophecy.  "And  let  me  add,"  writes  Boyle  in 
his  "Essay  on  the  Pathological  Part  of  Physik,"  "  that  he 
that  thoroughly  understands  the  nature  of  ferments  and 
fermentations  shall  probably  be  much  better  able  than  he 
that  ignores  them,  to  give  a  fair  account  of  divers  phe- 
nomena of  several  diseases  (as  well  fevers  as  others),  which 
will  perhaps  be  never  properly  understood  without  an 
of  ferine 


insight  into  the  doctrine  of  fermentations." 

Two  hundred  years  have  passed  since  these  pregnant 
words  were  written,  arid  it  is  only  in  this  our  day  that  men 
are  beginning  to  fully  realize  their  truth.  In  the  domain 
of  surgery  the  justice  of  Boyle's  surmise  has  bean  most 
strictly  demonstrated.  But  we  now  pass  the  bounds  of 
surgery  proper,  and  enter  the  domain  of  epidemic  disease, 
including  those  fevers  so  sagaciously  referred  to  by  Boyle. 
The  most  striking  analogy  between  ncontagium  and  a 
ferment  is  to  be  found  in  the  power  of  indefinite  self- 
multiplication  possessed  and  exercised  by  both.  You 
know  the  exquisitely  truthful  figures  regarding  leaven  em- 
ployed in  the  New  Testament.  A  particle  hid  in  three 
measures  of  meal  leavens  it  all.  A  little  leaven  leaveneth 
the  whole  lump.  In  a  similar  manner,  a  particle  of 
contagium  spreads  through  the  human  body  and  may  be  so 
multiplied  as  to  strike  down  whole  populations.  Consider 
the  effect  produced  upon  the  system  by  a  microscopic 
quantity  of  the  virus  of  small-pox.  That  virus  is,  to  all 
intents  and  purposes,  a  seed.  It  is  sown  as  yeast  is  sown, 
it  grows  and  multiplies  as  yeast  grows  and  multiplies,  and 
it  always  reproduces  itselL  To  Pasteur  we  are  indebted 
for  a  series  of  masterly  researches,  wherein  he  exposes  the 
looseness  and  general  baselessness  of  prevalent  notions 
regarding  the  transmutation  of  one  ferment  into  another. 
He  guards  himself  against  saying  it  is  impossible.  The 
true  investigator  is  sparing  in  the  use  of  this  word,  though 
the  use  of  it  is  unsparingly, ascribed  to  him;  but,  as  a 
matter  of  fact,  Pasteur  has  never  been  able  to  effect  the 
alleged  transmutation,  while  he  has  been  always  able  to 
point  out  the  open  doorways  through  which  the  aftirmers 


FERMENTATION.  553 

of  such  transmutations  had  allowed  error  to  march  in  upon 
them.* 

The  great  source  of  error  here  has  been  already  alluded 
to  in  this  discourse.  The  observers  worked  in  an  atmos- 
phere charged  with  the  germs  of  different  organisms;  the 
mere  accident  of  first  possession  rendering  now  one 
organism,  now  another,  triumphant.  In  different  stages, 
moreover,  of  its  fermentative  or  putrefactive  changes, 
the  same  infusion  may  so  alter  as  to  be  successively  taken 
possession  of  by  different  organisms.  Such  cases  have 
been  adduced  to  show  that  the  earlier  organisms  must 
have  been  transformed  into  the  later  ones,  whereas  they 
are  simply  cases  in  which  different  germs,  because  of 
changes  in  the  infusion,  render  themselves  valid  at  different 
times. 

By  teaching  us  how  to  cultivate  each  ferment  in  its 
purity — in  other  words,  by  teaching  us  how  to  rear  the 
individual  organism  apart  from  all  others — Pasteur  has 
enabled  us  to  avoid  all  these  errors.  And  where  this  isola- 
tion of  a  particular  organism  has  been  duly  effected  it 
grows  and  multiplies  indefinitely,  but  no  change  of  it  into 
another  organism  is  ever  observed.  In  Pasteur's  researches 
the  Bacterium  remained  a  Bacterium,  the  Vibrio  a  Vibrio, 
the  Penicilliurn  a  Penicillin rn,  and  the  Torula  a  Torula. 
Sow  any  of  these  in  a  state  of  purity  in  an  appropriate 
liquid;  you  get  it,  and  it  alone,  in  the  subsequent  crop. 
In  like  manner,  sow  small-pox  in  the  human  body,  your 
crop  is  srnall-pox.  Sow  there  scarlatina,  and  your  crop  is 
scarlatina.  Sow  typhoid  virus,  your  crop  is  typhoid — 
cholera,  your  crop  is  cholera.  The  disease  bears  as  con- 
stant a  relation  to  its  contagium  as  the  microscopic  organ- 
isms just  enumerated  do  to  their  germs,  or  indeed  as  a 
thistle  does  to  its  seed.  No  wonder  then,  with  analogies 
so  obvious  and  so  striking,  that  the  conviction  is  spreading 
and  growing  daily  in  strength,  that  reproductive  parasitic 
life  is  at  the  root  of  epidemic  disease — that  living  ferments 
finding  lodgment  in  the  body  increase  there  and  multiply, 
directly  ruining  the  tissue  on  which  they  subsist,  or  de- 

*  Those  who  wish  for  an  illustration  of  the  care  necessary  in  these 
researches,  and  of  the  carelessness  with  which  they  have  in  some 
cases  been  conducted,  will  do  well  to  consult  the  Rev.  W.  H.  Dallin- 
ger's  excellent  "  Notes  on  Heterogenesis  "  in  the  October  number  of 
the  Popular  Science  Review. 


554  1?RAGMENTS  OF  SCIENCE. 

stroyiug  life  indirectly  by  the  generation  of  poisonous  com- 
pounds within  the  body.  This  conclusion,  which  comes  to 
us  with  a  presumption  almost  amounting  to  demonstration, 
is  clinched  by  the  fact  that  virulently  infective  diseases 
have  been  discovered  with  which  living  organisms  are  as 
closely  and  as  indissolably  associated  as  the  growth  of 
Torn  la  is  with  the  fermentation  of  beer. 

And  here,  if  you  will  permit  me,  I  would  utter  a  word 
of  warning  to  well-meaning  people.  We  have  now  reached 
a  phase  of  this  question  when  it  is  of  the  very  last  impor- 
tance that  light  should  once  for  all  be  thrown  upon  the 
manner  in  which  contagious  and  infectious  diseases  take 
root  and  spread.  To  this  end  the  action  of  various  fer- 
ments upon  the  organs  and  tissues  of  the  living  body  must 
be  studied;  the  habitat  of  each  special  organism  concerned 
in  the  production  of  each  specific  disease  must  be  deter- 
mined, and  the  mode  bv  which  its  germs  are  spread  abroad 
as  sources  of  further  infection.  It  is  only  by  such  rigidly 
accurate  inquiries  that  we  can  obtain  final  and  complete 
mastery  over  these  destroyers.  Hence,  while  abhorring 
cruelty  of  all  kinds,  while  shrinking  sympathetically  from  all 
animal  suffering — suffering  which  my  own  pursuits  never 
call  upon  me  to  inflict — an  unbiased  survey  of  the  field 
of  research  now  opening  out  before  the  physiologist  causes 
me  to  conclude,  that  no  greater  calamity  could  befall  the 
human  race  than  the  stoppage  of  experimental  inquiry  in 
this  direction.  A  lady  whose  philanthropy  has  rendered 
her  illustriobis  said  to  me  some  time  ago,  that  science  was 
becoming  immoral;  that  the  researches  of  the  past,  unlike 
those  of  the  present,  were  carried  on  without  cruelty.  I 
replied  to  her  that  the  science  of  Kepler  and  Newton,  to 
which  she  referred,  dealt  with  the  laws  and  phenomena  of 
inorganic  nature;  but  that  one  great  advance  made  by 
modern  science  was  in  the  direction  of  biology,  or  the 
science  of  life;  and  that  in  this  new  direction  scientific 
inquiry,  though  at  the  outset  pursued  at  the  cost  of  some 
temporary  suffering,  would  in  the  end  prove  a  thousand 
times  more  beneficent  than  it  had  ever  hitherto  been.  I 
said  this  because  I  saw  th:ft  the  very  researches  which  the 
lady  deprecated  were  leading  us  to  such  a  knowledge  of 
epidemic  diseases  as  will  enable  us  finally  to  sweep  these 
scourges  of  the  human  race  from  the  face  of  the  earth. 

This  is  a  point  of  such  capital  importance  that  I  should 


FERMENTATION.  556 

like  to  bring  it  home  to  your  intelligence  by  a  single  trust- 
worthy illustration.  In  1850,  two  distinguished  French 
observers,  MM.  Davainne  and  Bayer,  noticed  in  the  blood 
of  animals  which  had  died  of  the  virulent  disease  called 
splenic  fever,  small  microscopic  organisms  resembling 
transparent  rods,  but  neither  of  them  at  that  time  attached 
any  significance  to  the  observation.  In  1861,  Pasteur 
published  a  memoir  on  the  fermentation  of  butyric  acid, 
wherein  he  described  the  organism  which  provoked  it;  and 
after  reading  this  memoir  it  occurred  to  Davainne  that 
splenic  fever  might  be  a  case  of  fermentation  set  up  within 
the  animal  body,  by  the  organisms  which  had  been  observed 
by  him  and  Raver.  This  idea  has  been  placed  beyond  all 
doubt  by  subsequent  research. 

Observations  of  the  highest  importance  have  also  been 
made  on  splenic  fever  by  Pollender  and  Brauell.  Two 
years  ago,  Dr.  Burden  Sanderson  gave  us  a  very  clear 
account  of  what  was  known  up  to  that  time  of  this  dis- 
order. With  regard  to  the  permanence  of  the  coutagium, 
it  had  been  proved  to  hang  for  years  about  localities  where 
it  had  once  prevailed;  and  this  seemed  to  show  that  the 
rod-like  organisms  could  not  constitute  the  contagium, 
because  their  infective  power  was  found  to  vanish  in  a  few 
weeks.  But  other  facts  established  an  intimate  connection 
between  the  organisms  and  the  disease,  so  that  a  review  of 
all  the  facts  caused  Dr.  Sanderson  to  conclude  that  the 
contagium  existed  in  two  distinct  forms:  the  one  "  fugitive  " 
and  visible  as  transparent  rods;  the  other  permanent  but 
"  latent,"  and  not  yet  brought  within  the  grasp  of  the 
microscope. 

At  the  time  that  Dr.  Sanderson  was  writing  this  report, 
a  young  German  physician,  named  Koch,*  occupied  with 
the  duties  of  his  profession  in  an  obscure  country  district, 
was  already  at  work,  applying,  during  his  spare  time, 
various  original  and  ingenious  devices  to  the  inrestigation 
of  splenic  fever.  He  studied  the  habits  of  the  rod-like 
organisms,  and  found  the  aqueous  humor  of  an  ox's  eye  to 
be  particularly  suitable  for  their  nutrition.  With  a  drop 
of  the  aqueous  humor  he  mixed  the  tiniest  speck  of  a 
liquid  containing  the  rods,  placed  the  drop  under  his 

*  This,  I  believe,  was  the  first  reference  to  the  researches  of  Koch 
made  in  this  country.  1879. 


556  FRAGMENTS  OP  RCtENCti. 

microscope,  warmed  it  suitably,  and  observed  the  subse- 
quent action.  During  the  first  two  hours  hardly  any 
change  was  noticeable;  but  at  the  end  of  this  time  the  rods 
began  to  lengthen,  and  the  action  was  so  rapid  that  at  the 
end  of  three  or  four  hours  they  attained  from  ten  to  twenty 
times  their  original  length.  At  the  end  of  a  few  additional 
hours  they  had  formed  filaments  in  many  cases  a  hundred 
times  the  length  of  the  original  rods.  The  same  filament, 
in  fact,  was  frequently  observed  to  stretch  through  several 
fields  of  the  microscope.  Sometimes  they  lay  in  straight 
lines  parallel  to  each  other,  in  other  cases  they  were  bent, 
twisted,  and  coiled  into  the  most  graceful  figures;  while 
sometimes  they  formed  knots  of  such  bewildering  com- 
plexity that  it  was  impossible  for  the  eye  to  trace  the 
individual  filaments  through  the  confusion. 

Had  the  observation  ended  here  an  interesting  scientific 
fact  would  have  been  added  to  our  previous  store,  but  the 
addition  would  have  been  of  little  practical  value.  Koch, 
however,  continued  to  watch  the  filaments,  and  after  a 
time  noticed  little  dots  appearing  within  them.  .  These 
dots  became  more  and  more  distinct,  until  finally  the 
whole  length  of  the  organism  was  studded  with  minute 
ovoid  bodies,  which  lay  within  the  outer  integument  like 
peas  within  their  shell.  By  and  by  the  integument  fell  to 
pieces,  the  place  of  the  organisms  being  taken  by  a  long 
row  of  seeds  or  spores.  These  observations,  which  were 
confirmed  in  all  respects  by  the  celebrated  naturalist,  Colm 
of  Breslau,  are  of  the  highest  importance.  They  clear  up 
the  existing  perplexity  regarding  the  latent  and  visible 
contagia  of  splenic  fever;  for  in  the  most  conclusive 
manner  Koch  proved  the  spores,  as  distinguished  from 
the  rods,  to  constitute  the  contagium  of  the  fever  in  its 
most  deadly  and  persistent  form. 

How  did  he  reach  this  important  result?  Mark  the 
answer.  There  was  but  one  way  open  to  him  to  test  the 
activity  of  the  contagium,  and  that~  was  the  inoculation 
with  it  of  living  animals.  He  operated  upon  guinea-pigs 
and  rabbits,  but  the  vast  majority  of  his  experiments  were 
made  upon  mice.  Inoculating  them  with  the  fresh  blood 
of  an  animal  suffering  from  splenic  fever,  they  invariably 
died  of  the  same  disease  within  twenty  or  thirty  hours 
after  inoculation.  He  then  sought  to  determine  how  the 
contagium  maintained  its  vitality.  Drying  the  infectious 


FERMKN'IATION.  557 

blood  containing  the  rod-like  organisms,  in  which,  however, 
the  spores  were  not  developed,  he  found  the  contagium  to 
be  that  which  Dr.  Sanderson  calls  "  fugitive/'  It  main- 
tained its  power  of  infection  for  five  weeks  at  the  furthest. 
He  then  dried  blood  containing  the  fully-developed  spores, 
and  exposed  the  substance  to  a  variety  of  conditions.  He 
permitted  the  dried  blood  to  assume  the  form  of  dust; 
wetted  this  dust,  allowed  it  to  dry  again,  permitted  it  to 
remain  for  an  indefinite  time  in  the  midst  of  putrefying 
matter,  and  subjected  it  to  various  other  tests.  After  keeping 
the  spore-charged  blood  which  had  been  treated  in  this 
fashion  for  four  years,  he  inoculated  a  number  of  mice 
with  it,  and  found  its  action  as  fatal  as  that  of  blood 
fresh  from  the  veins  of  an  animal  suffering  from  splenic 
fever.  There  was  no  single  escape  from  death  after 
inoculation  by  this  deadly  contagium.  Uncounted  millions 
of  these  spores  are  developed  in  the  body  of  every  animal 
which  has  died  of  splenic  fever,  and  every  spore  of  these 
millions  is  competent  to  produce  the  disease.  The  name 
of  this  formidable  parasite  is  Bacillus  anthracis.* 

Now  the  very  first  step  toward  the  extirpation  of  these 
contagia  is  the  knowledge  of  their  nature;  and  the  knowl- 
edge brought  to  us  by  Dr.  Koch  will  render  as  certain  the 
stamping  out  of  splenic  fever  as  the  stoppage  of  the  plague 
of  pebr.ine  by  the  researches  of  Pasteur,  f  One  small  item 
of  statistics  will  show  what  this  implies.  In  the  single 
district  of  Novgorod  in  Russia,  between  the  years  1867  and 
1870,  over  fifty-six  thousand  cases  of  death  by  splenic 

*  Koch  found  that  to  produce  its  characteristic  effects  the  contagium 
of  the  splenic  fever  must  enter  the  blood;  the  virulently  infective 
spleen  of  a  diseased  animal  may  be  eaten  with  impunity  by  mice. 
On  the  other  hand,  the  disease  refuses  to  be  communicated  by  inocu 
lation  to  dogs,  partridges,  or  sparrows.  In  their  blood  Bacillus 
ti/it/intcis  ceases  to  act  as  a  ferment.  Pasteur  announced  more  than 
six  years  ago  the  propagation  of  the  vibrios  of  the  silk-worm  disease 
called  flacherie,  both  by  fission  and  by  spores.  He  also  made  some 
remarkable  experiments  on  the  permanence  of  the  contagium  in  the 
form  of  spores.  See  "  Etudes  sur  la  Maladie  des  Vers  a  Soie,"  pp. 
168  and  256. 

f  Surmising  that  the  immunity  enjoyed  by  birds  might  arise  from 
the  heat  of  their  blood,  which  destroyed  the  bacillus,  Pasteur 
lowered  their  temperature  artificially,  inoculated  them,  and  killed 
them.  He  also  raised  the  temperature  of  guinea-pigs  after  inoculation, 
and  saved  them.  It  is  needless  to  dwell  for  a  moment  on  the  impor- 
tance of  this  experiment. 


558  FRAGMENTS  OF  SCIENCE. 

fever,  among  horses,  cows,  and  sheep  were  recorded.  Nor 
did  its  ravages  confine  themselves  to  the  animal  world,  for 
during  the  time  and  in  the  district  referred  to,  five  hundred 
and  twenty-eight  hu'rnan  beings  perished  in  the  agonies  of 
the  same  disease. 

A  description  of  the  fever  will  help  you  to  come  to  a 
right  decision  on  the  point  which  I  wish  to  submit  to  your 
consideration.  "  An  animal,"  says  Dr.  Burdon  Sanderson, 
"  which  perhaps  for  the  previous  day  has  declined  food, 
and  shown  signs  of  general  disturbance,  begins  to  shudder 
and  to  have  twitches  of  the  muscles  of  the  back,  and  soon 
after  becomes  weak  and  listless.  In  the  meantime  the 
respiration  becomes  frequent  and  often  difficult,  and  the 
temperature  rises  three  or  four  degrees  above  the  normal; 
but  soon  convulsions,  affecting  chiefly  the  muscles  of  the 
back  and  loins,  usher  in  the  final  collapse  of  which  the 
progress  is  marked  by  the  loss  of  all  power  of  moving  the 
trunk  or  extremities,  diminution  of  temperature,  mucous 
and  sanguinolent  alvine  evacuations,  and  similar  discharges 
from  the  mouth  and  nose."  In  a  single  district  of  Kussia, 
as  above  remarked,  fifty-six  thousand  horses,  cows,  and 
sheep,  and  five  hundred  and  twenty-eight  men  and  women, 
perished  in  this  way  during  a  period  of  two  or  three  years. 
What  the  annual  fatality  is  throughout  Europe  I  have  no 
means  of  knowing.  Doubtless  it  must  be  very  great. 
The  question,  then,  which  I  wish  to  submit  to  your  judg- 
ment is  this:  Is  the  knowledge  which  reveals  to  us  the 
nature,  and  which  assures  the  extirpation,  of  a  disorder  so 
virulent  and  so  vile,  worth  the  price  paid  for  it?  It  is 
exceedingly  important  that  assemblies  like  the  present 
should  see  clearly  the  issues  at  stake  in  such  questions  as 
this,  and  that  the  properly  informed  sense  of  the  commu- 
nity should  temper,  if  not  restrain,  the  rashness  of  those 
who,  meaning  to  be  tender,  become  agents  of  cruelty  by 
the  imposition  of  short-sighted  restrictions  upon  physio- 
logical investigations.  It  is  a  modern  instance  of  zeal  for 
God,  but  not  according  to  knowledge,  the  excesses  of 
which  must  be  corrected  by  an  instructed  public  opinion. 

And  now  let  us  cast  a  backward  glance  on  the  field  we 
have  traversed,  and  try  to  extract  from  our  labors  such 
further  profit  as  they  can  yield.  For  more  than  two 
thousand  years  the  attraction  of  light  bodies  by  amber  was 


FERMENTATION.  559 

the  sum  of  human  knowledge  regarding  electricity,  and 
for  more  than  two  thousand  years  fermentation  was  effected 
without  any  knowledge  of  its  cause.  In  science  one  dis- 
covery grows  out  of  another,  and  cannot  appear  without^ 
its  proper  antecedent.  Thus,  before  fermentation  could* 
be  understood,  the  microscope  had  to  be  invented,  and 
brought  to  a  considerable  degree  of  perfection.  Note  the 
growth  of  knowledge.  Leeuwenhoek,  in  1680,  found  yeast 
to  be  a  mass  of  floating  globules,  but  he  had  no  notion 
that  the  globules  were  alive.  This  was  proved  in  1835  by 
Cagniard  de  la  Tour  and  Schwann.  Then  came  the  ques- 
tion as  to  the  origin  of  such  microscopic  organisms,  and  in 
this  connection  the  memoir  of  Pasteur,  published  in  the 
"  Annales  de  Chimie"  for  1863,  is  the  inauguration  of  a 
new  epoch. 

On  that  investigation  all  Pasteur's  subsequent  labors 
were  based.  Ravages  had  over  and  over  again  occurred 
among  French  wines.  There  was  no  guarantee  that  they 
would  not  become  acid  or  bitter,  particularly  when 
exported.  The  commerce  in  wines  was  thus  restricted, 
and  disastrous  losses  were  often  inflicted  on  the  wine- 
grower. Every  one  of  these  diseases  was  traced  to  the  life 
of  an  organism.  Pasteur  ascertained  the  temperature 
which  killed  these  ferments  of  disease,  proving  it  to  be  so 
low  as  to  be  perfectly  harmless  to  the  wine.  By  the  simple 
expedient  of  heating  the  wine  to  a  temperature  of  fifty 
degrees  Centigrade,  he  rendered  it  inalterable,  and  thus 
saved  his  country  the  loss  of  millions.  He  then  went  on 
to  vinegar — vinaigre,  acid  wine — which  he  proved  to  be 
produced  by  a  fermentation  set  up  by  a  little  fungus  called 
Mycoderma  aceti.  Torula,  in  fact,  converts  the  grape 
juice  into  alcohol,  and  Mycoderma  aceti  converts  the 
alcohol  into  vinegar.  Here  also  frequent  failures  occurred, 
and  severe  losses  were  sustained.  Through  the  operation 
of  unknown  causes,  the  vinegar  often  became  unfit  for  use, 
sometimes  indeed  falling  into  utter  putridity.  It  had  been 
long  known  that  mere  exposure  to  the  air  was  sufficient  to 
destroy  it.  Pasteur  studied  all  these  changes,  traced  them 
to  their  living  causes,  and  showed  that  the  permanent 
health  of  the  vinegar  was  ensured  by  the  destruction  of 
this  life.  He  passed  from  the  diseases  of  vinegar  to  the 
study  of  a  malady  which  a  dozen  years  ago  had  all  but 
ruiued  the  silk  husbandry  of  France.  This  plague,  which 


560  FRAGMENTS  OP  SCIENCE. 

received  the  name  of  pebrine,  was  the  product  of  a  parasite 
which  first  took  possession  of  the  intestinal  canal  of  the 
silk-worm,  spread  throughout  its  body,  and  filled  the  sack 
which  ought  to  contain  the  viscid  matter  of  the  silk. 
Thus  smitten,  the  worm  would  go  automatically  through 
the  process  of  spinning  when  it  had  nothing  to  spin.  Pas- 
teur followed  this  parasitic  destroyer  from  year  to  year, 
and  led  by  his  singular  power  of  combining  facts  with  the 
logic  of  facts,  discovered  eventually  the  precise  phase  in 
the  development  of  the  insect  when  the  disease  which 
assailed  it  could  with  certainty  be  stamped  out.  Pasteur's 
devotion  to  this  inquiry  cost  him  dear.  He  restored  to 
France  her  silk  husbandry,  rescued  thousands  of  her 
population  from  ruin,  set  the  looms  of  Italy  also  to  work, 
but  emerged  from  his  labors  with  one  of  his  sides  per- 
manently paralyzed.  His  last  investigation  is  embodied  in 
a  work  entitled  "Studies  on  Beer,"  in  which  he  describes 
a  method  of  rendering  beer  permanently  unchangeable. 
That  method  is  not  so  simple  as  those  found  eifectual  with 
wine  and  vinegar,  but  the  principles  which  it  involves  are 
sure  to  receive  extensive  application  at  some  future  day. 

There  are  other  reflections  connected  with  this  subject 
which,  even  were  they  now  passed  over  without  remark, 
would  sooner  or  later  occur  to  every  thoughtful  mind  in 
this  assembly.  I  have  spoken  of  the  floating  dust  of  the 
air,  of  the  means  of  rendering  it  visible,  and  of  the  perfect 
immunity  from  putrefaction  which  accompanies  the  contact 
of  germless  infusions  and  moteless  air.  Consider  the  woes 
which  these  wafted  particles,  during  historic  and  pre-his- 
toricages,  have  inflicted  on  mankind; consider  the  loss  of  life 
in  hospitals  from  putrefying  wounds;  consider  the  loss  in 
places  where  there  are  plenty  of  wounds,  but  no  hospitals, 
and  in  the  ages  before  hospitals  were  any  where  founded;  con- 
sider the  slaughter  which  has  hitherto  followed  that  of  the 
battlefield,  when  those  bacterial  destroyers  are  let  loose, 
often  producing  a  mortality  far  greater  than  that  of  the 
battle  itself;  add  to  this  the  other  conception  that  in  times  of 
epidemic  disease  the  selfsame  floating  matter  has  frequently, 
if  not  always,  mingled  with  it  the  special  germs  which  pro- 
duce the  epidemic,  being  thus  enabled  to  sow  pestilence  and 
death  over  nations  and  continents — consider  all  this,  and 
you  will  come  with  me  to  the  conclusion  that  all  the  havoc 
of  war,  ten  times  multiplied,  would  be  evanescent  if  com- 
pared with  the  ravages  due  to  atmospheric  dust. 


FERMKNTATION.  561 

This  preventible  destruction  is  going  on  to-day,  and  it 
has  been  permitted  to  go  on  for  ages,  without  a  whisper  of 
information  regarding  its  cause  being  vouchsafed  to  the 
suffering  sentient  world.  We  have  been  scourged  by  invis- 
ible throngs,  attacked  from  impenetrable  ambuscades,  and 
it  is  only  to-day  that  the  light  of  science  is  being  let  in 
upon  the  murderous  dominion  of  our  foes.  Facts  like 
these  excite  in  me  the  thought  that  the  rule  and  govern- 
ance of  this  universe  are  different  from  what  we  in'  our 
youth  supposed  them  to  be — that  the  inscrutable  Power, 
at  once  terrible  and  beneficent,  in  whom  we  live  and  move 
and  have  our  being  and  our  end,  is  to  be  propitiated  by 
means  different  to  those  usually  resorted  to.  The  first 
requisite  toward  such  propitiation  is  knowledge;  the  second 
inaction,  shaped  and  illuminated  by  that  knowledge.  Of 
knowledge  we  already  see  the  dawn,  which  will  open  out 
by  and  by  to  perfect  day;  while  the  action  which  is  to 
follow  has  its  unfailing  source  and  stimulus  in  the  moral 
and  emotional  nature  of  man — in  his  desire  for  personal 
well-being,  in  his  sense  of  duty,  in  his  compassionate  sym- 
pathy with  the  sufferings  of  his  fellow-men.  "  How  often," 
says  Dr.  William  Budd  in  his  celebrated  work  on  Typhoid 
Fever — "  How  often  have  I  seen  in  past  days,  in  the  single 
narrow  chamber  of  the  day-laborer's  cottage  the  father  in 
the  coffin,  the  mother  in  the  sick-bed  in  muttering  delirium, 
and  nothing  to  relieve  the  desolation  of  the  children  but 
the  devotion  of  some  poor  neighbor,  who  in  too  many  cases 
paid  the  penalty  of  her  kindness  in  becoming  herself  the 
victim  of  the  same  disorder!"  From  the  vantage  ground 
already  won  I  look  forward  with  confident  hope  to  the 
triumph  of  medical  art  over  scenes  of  misery  like  that  here 
described.  The  cause  of  the  calamity  being  once  clearly 
revealed,  not  only  to  the  physician,  but  to  the  public, 
whose  intelligent  co-operation  is  absolutely  essential  to  suc- 
cess, the  final  victory  of  humanity  is  only  a  question  of 
time.  We  have  already  a  foretaste  of  that  victory  in  the 
triumphs  of  surgery  as  practiced  at  your  doors. 


562  FRAGMENTS  OF  SCIENCE. 

CHAPTER  XXXV. 

SPONTANEOUS    GENERATION.* 

WITHIN  ten  minutes'  walk  of  a  little  cottage  which  I 
have  recently  built  in  the  Alps,  there  is  a  small  lake,  fed 
by  the  melted  snows  of  the  upper  mountains.  During  the 
early  weeks  of  summer  no  trace  of  life  is  to  be  discerned  in 
this  water;  but  invariably  toward  the  end  of  Julv,  or  the 
beginning  of  August,  swarrns  of  tailed  organisms  are 
seen  enjoying  the  sun's  warmth  along  the  shallow  margins 
of  the  lake,  and  rushing  with  audible  patter  into  deeper 
water  at  the  approach  of  danger.  The  origin  of  this 
periodic  crowd  of  living  things  is  by  no  means  obvious. 
For  years  I  had  never  noticed  in  the  lake  either  an  adult 
frog,  or  the  smallest  fragment  of  frog  spawn;  so  that  were 
I  not  otherwise  informed,  I  should  have  found  the  conclu- 
sion of  Mathiole  a  natural  one,  namely,  that  tadpoles  are 
generated  in  lake  mud  by  the  vivifying  action  of  the  sun. 

The  checks  which  experience  alone  can  furnish  being 
absent,  the  spontaneous  generation  of  creatures  quite  as 
high  as  the  frog  in  the  scale  of  being  was  assumed  for  ages 
to  be  a  fact.  Here,  as  elsewhere,  the  dominant  mind  of 
Aristotle  stamped  its  notions  on  the  world  at  large.  For 
nearly  twenty  centuries  after  him  men  found  no  difficulty 
in  believing  in  cases  of  spontaneous  generation  which  would 
now  be  rejected  as  monstrous  by  the  most  fanatical  sup- 
porter of  the  doctrine.  Shell  fish  of  all  kinds  were  con- 
sidered to  be  without  parental  origin.  Eels  were  supposed 
to  spring  spontaneously  from  the  fat  ooze  of  the  Nile. 
Caterpillars  were  the  spontaneous  products  of  the  leaves  on 
which  they  fed;  while  winged  insects,  serpents,  rats,  and 
mice  were  all  thought  capable  of  being  generated  without 
sexual  intervention. 

The  most  copious  source  of  this  life  without  an 
ancestry  was  putrefying  flesh;  and,  lacking  the  checks 
imposed  by  fuller  investigation,  the  conclusion  that  flesh 
possesses  and  exerts  this  generative  power  is  a  natural  one. 
I  well  remember  when  a  child  of  ten  or  twelve  seeing  a 
joint  of  imperfectly  salted  beef  cut  into,  and  coils  of  mag- 
gots laid  bare  within  the  mass.  Without  a  moment's 

*  The  Nineteenth  Century,  January,  1878. 


SPONTANEOUS  OKNE11ATION.  563 

hesitation  I  jumped  to  the  conclusion  that  these  maggots 
had  been  spontaneously  generated  in  the  meat.  I  had  no 
knowledge  which  could  qualify  or  oppose  this  conclusion, 
and  for  the  time  it  was  irresistible.  The  childhood  of  the 
individual  typifies  that  of  the  race,  and  the  belief  here 
enunciated  was  that  of  the  world  for  nearly  two  thousand 
years. 

To  the  examination  of  this  very  point  the  celebrated 
Francesco  Redi,  physician  to  the  Grand  Dukes  Ferdinand 
II.  and  Cosmo  III.  of  Tuscany,  and  a  member  of  the  Acad- 
emy del  Cimento,  addressed  himself  in  1668.  He  had  seen 
the  maggots  of  putrefying  flesh,  and  reflected  on  their 
possible  origin.  But  he  was  not  content  with  mere  reflec- 
tion, nor  with  the  theoretic  guesswork  which  his  pred- 
ecessors had  founded  upon  their  imperfect  observations. 
Watching  meat  during  its  passage  from  freshness  to  decay, 
prior  to  the  appearance  of  maggots  he  invariably  observed 
flies  buzzing  round  the  meat  and  frequently  alighting  on 
it.  The  maggots,  he  thought,  might  be  the  half-developed 
progeny  of  these  flies. 

The  inductive  guess  precedes  experiment,  by  which, 
however,  it  must  be  finally  tested.  Redi  knew  this,  and 
acted  accordingly.  Placing  fresh  meat  in  a  jar  and  cover- 
ing the  mouth  with  paper,  he  found  that,  though  the 
meat  putrefied  in  the  ordinary  way,  it  never  bred  maggots, 
while  the  same  meat  placed  in  open  jars  soon  swarmed  with 
these  organisms.  For  the  paper  cover  he  then  substituted 
fine  gauze,  through  which  the  odor  of  the  meat  could  rise. 
Over  it  the  flies  buzzed,  and  on  it  they  laid  their  eggs,  but, 
the  meshes  being  too  small  to  permit  the  eggs  to  fall 
through,  no  maggots  were  generated  in  the  meat.  They 
were,  on  the  contrary,  hatched  upon  the  gauze.  By  a 
series  of  such  experiments  Redi  destroyed  the  belief  in  the 
spontaneous  generation  of  maggots  in  meat,  and  with  it 
doubtless  many  related  beliefs.  The  combat  was  con- 
tinued by  Vallisneri,  Schwarnmerdam,  and  Reaumur,  who 
succeeded  in  banishing  the  notion  of  spontaneous  gener- 
ation from  the  scientific  minds  of  their  day.  Indeed,  as 
regards  such  complex  organisms  as  those  which  formed 
the  subject  of  their  researches,  the  notion  was  banished 
forever. 

But  the  discovery  and  improvement  of  the  microscope, 
though  giving  a  death-blow  to  much  that  had  been  pre- 


564  FRAGMENTS  OF  SCIENCE. 

viously  written  and  believed  regarding  spontaneous  gener- 
ation, brought  also  into  view  a  world  of  life  formed  of 
individuals  so  minute — so  close  as  it  seemed  to  the  ultimate 
particles  of  matter — as  to  suggest  an  easy  passage  from 
atoms  to  organisms.  Animal  and  vegetable  infusions 
exposed  to  the  air  were  found  clouded  and  crowded  with 
creatures  far  beyond  the  reach  of  unaided  vision,  but  per- 
fectly visible  to  an  eye  strengthened  by  the  microscope. 
With  reference  to  their  origin  these  organisms  were  called 
"  Infusoria."  Stagnant  pools  were  found  full  of  them,  and 
the  obvious  difficulty  of  assigning  a  germinal  origin  to 
existences  so  minute  furnished  the  precise  condition 
necessary  to  give  new  play  to  the  notion  of  heterogenesis 
or  spontaneous  generation. 

The  scientific  world  was  soon  divided  into  two  hostile 
camps,  the  leaders  of  which  only  can  here  be  briefly 
alluded  to.  On  the  one  side,  we  have  Buffon  and  Need- 
ham,  the  former  postulating  his  "  organic  molecules,"  and 
the  latter  assuming  the  existence  of  a  special  "vegetative 
force  "  which  drew  the  molecules  together  so  as  to  form 
living  things.  On  the  other  side,  we  have  the  celebrated 
Abbe  Lazzaro  Spallanzani,  who  in  1777  published  results 
counter  to  those  announced  by  Need  ham  in  1748,  and 
obtained  by  methods  so  precise  as  to  completely  overthrow 
the  convictions  based  upon  the  labors  of  his  predecessor. 
Charging  his  flasks  with  organic  infusions,  he  sealed  their 
necks  with  the  blowpipe,  subjected  them  in  this  condition 
to  the  heat  of  boiling  water,  and  subsequently  exposed 
them  to  temperatures  favorable  to  the  development  of  life. 
The  infusions  continued  unchanged  for  months,  and  when 
the  flasks  were  subsequently  opened  no  trace  of  life  was 
fonnd. 

Here  I  may  forestall  matters  so  far  as  to  say  that  the  success 
of  Spallanzani's  experiments  depended  wholly  on  the  local- 
ity in  which  he  worked.  The  air  around  him  must  have 
been  free  from  the  more  obdurate  infusorial  germs,  for 
otherwise  the  process  he  followed  would,  as  was  long  after- 
ward proved  by  Wymau,  have  infallibly  yielded  life.  But 
his  refutation  of  the  doctrine  of  spontaneous  generation  is 
not  the  less  valid  on  this  account.  Nor  is  it  in  any  way 
upset  by  the  fact,  that  others  in  repeating  his  experiments 
obtained  life  where  he  obtained  none.  Rather  is  the  refu- 
tation strengthened  by  such  differences.  Given  two  experi- 


SPONTANEOUS  GENERATION.  565 


qually  skillful  and   equally  careful,  operating  in 
places  on  the  same  infusion,  in  the  same  way,  and 


m  enters  e 

different  places  on  the  same  infusion,  in  the  same  way, 
assuming  the  one  to  obtain  life  while  the  other  fails  to 
obtain  it;  then  its  well-established  absence  in  the  one  case 
proves  that  some  ingredient  foreign  to  the  infusion  must 
be  its  cause  in  the  other. 

Spallanzani's  sealed  flasks  contained  but  small  quantities 
of  air,  and  as  oxygen  was  afterward  shown  to  be  generally 
essential  to  life,  it  was  thought  that  the  absence  of  life 
observed  by  Spallanzaui  might  have  been  due  to  the  lack  of 
this  vitalizing  gas.  To  dissipate  this  doubt,  Schulze  in 
1836  half  filled  a  flask  with  distilled  water  to  which  animal 
and  vegetable  matters  were  added.  First  boiling  his  infu- 
sion to  destroy  whatever  life  it  might  contain,  Schulze 
sucked  daily  into  his  flask  air  which  has  passed  through  a 
series  of  bulbs  containing  concentrated  sulphuric  acid, 
where  all  germs  of  life  suspended  in  the  air  were  supposed 
to  be  destroyed.  From  May  to  August  this  process  was 
continued  without  any  development  of  infusorial  life. 

Here  again  the  success  of  Schulze  was  due  to  his  work- 
ing in  comparatively  pure  air,  but  even  in  such  air  his 
experiment  is  a  very  risky  one.  Germs  will  pass  un  wetted 
and  unscathed  through  sulphuric  acid  unless  the  most 
special  care  is  taken  to  detain  them.  I  have  repeatedly 
failed,  by  repeating  Schulze's  experiments,  to  obtain  his 
results.  Others  have  failed  likewise.  The  air  passes  in 
bubbles  through  the  bulbs,  and  to  render  the  method 
secure,  the  passage  of  the  air  must  be  so  slow  as  to  cause 
the  whole  of  its  floating  matter,  even  to  the  very  core  of 
each  bubble,  to  touch  the  surrounding  liquid.  But  if  this 
precaution  be  observed,  water  will  be  found  quite  as  effect- 
ual as  sulphuric  acid.  By  the  aid  of  an  air-pump  in  a 
highly  infective  atmosphere  I  have  thus  drawn  air  for 
weeks  without  intermission,  first  through  bulbs  containing 
water,  and  afterward  through  vessels  containing  organic 
infusions,  without  any  appearance  of  life.  The  germs 
were  not  killed  by  the  water,  but  they  were  effectually  in- 
tercepted, while  the  objection  that  the  air  had  been  injured 
by  being  brought  into  contact  with  strongly  corrosive 
substances  was  avoided. 

The  brief  paper  of  Schulze,  published  in  Poggendorf's 
Annalen  for  1836,  was  followed  in  1837  by  another  short 
and  pregnant  communication  by  Sch.wa.uu,  Kedij  as  we 


566  FRAGMENTS  OF  SCIENCE. 

have  seen,  traced  the  maggots  of  putrefying  flesh  to  the 
eggs  of  flies.  But  he  did  not  and  he  could  not  know  the 
meaning  of  putrefaction  itself.  He  had  not  the  instru- 
mental means  to  inform  him  that  it  also  is  a  phenomenon 
attendant  on  the  development  of  life.  This  was  first 
proved  in  the  paper  now  alluded  to.  Schwann  placed 
flesh  in  a  flask  filled  to  one-third  of  its  capacity  with  water, 
sterilized  the  flask  by  boiling,  and  then  supplied  it  for 
months  with  calcined  air.  Throughout  this  time  there 
appeared  no  mold,  no  infusoria,  no  putrefaction;  the 
flesh  remained  unaltered,  while  the  liquid  continued  as 
clear  as  it  was  immediately  after  boiling.  Schwann  then 
varied  his  experimental  argument,  with  no  alteration  in 
the  result.  His  final  conclusion  was,  that  putrefaction  is 
due  to  decompositions  of  organic  matter  attendant  on  the 
multiplication  therein  of  minute  organisms.  These  organ- 
isms were  derived  not  from  the  air,  but  from  something 
contained  in  the  air,  which  was  destroyed  by  a  sufficiently1 
high  temperature.  There  never  was  a  more  determined 
opponent  of  the  doctrine  of  spontaneous  generation  than 
Schwann,  though  a  strange  attempt  was  made  a  year  and 
a  half  ago  to  enlist  him  and  others  equally  opposed  to  it  on 
the  side  of  the  doctrine. 

The  physical  character  of  the  agent  which  produces 
putrefaction  was  further  revealed  by  Helmholtz  in  1843. 
By  means  of  a  membrane  he  separated  a  sterilized  putres- 
cible  liquid  from  a  putrefying  one.  The  sterilized  infusion 
remained  perfectly  intact.  Hence  it  was  not  the  liquid  of 
the  putrefying  mass — for  that  could  freely  diffuse  through 
the  membrane — but  something  contained  in  the  liquid, 
and  which  was  stopped  by  the  membrane,  that  caused 
the  putrefaction.  In  1854  Schroeder  and  Von  Dusch 
struck  into  this  inquiry,  which  was  subsequently  followed 
up  by  Schroeder  alone.  These  able  experimenters  employed 
plugs  of  cotton-wool  to  filter  the  air  supplied  to  their  in- 
fusions. Fed  with  such  air,  in  the  great  majority  of  cases 
the  putrescible  liquids  remained  perfectly  sweet  after 
boiling.  Milk  formed  a  conspicuous  exception  to  the 
general  rule.  It  putrefied  after  boiling,  though  supplied 
with  carefully  filtered  air.  The  researches  of  Schroeder 
bring  us  up  to  the  year  1859. 

In  that  year  a  book  was  published  which  seemed  to 
overturn  some  of  the  best  established  facts  of  previous 


SPONTANEOUS  GENERATION.  567 

investigators.  Its  title  was  Heterogenie,  and  its  author 
was  F.  A.  Pouchet,  director  of  the  Museum  of  Natural 
History  at  Rouen.  Ardent,  laborious,  learned,  full  not 
only  of  scientific  but  of  metaphysical  fervor,  he  threw 
his  whole  energy  into  the  inquiry.  Never  did  a  subject 
require  the  exercise  of  the  cold,  critical  faculty  more  than 
this  o«e — calm  study  in  the  unraveling  of  complex  phe- 
nomena, care  in  the  preparation  of  experiments,  care 
in  their  execution,  skillful  variation  of  conditions,  and 
incessant  questioning  of  results  until  repetition  had  placed 
them  beyond  doubt  or  question.  To  a  man  of  Pouchet's 
temperament  the  subject  was  full  of  danger — danger  not 
lessened  by  the  theoretic  bias  with  which  he  approached  it. 
This  is  revealed  by  the  opening  words  of  his  preface: 
"  Lorsque,  par  la  meditation,  il  fut  evident  pour  rnoi  que 
la  generation  spontanee  etait  encore  Tun  des  moyeus 
qu'emploie  la  nature  pour  la  reproduction  des  etres,  je 
m'appliquai  a  decouvrir  par  quels  proceeds  on  pouvait 
parvenir  a  en  mettre  les  pheuomenes  en  evidence."  It  is 
needless  to  say.  that  such  a  prepossession  required  a  strong 
curb.  Pouchet  repeated  the  experiments  of  Schulze  and 
Schwann  with  results  diametrically  opposed  to  theirs.  He 
heaped  experiment  upon  experiment  and  argument  upon 
argument,  spicing  with  the  sarcasm  of  the  advocate  the 
logic  of  the  man  of  science.  In  view  of  the  multitudes 
required  to  produce  the  observed  results,  he  ridiculed  the 
assumption  of  atmospheric  germs.  This  was  one  of  his 
strongest  points.  "  Si  les  Proto-organismes  que  nous  voyons 
pulluler  partout  et  dans  tout,  avaient  leurs  germes  dis- 
setnines  dans  1 'atmosphere,  dans  la  proportion  mathema- 
tiquement  indispensable  a  cet  effet,  Fair  en  serait  totalement 
obscurci,  car  ils  devraient  s'y  trouver  beaucoup  plus  eerres 
que  les  globules  d'eau  qui  forment  nos  images  epais.  II 
n'y  a  pas  la  la  moindre  exageration."  Recurring  to  the 
subject,  he  exclaims:  "L'air  clans  lequel  nous  vivonsaurait 
presque  la  densitc  du  fer."  There  is  often  a  virulent  con- 
tagion in  a  confident  tone,  and  this  hardihood  of  argumen- 
tative assertion  was  sure  to  influence  minds  swayed  not  by 
knowledge,  but  by  authority.  Had  Pouchet  known  that 
"  the  blue  ethereal  sky"  is  formed  of  suspended  particles, 
through  which  the  sun  freely  shines,  he  would  hardly  have 
ven  tit  red  upon  this  line  of  argument. 

Pouchet's  pursuit  of  this  inquiry  strengthened  the  con- 


568  FRAGMENTS  OF  SCIENCE. 

viction  with  which  he  began  it,  and  landed  him  in  down- 
right credulity  in  the  end.  I  do  not  question  his  ability  as 
an  observer,  but  the  inquiry  needed  a  disciplined  experi- 
menter. This  latter  implies  not  mere  ability  to  look  at 
things  us  Nature  offers  them  to  our  inspection,  but  to  force 
her  to  show  herself  under  conditions  prescribed  by  the 
experimenter  himself.  Here  Pouchet  lacked  the  necessary 
discipline.  Yet  the  vigor  of  his  onset  raised  clouds  of 
doubt,  which  for  a  time  obscured  the  whole  field  of 
inquiry.  So  difficult  indeed  did  the  subject  seem,  and  so 
incapable  of  definite  solution,  that  when  Pasteur  made 
known  his  intention  to  take  it  up,  his  friends  Biot  and 
Dumas  expressed  their  regret,  earnestly  exhorting  him  to 
set  a  definite  and  rigid  limit  to  the  time  he  purposed 
spending  in  this  apparently  unprofitable  field.* 

Schooled  by  his  education  as  a  chemist,  and  by  special 
researches  on  the  closely  related  question  of  fermentation, 
Pasteur  took  up  this  subject  under  particularly  favorable 
conditions.  His  work  and  his  culture  had  given  strength 
and  finish  to  his  natural  apitudes.  In  1862,  accordingly, 
he  published  a  paper  "  On  the  Organized  Corpuscles  exist- 
ing in  the  Atmosphere,"  which  must  forever  remain 
classical.  By  the  most  ingenious  devices  he  collected  the 
floating  particles  of  the  air  surrounding  his  laboratory  in 
the  Eue  d'Ulm,  and  subjected  them  to  microscopic 
examination.  Many  of  them  he  found  to  be  organized 
particles.  Sowing  them  in  sterilized  infusions,  he  obtained 
abundant  crops  of  microscopic  organisms.  By  more  refined 
methods  he  repeated  and  confirmed  the  experiments  of 
Schwann,  which  had  been  contested  by  Pouchet,  Monte- 
gazza,  Joly,  and  Musset.  He  also  confirmed  the  experi- 
ments of  Schroeder  and  Von  Dusch.  He  showed  that  the 
cause  which  communicated  life  to  his  infusions  was  not 
uniformly  diffused  through  the  air;  that  there  were  aerial 
interspaces  which  possessed  no  power  to  generate  life. 
Standing  on  the  Mer  de  Glace,  near  the  Montanvert,  he 
snipped  off  the  ends  of  a  number  of  hermetically  sealed 
flasks  containing  organic  infusions.  One  out  of  twenty  of 

*  "Je  ne  conseillerais  a  personne,"  said  Dumas  to  his  already 
famous  pupil,  "  de  rester  trop  longtemps  dans  ce  sujet." — Annales 
de  Chimie  et  de  Physique,  1862,  vol.  Ixiv.,  p.  22.  Since  that  time  the 
illustrious  perpetual  secretary  of  the  Academy  of  Sciences  has  Iia4 
good  reason  to  revise  this  "  counsel," 


SPONTANEOUS  GENERATION.  569 

the  flasks  thus  supplied  with  glacier  air  showed  signs  of  life 
afterward,  while  eight  out  of  twenty  of  the  same  infusions, 
supplied  with  the  air  of  the  plains,  became  crowded  with 
life.  He  took  his  flasks  into  the  caves  under  the  Obser- 
vatory of  Paris,  and  found  the  still  air  in  these  caves 
devoid  of  generative  power.  These  and  other  experiments, 
carried  out  with  a  severity  perfectly  obvious  to  the  instructed 
scientific  reader,  and  accompanied  by  a  logic  equally 
severe,  restored  the  conviction  that,  even  in  these  lower 
readies  of  the  scale  of  being,  life  does  not  appear  without 
the  operation  of  antecedent  life. 

The  main  position  of  Pasteur  has  been  strengthened  by 
practical  researches  of  the  most  momentous  kind.  He  has 
applied  the  knowledge  won  from  his  inquiries  to  the 
preservation  of  wine  and  beer,  to  the  manufacture  of 
vinegar,  to  the  staying  of  the  plague  which  threatened 
utter  destruction  of  the  silk  husbandry  of  France,  and  to 
the  examination  of  other  formidable  diseases  which  assail 
the  higher  animals,  including  man.  His  relation  to  the 
improvements  which  Professor  Lister  has  introduced  into 
surgery,  is  shown  by  a  letter  quoted  in  his  Etudes  sur  la 
Biere.*  Professor  Lister  there  expressly  thanks  Pasteur 
for  having  given  him  the  only  principle  which  could  have 
conducted  the  antiseptic  system  to  a  successful  issue.  The 
strictures  regarding  defects  of  reasoning,  to  which  we  have 
been  lately  accustomed,  throw  abundant  light  upon  their 
author,  but  no  shade  upon  Pasteur. 

Eedi,  as  we  have  seen,  proved  the  maggots  of  putrefying 
flesh  to  be  derived  from  the  eggs  of  flies;  Schwann  proved 
putrefaction  itself  to  be  the  concomitant  of  far  lower  forms 
of  life  than  those  dealt  with  by  Redi.  Our  knowledge 
here,  as  elsewhere  in  connection  with  this  subject,  has  been 
vastly  extended  by  Professor  Cohn,  of  Breslau.  "  No 
putrefaction,"  he  says,  "  can  occur  in  a  nitrogenous  sub- 
stance if  its  bacteria  be  destroyed  and  new  ones  prevented 
from  entering  it.  Putrefaction  begins  as  soon  as  bacteria, 
even  in  the  smallest  numbers,  are  admitted  either  accident- 
ally or  purposely.  It  progresses  in  direct  proportion  to  the 
multiplication  of  the  bacteria,  it  is  retarded  when  they 
exhibit  low  vitality,  and  is  stopped  by  all  influences  which 
either  hinder  their  development  or  kill  them.  All  bacte- 

*  P.  43, 


570  FRAGMENTS  OF  SCIENCE. 

ricidal  media  are  therefore  antiseptic  and  disinfecting."* 
It  was  these  organisms  acting  in  wound  and  abscess  which 
so  frequently  converted  our  hospitals  into  charnel-houses, 
and  it  is  their  destruction  by  the  antiseptic  system  that 
now  renders  justifiable  operations  which  no  surgeon  would 
have  attempted  a  few  years  ago.  The  gain  is  immense — 
to  the  practicing  surgeon  as  well  as  to  the  patient  practiced 
upon.  Contrast  the  anxiety  of  never  feeling  sure  whether 
the  most  brilliant  operation  might  not  be  rendered 
nugatory  by  the  access  of  a  few  particles  of  unseen  hospital 
dust,  with  the  comfort  derived  from  knowledge  that  all 
power  of  mischief  on  the  part  of  such  dust  has  been  surely 
and  certainly  annihilated.  But  the  action  of  living  con- 
tagia  extends  beyond  the  domain  of  the  surgeon.  The 
power  of  reproduction  and  indefinite  self-multiplication 
which  is  characteristic  of  living  things,  coupled  with  the 
undeviating  fact  of  contagia  "breeding  true,'' has  given 
strength  and  consistency  to  a  belief  long  entertained  by 
penetrating  minds,  that  epidemic  diseases  generally  are 
the  concomitants  of  parasitic  life.  "  There  begins  to  be 
faintly  visible  to  us  a  vast  and  destructive  laboratory  of 
nature  wherein  the  diseases  which  are  most  fatal  to  animal 
life,  and  the  changes  to  which  dead  organic  matter  is 
passively  liable,  appear  bound  together  by  what  must  at 
least  be  called  a  very  close  analogy  of  causatipu."  f  Accord- 
ing to  this  view,  which,  as  I  have  said,  is  daily  gaining 
converts,  a  contagious  disease  may  be  defined  as  a  conflict 
between  the  person  smitten  by  it  and  a  specific  organism 
which  multiplies  at  his  expense,  appropriating  his  air  and 
moisture,  disintegrating  his  tissues,  or  poisoning  him  by 
the  decompositions  incident  to  its  growth. 


During  the  ten  years  extending  from  1859  to 
researches  on  radiant  heat  in  its  relations  to  the  gaseous 
form  of  matter  occupied  my  continual  attention.  When 
air  was  experimented  on,  I  had  to  cleanse  it  effectually  of 

*  In  his  last  excellent  memoir  Colin  expresses  himself  thus:  "  Wer 
noch  heut  die  Faulniss  von  einer  spontanen  Dissociation  der  Pro- 
teinmolecule,  oder  von  einem  unorganisirten  Ferment  ableitet,  oder 
gar  aus  '  Stickstoffsplittern '  die  Balken  zur  Stiitze  seiner  Faul- 
nisstheorie  zu  zinnnern  versucht,  hat  zuerst  den  Satz  'keine 
Faulniss  ohne  Bacterium  Termo '  zu  widerlegen." 

\  Report  of  the  Medical  Officer  of  the  Privy  Council,  1874,  p,  5, 


SPONTANEOUS  GENERATION.  571 

floating  matter,  and  while  doing  so  I  was  surprised  to 
notice  that,  at  the  ordinary  rate  of  transfer,  such  matter 
passed  freely  through  alkalis,  acids,  alcohols,  and  ethers. 
The  eye  being  kept  sensitive  by  "darkness,  a  concentrated 
beam  of  light  was  found  to  be  a  most  searching  test  for 
suspended  matter  both  in  water  and  in  air — a  test  indeed 
indefinitely  more  searching  and  severe  than  that  furnished  by 
the  most  powerful  microscope.  With  the  aid  of  such  a 
beam  I  examined  air  filtered  by  cotton-wool;  air  long  kept 
free  from  agitation,  so  as  to  allow  the  floating  matter  to 
subside;  calcined  air,  and  air  filtered  by  the  deeper  cells  of 
the  human  lungs.  In  all  cases  the  correspondence  between 
my  experiments  and  those  of  Schroeder,  Pasteur,  and 
Lister  in  regard  to  spontaneous  generation  was  perfect. 
The  air  which  they  found  inoperative  was  proved  by  the 
luminous  beam  to  be  optically  pure  and  therefore  germless. 
Having  worked  at  the  subject  both  by  experiment  and 
reflection,  on  Friday  evening,  January  21,  1870,  1  brought 
it  before  the  members  of  the  Royal  Institution.  Two  or 
three  months  subsequently,  for  sufficient  practical  reasons, 
I  ventured  to  direct  public  attention  to  the  subject  in  a 
letter  to  the  Times.  Such  was  my  first  contact  with  this 
important  question. 

This  letter,  I  believe,  gave  occasion  for  the  first  public 
utterance  of  Dr.  Bastian  in  relation  to  this  subject.  He 
did  me  the  honor  to  inform  me,  as  others  had  informed 
Pasteur,  that  the  subject  "  pertains  to  the  biologist  and 
physician/'  He  expressed  "  amazement "  at  my  reasoning, 
and  warned  me  that  before  what  I  had  done  could  be 
undone  "  much  irreparable  mischief  might  be  occasioned." 
With  far  less  preliminary  experience  to  guide  and  warn 
him,  the  English  heterogenist  was  far  bolder  than  Pouchet 
in  his  experiments,  and  far  more  adventurous  in  his  con- 
clusions. With  organic  infusions  he  obtained  the  results 
of  his  celebrated  predecessor,  but  he  did  much  more — the 
atoms  and  molecules  of  inorganic  liquids  passing  under 
his  manipulation  into  those  more  "  complex  chemical 
compounds/'  which  we  dignify  by  calling  them  "living 
organisms."  *  As  regards  the  public  who  take  an  interest 

*  '  It  is  further  held  that  bacteria  or  allied  organisms  are  prone  to 
be  engendered  as  correlative  products,  coming  into  existence  in  the 
several  fermentations,  just  as  independently  as  other  less  complex 
chemical  compounds." — Bastiau,  Trans,  of  Pathological  Society,  vol. 
xxvi.,  258. 


5?2  FRAGMENTS  OF  SCIENCE. 

in  such  things,  and  apparently  also  as  regards  a  large 
portion  of  the  medical  profession,  our  clever  countryman 
succeeded  in  restoring  the  subject  to  a  state  of  uncertainty 
similar  to  that  which  followed  the  publication  of  Pouchet's 
volume  in  1859. 

It  is  desirable  that  this  uncertainty  should  be  removed 
from  all  minds,  and  doubly  desirable  on  practical  grounds 
that  it  should  be  removed  from  the  minds  of  medical  men. 
In  the  present  article,  therefore,  I  propose  discussing  this 
question  face  to  face  with  some  eminent  and  fair-minded 
member  of  the  medical  profession  who,  as  regards 
spontaneous  generation,  entertains  views  adverse  to  mine. 
Such  a  one  it  would  be  easy  to  name;  but  it  is  perhaps  better 
to  rest  in  the  impersonal.  I  shall  therefore  simply  call 
my  proposed  co-inquirer  my  friend.  With  him  at  my 
side,  I  shall  endeavor,  to  the  best  of  my  ability,  so  to  con- 
duct this  discussion  that  he  who  runs  may  read  and  that 
he  who  reads  may  understand. 

Let  us  begin  at  the  beginning.  I  ask  my  friend  to  step 
into  the  laboratory  of  the  Eoyal  Institution,  where  I  place 
before  him  a  basin  of  thin  turnip  slices  barely  covered 
with  distilled  water  kept  at  a  temperature  of  130  degrees 
Fahr.  After  digesting  the  turnip  for 
four  or  five  hours  we  pour  off  the 
liquid,  boil  it,  filter  it,  and  obtain  an 
infusion  as  clear  as  filtered  drinking 
water.  We  cool  the  infusion,  test  its 
specific  gravity,  and  find  it  to  be  ]OOG 
or  higher — water  being  1000.  A 
number  of  small  clean  empty  flasks, 
of  the  shape  shown  on  the  margin, 
are  .before  us.  One  of  them  is 
slightly  warmed  with  a  spirit-lamp, 
and  its  open  end  is  then  dipped  into 
turnip  the  infusion.  The  warmed 
glass  is  afterward  chilled,  the  air  within  the  flasks  cools, 
contracts,  and  is  followed  in  its  contraction  by  the  infusion. 
Thus  we  get  a  small  quantity  of  liquid  into  the  flask. 
We  now  heat  this  liquid  carefully.  Steam  is  produced, 
which  issues  from  the  open  neck,  carrying  the  air  of  the 
flask  along  with  it.  After  a  few  gecondsy  ebullition,  the 
open  neck  is  again  plunged  into  the  infusion.  The  steam 
within  the  flask  condenses,  the  liquid  enters  to  supply  its 


SPONTANEOUS  GENERATION.  573 

place,  and  in  this  way  we  fill  our  little  flask  to  about  four- 
fifths  of  its  volume.  This  description  is  typical;  we  may 
thus  fill  a  thousand  flasks  with  a  thousand  different  infu- 
sions. 

I  now  ask  my  friend  to  notice  a  trough  made  of  sheet 
copper,  with  two  rows  of  handy  little  Bunsen  burners 
underneath  it.  This  trough,  or  bath,  is  nearly  filled  with 
oil;  a  piece  of  thin  plank  constitutes  a  kind  of  lid  for  the 
oil-bath.  The  wood  is  perforated  with  circular  apertures 
wide  enough  to  allow  our  small  flask  to  pass  through  and 
plunge  itself  in  the  oil,  which  has  been  heated,  say,  to  250 
degrees  Fahr.  Clasped  all  round  by  the  hot  liquid,  the 
infusion  in  the  flask  rises  to  its  boiling  point,  which  is  not 
sensibly  over  212  degrees  Fahr.  Steam  issues  from  the 
open  neck  of  the  flask,  and  the  boiling  is  continued  for 
five  minutes.  With  a  pair  of  small  brass  tongs,  an  assistant 
now  seizes  the  neck  near  its  junction  with  the  flask,  and 
partially  lifts  the  latter  out  of  the  oil.  The  steam  does 
not  cease  to  issue,  but  its  violence  is  abated.  With  a 
second  pair  of  tongs  held  in  one  hand,  the  neck  of  the 
flask  is  seized  close  to  its  open  end,  while  with  the  other 
hand  a  Bunsen's  flame  or  an  ordinary  spirit  flame  is  brought 
under  the  middle  of  the  neck.  The  glass  reddens,  whitens, 
softens,  and  as  it  is  gently  drawn  out  the  neck  diminishes 
in  diameter,  until  the  canal  is  completely  blocked  up.  The 
tongs  with  the  fragment  of  severed  neck  being  withdrawn, 
the  flask,  with  its  contents  diminished  by  evaporation,  is 
lifted  from  the  oil-bath  perfectly  sealed  hermetically. 

Sixty  such  flasks  filled,  boiled,  and  sealed  in  the  manner 
described,  and  containing  strong  infusions  of  beef,  mutton, 
turnip,  and  cucumber,  are  carefully  packed  in  sawdust, 
and  transported  to  the  Alps.  Thither,  to  an  elevation  of 
about  7,000  feet  above  the  sea,  I  invite  my  co-inquirer  to 
accompany  me.  It  is  the  month  of  July,  and  the  weather 
is  favorable  to  putrefaction.  We  open  our  box  at  the  Bel- 
Alp,  and  count  out  fifty-four  flasks,  with  their  liquids  as 
clear  as  filtered  drinking  water.  In  six  flasks,  however, 
the  infusion  is  found  muddy.  We  closely  examine  these, 
and  discover  that  every  one  of  them  has  had  its  fragile  end 
broken  off  in  the  transit  from  London.  Air  has  entered 
the  flasks,  and  the  observed  muddiness  is  the  result.  My 
colleague  knows  as  well  as  I  do  what  this  means.  Examined 
with  a  pocket-lens,  or  even  with  a  microscope  of  insufficient 


574  FRAGMENTS  OF  SCIENCE. 

power,  nothing  is  seen  in  the  muddy  liquid;  but  regarded 
with  a  magnifying  power  of  a  thousand  diameters  or  so, 
what  an  astonishing  appearance  does  it  present!  Leeuwen- 
hoek  estimated  the  population  of  a  single  drop  of  stagnant 
water  at  500,000,000:  probably  the  population  of  a  drop  of 
our  turbid  infusion  would  be  this  many  times  multiplied. 
The  field  of  the  microscope  is  crowded  with  organisms, 
some  wabbling  slowly,  others  shooting  rapidly  across  the 
microscropic  field.  They  dart  hither  and  thither  like  a 
rain  of  minute  projectiles;  they  pirouette  and  spin  so 
quickly  round,  that  the  retention  of  the  retinal  impression 
transforms  the  little  living  rod  into  a  twirling  wheel.  And 
yet  the  most  celebrated  naturalists  tell  us  they  are  vege- 
tables. From  the  rod-like  shape  which  they  so  frequently 
assume,  these  organisms  are  called  "  bacteria  " — a  term,  be 
it  here  remarked,  which  covers  organisms  of  very  diverse 
kinds. 

Has  this  multitudinous  life  been  spontaneously  generated 
in  these  six  flasks,  or  is  it  the  progeny  of  living  germinal 
matter  carried  into  the  flasks  by  the  entering  air?  If  the 
infusions  have  a  self-generative  power,  how  are  the  sterility 
and  consequent  clearness  of  the  fifty-four  uninjured  flasks 
to  be  accounted  for?  My  colleague  may  urge — and  fairly 
urge — that  the  assumption  of  germinal  matter  is  by  no 
means  necessary;  that  the  air  itself  may  be  the  one  thing 
needed  to  wake  up  the  dormant  infusions.  We  will 
examine  this  point  immediately.  But  meanwhile  I  would 
remind  him  that  I  am  working  on  the  exact  lines  laid 
down  by  our  most  conspicuous  heterogenist.  He  distinctly 
affirms  that  the  withdrawal  of  the  atmospheric  pressure 
above  the  infusion  favors  the  production  of  organisms; 
and  he  accounts  for  their  absence  in  tins  of  preserved 
meat,  fruit,  and  vegetables,  by  the  hypothesis  that  fermen- 
tation has  begun  in  such  tins,  that  gases  have  been  gener- 
ated, the  pressure  of  which  has  stifled  the  incipient  life  and 
stopped  its  further  development.*  This  is  the  new  theory 
of  preserved  meats.  Had  its  author  pierced  a  tin  of  pre- 
served meat,  fruit,  or  vegetable  under  water  with  the  view 
of  testing  its  truth,  he  would  have  found  it  erroneous.  In 
well-preserved  tins  he  would  have  found,  not  an  outrush  of 
gas,  but  an  inrush  of  water.  I  have  noticed  this  recently 

*  Beginnings  of  Life,  vol.  i.,  p.  418. 


SPONTANEOUS  GENERATION.  575 

in  tins  which  have  lain  perfectly  good  for  sixty-three  years 
in  the  Royal  Institution.  Modern  tins,  subjected  to  the 
same  test,  yielded  the  same  result.  From  time  to  time, 
moreover,  during  the  last  two  years,  I  have  placed  glass 
tubes,  containing  clear  infusions  of  turnip,  hay,  beef,  and 
mutton,  in  iron  bottles,  and  subjected  them  to  air-pressures 
varying  from  ten  to  twenty-seven  atmospheres — pressures, 
it  is  needless  to  say,  far  more  than  sufficient  to  tear  a 
preserved  meat  tin  to  shreds.  After  ten  days  these  infusions 
were  taken  from  their  bottles  rotten  with  putrefaction 
and  teeming  with  life.  Thus  collapses  an  hypothesis 
which  had  no  rational  foundation,  and  which  could  never 
have  seen  the  light  had  the  slightest  attempt  been  made  to 
verify  it. 

Our  fifty-four  vacuous  and  pellucid  flasks  also  declare 
against  the  heterogenist.  We  expose  them  to  a  warm 
Alpine  sun  by  day,  and  at  night  we  suspend  them  in  a 
warm  kitchen.  Four  of  them  have  been  accidentally 
broken;  but  at  the  end  of  a  month  we  find  the  fifty 
remaining  ones  as  clear  as  at  the  commencement.  There 
is  no  sign  of  putrefaction  or  of  life  in  any  of  them.  We 
divide  these  flasks  into  two  groups  of  twenty-three  and 
twenty-seven  respectively  (tin  accident  of  counting  rendered 
the  division  uneven).  The  question  now  is  whether  the 
admission  of  air  can  liberate  any  generative  energy  in  the 
infusions.  Our  next  experiment  will  answer  this  question 
and  something  more.  We  carry  the  flasks  to  a  hayloft, 
and  there,  with  a  pair  of  steel  pliers,  snip  off  the  sealed 
ends  of  the  group  of  three-and-twenty.  Each  snipping  off 
is  of  course  followed  by  an  inrush  of  air.  We  now  carry 
our  twenty-seven  flasks,  our  pliers,  and  a  spirit-lamp,  to  a 
ledge  overlooking  the  Aletsch  glacier,  about  200  feet 
above  the  hayloft,  from  which  ledge  the  mountain  falls 
almost  precipitously  to  the  northeasc  for  about  a  thousand 
feet.  A  gentle  wind  blows  toward  us  from  the  northeast 
— that  is,  across  the  crests  and  snow-fields  of  the  Oberland 
mountains.  We  are  therefore  bathed  by  air  which  must 
have  been  for  a  good  while  out  of  practical  contact  with 
either  animal  or  ^vegetable  life.  I  stand  carefully  to 
leeward  of  the  flasks,  for  no  dust  or  particle  from  my 
clothes  or  body  must  be  blown  toward  them.  An  assistant 
ignites  the  spirit-lamp,  into  the  flame  of  which  I  plunge 
the  pliers,  thereby  destroying  all  attached  germs  or 


576  FRAGMENTS  OF  SCIENCE. 

organisms.  Then  I  snip  off  the  sealed  end  of  the 
flask.  Prior  to  every  snipping  the  same  process  is  gone 
through,  no  flask  being  opened  without  the  previous 
cleansing  of  the  pliers  by  the  flame.  In  this  way  we 
charge  our  seven-and-twenty  flasks  with  clean,  vivifying 
mountain  air. 

We  place  the  fifty  flasks,  with  their  necks  open,  over  a 
kitchen  stove,  in  a  temperature  varying  from  50  to  90 
degrees  Fahr.,  and  in  three  days  find  twenty-one  out  of 
the  twenty-three  flasks  opened  on  the  hayloft  invaded  by 
organisms — two  only  of  the  group  remaining  free  from 
them.  After  three  weeks'  exposure  to  precisely  the  same 
conditions,  not  one  of  the  twenty-seven  flasks  opened  in  free 
air  had  given  way.  No  germ  from  the  kitchen  air  had 
ascended  the  narrow  necks,  the  flasks  being  shaped  to  pro- 
duce this  result.  They  are  still  in  the  Alps,  as  clear,  I 
doubt  not,  and  as  free  from  life  as  they  were  when  sent  off 
from  London.* 

What  is  rny  colleague's  conclusion  from  the  experiment 
before  us?  Twenty-seven  putrescible  infusions,  first  in 
vacuo,  and  afterward  supplied  with  the  most  invigorating 
air,  have  shown  no  sign  of  putrefaction  or  of  life.  And 
as  to  the  others,  I  almost  shrink  from  asking  him  whether 
the  hayloft  has  rendered  them  spontaneously  generative. 
Is  not  the  inference  here  imperative  that  it  is  not  the 
air  of  the  loft — which  is  connected  through  a  constantly 
open  door  with  the  general  atmosphere — but  something 
contained  in  the  air,  that  has  produced  the  effects 
observed?  What  is  this  something?  A  sunbeam  entering 
through  a  chink  in  the  roof  or  wall,  and  traversing  the  air 
of  the  loft,  would  show  it  to  be  laden  with  suspended  dust 
particles.  Indeed  the  dust  is  distinctly  visible  in  the 
diffused  daylight.  Can  it  have  been  the  origin  of  the  ob- 
served life?  If  so,  are  we  not  bound  by  all  antecedent 
experience  to  regard  these  fruitful  particles  as  the  germs  of 
the  life  observed? 

The  name  of  Baron  Liebig  has  been  constantly  mixed  up 
with  these  discussions.  "We  have,"  it  is  said,  "his 
authority  for  assuming  that  dead  decaying  matter  can  pro- 
duce fermentation/'  True,  but  with  Liebig  fermentation 
was  by  no  means  synonymous  with  life.  It,  meant,  accord- 

*  An  actual  experiment  made  at  the  Bel  Alp  is  here  described. 


SPONTANEOUS  GENERATION.  577 

ing  to  him,  the  shaking  asunder  by  chemical  disturbance 
of  unstable  molecules.  Does  the  life  of  our  flasks,  then, 
proceed  from  dead  particles?  If  my  co-inquirer  should 
reply  "  Yes,"  then  I  would  ask  him,  "  What  warrant  does 
nature  offer  for  such  an  assumption?  Where,  amid  the 
multitude  of  vital  phenomena  in  which  her  operations  have 
been  clearly  traced,  is  the  slightest  countenance  given  to 
the  notion  that  the  sowing  of  dead  particles  can  produce  a 
living  crop?  "  With  regard  to  Baron  Liebig,  had  he  studied 
the  revelations  of  the  microscope  in  relation  to  these  ques- 
tions, a  mind  so  penetrating  could  never  have  missed  the 
significance  of  the  facts  revealed.  He,  however,  neglected 
the  microscope,  and  fell  into  error — but  not  into  error  so 
gross  as  that  in  support  of  which  his  authority  has  been  in- 
voked. Were  he  now  alive,  he  would,  I  doubt  not,  repudi- 
ate the  use  often  made  of  his  name — Liebig's  view  of  fer- 
mentation was  at  least  a  scientific  one,  founded  on  profound 
conceptions  of  molecular  instability.  But  this  view  by  no 
means  involves  the  notion  that  the  planting  of  dead  particles 
— "  Stickstoffsplittern  "as  Colin  contemptuously  calls  them 
— is  followed  by  the  sprouting  of  infusorial  life. 

Let  us  now  return  to  London  and  fix  our  attention  on 
the  dust  of  its  air.  Suppose  a  room  in  which  the  house- 
maid has  just  finished  her  work  to  be  completely  closed, 
with  the  exception  of  an  aperture  in  a  shutter  through 
which  a  sunbeam  enters  and  crosses  the  room.  The  float- 
ing dust  reveals  the  track  of  the  light.  Let  a  lens  be  placed 
in  the  aperture  to  condense  the  beam.  Its  parallel  rays  are 
now  converged  to  a  cone,  at  the  apex  of  which  the  dust  is 
raised  to  almost  unbroken  whiteness  by  the  intensity  of  its 
illumination.  Defended  from  all  glare,  the  eye  is  peculiarly 
sensitive  to  this  scattered  light.  The  floating  dust  of  Lon- 
don rooms  is  organic,  and  may  be  burned  without  leaving 
visible  residue.  The  action  of  a  spirit-lamp  flame  upon  the 
floating  matter  has  been  elsewhere  thus  described: 

In  a  cylindrical  beam  which  strongly  illuminated  the  dust  of  our 
laboratory,  I  placed  an  ignited  spirit-lamp.  Mingling  with  the  flame, 
and  round  its  rim,  were  seen  curious  wreaths  of  darkness  resembling 
an  intensely  black  smoke.  On  placing  the  flame  at  some  distance 
below  the  beam,  the  same  dark  masses  stormed  upward.  They 
were  blacker  than  the  blackest  smoke  ever  seen  issuing  from  the 
funnel  of  a  steamer;  and  their  resemblance  to  smoke  was  so  perfect 


578  FRAGMENTS  OF  SCIENCK. 

as  to  prompt  the  conclusion  that  the  apparently  pure  flame  of  the 
alcohol -lamp  required  but  a  beam  of  sufficient  intensity  to  reveal  its 
clouds  of  liberated  carbon. 

But  is  the  blackness  smoke?  This  question  presented  itself  in  a 
moment,  and  was  thus  answered:  A  red-hot  poker  was  placed  under- 
neath the  beam;  from  it  the  black  wreaths  also  ascended.  A  large 
hydrogen  flame,  which  emits  no  smoke,  was  next  employed,  and  it 
also  produced  with  augmented  copiousness  those  whirling  masses  of 
darkness.  Smoke  being  out  of  the  question,  what  is  the  blackness? 
It  is  simply  that  of  stellar  space;  that  is  to  say,  blackness  resulting 
from  the  absence  from  the  track  of  the  beam  of  all  matter  competent 
to  scatter  its  light.  When  the  flame  was  placed  below  the  beam,  the 
floating  matter  was  destroyed  in  situ,'  and  the  heated  air,  freed  from 
this  matter,  rose  into  the  beam,  jostled  aside  the  illuminated  particjes, 
and  substituted  for  their  light  the  darkness  due  to  its  own  perfect 
transparency.  Nothing  could  more  forcibly  illustrate  the  invisibility 
of  the  agent  which  renders  all  things  visible.  The  beam  crossed,  un- 
seen, the  black  chasm  formed  by  the  transparent  air,  while,  at  both 
sides  of  the  gap,  the  thick-strewn  particles  shone  out  like  a  luminous 
solid  under  the  powerful  illumination. 

Supposing  an  infusion  intrinsically  barren,  but  readily 
susceptible  of  putrefaction  when  exposed  to  common  air,  to 
be  brought  into  contact  with  this  unillurninable  air,  what 
would  be  the  result?  It  would  never  putrefy.  It  might, 
however,  be  urged  that  the  air  is  spoiled  by  its  violent  cal- 
cination. Oxygen  passed  through  a  spirit  lamp  flame  is, 
it  may  be  thought,  no  longer  the  oxygen  suitable  for  the 
development  and  maintenance  of  life.  We  have  an  easy 
escape  from  this  difficulty,  which  is  based,  however,  upon 
the  unproved  assumption  that  the  air  has  been  affected  by 
the  flame.  Let  a  condensed  beam  be  sent  through  a  large 
flask  or  bolthead  containing  common  air.  The  track  of  the 
beam  is  seen  within  the  flask — the  dust  revealing  the  light, 
and  the  light  revealing  the  dust.  Cork  the  flask,  stuff  its 
neck  with  cotton-wool,  or  simply  turn  it  mouth  downward 
and  leave  it  undisturbed  for  a  day  or  two.  Examined 
afterward  with  the  luminous  beam,  no  track  is  visible;  the 
light  passes  through  the  flask  as  though  a  vacuum.  The 
floating  matter  has  abolished  itself,  being  now  attached  to 
the  interior  surface  of  the  flask.  Were  it  our  object,  as  it 
will  be  subsequently,  to  effectually  detain  the  dirt,  we  might 
coat  that  surface  with  some  sticky  substance.  Here,  then, 
without  "  torturing"  the  air  in  any  way,  we  have  found 
a  means  of  ridding  it,  or  rather  of  enabling  it  to  rid  itself, 
of  floating  matter. 


SPONTANEOUS  GENERATION. 


579 


We  have  now  to  devise  a  means  of  testing  the  action  of 
such  spontaneously  purified  air  upon  putrescible  infusions. 
Wooden  chambers,  or  cases,  are  accordingly  constructed, 
having  glass  fronts,  side-windows,  and  back-doors. 
Through  the  bottoms  of  the  chambers  test-tubes  pass  air- 


tight; their  open  ends,  for  about  one-fifth  of  the  length  of 
the  tubes,  being  within  the  chambers.  Provision  is  made 
for  a  free  connection  through  sinuous  channels  between 
the  inner  and  the  outer  air.  Through  such  channels, 
though  open,  no  dust  will  reach  the  chamber.  The  top  of 
each  chamber  is  perforated  by  a  circular  hole  two  inches  in 
diameter,  closed  air-tight  by  a  sheet  of  india  rubber.  This 


580  FRAGMENTS  OF  SCIENCE. 

is  pierced  iu  the  middle  by  a  pin,  and  through  the  pin-hole 
is  pushed  the  shank  of  a  long  pipette,  ending  above  in  a 
small  funnel.  The  shank  also  passes  through  a  stuffing- 
box  of  cotton-wool  moistened  with  glycerine;  so  that, 
tightly  clasped  by  the  rubber  and  wool,  the  pipette  is  not 
likely  in  its  motions  up  and  down  to  carry  any  dust  into 
the  chamber.  The  annexed  woodcut  shows  a  chamber, 
with  six  test-tubes,  its  side-windows  w  w,  its  pipette  p  c, 
and  its  sinuous  channels  a  b  which  connect  the  air  of  the 
chamber  with  the  outer  air. 

The  chamber  is  carefully  closed  and  permitted  to  remain 
quiet  for  two  or  three  days.  Examined  at  the  beginning 
by  a  beam  sent  through  its  windows,  the  air  is  found  laden 
with  floating  matter,  which  in  three  days  has  wholly  dis- 
appeared. To  prevent  its  ever  rising  again,  the  internal 
surface  of  the  chamber  was  at  the  outset  coated  with 
glycerine.  The  fresh  but  putrescible  liquid  is  introduced 
into  the  six  tubes  in  succession  by  means  of  the  pipette. 
Permitted  to  remain  without  further  precaution,  every  one 
of  the  tubes  would  putrefy  and  fill  itself  with  life.  The 
liquid  has  been  in  contact  with  the  dust-laden  air  outside 
by  which  it  has  been  infected,  and  the  infection  must  be 
destroyed.  This  is  done  by  plunging  the  six  tubes  into  a 
bath  of  heated  oil  and  boiling  the  infusion.  The  time 
requisite  to  destroy  the  infection  depends  wholly  upon  its 
nature.  Two  minutes'  boiling  suffices  to  destroy  some 
contagia,  whereas  two  hundred  minutes'  boiling  fails  to 
destroy  others.  After  the  infusion  has  been  sterilized,  the 
oil-bath  is  withdrawn,  and  the  liquid,  whose  putrescibility 
has  been  in  no  way  affected  by  the  boiling,  is  abandoned  to 
the  air  of  the  chamber. 

With  such  chambers  I  tested,  in  the  autumn  and  winter 
of  1875-6,  infusions  of  the  most  various  kinds,  embracing 
natural  animal  liquids,  the  flesh  and  viscera1  of  domestic 
animals,  game,  fish  and  vegetables.  More  than  fifty 
chambers,  each  with  its  series  of  infusions,  were  tested, 
many  of  them  repeatedly.  There  was  no  shade  of  uncer- 
tainty in  any  of  the  results.  In  every  instance  we  had, 
within  the  chamber,  perfect  limpidity  and  sweetness,  which 
in  some  cases  lasted  for  more  than  a  year — without  the 
chamber,  with  the  same  infusion,  putridity  and  its  charac- 
teristic smells.  In  no  instance  was  the  least  countenance 
lent  to  the  notion  that  an  infusion  deprived  by  heat  of  its 


SPONTANEOUS  GENERATION.  581 

inherent  life,  and  placed  in  contact  with  air  cleansed  of  its 
visibly  suspended  matter,  has  any  power  to  generate  life 
anew. 

Remembering  then  the  number  and  variety  of  the  infu- 
sions employed,  and  the  strictness  of  our  adherence  to  the 
rules  of  preparation  laid  down  by  the  heterogenists  them- 
selves; remembering  that  we  have  operated  upon  the  very 
substances  recommended  by  them  as  capable  of  furnishing, 
even  in  untrained  hands,  easy  and  decisive  proofs  of  spon- 
taneous generation,  and  that  we  have  added  to  their  sub- 
stances many  others  of  our  own — if  this  pretended  gener- 
ative power  were  a  realitv,  surely  it  must  have  manifested 
itself  somewhere.  Speaking  roundly,  I  should  say  that  in 
such  closed  chambers  at  least  five  hundred  chances  have 
been  given  to  it,  but  it  has  nowhere  appeared. 

The  argument  is  now  to  be  clenched  by  an  experiment 
which  will  remove  every  residue  of  doubt  as  to  the  ability 
of  the  infusions  here  employed  to  sustain  life.  We  open 
the  back  doors  of  our  sealed  chambers,  and  permit  the 
common  air  with  its  floating  particles  to  have  access  to  our 
tubes.  For  three  months  they  have  remained  pellucid  and 
sweet — flesh,  fish,  and  vegetable  extracts  purer  than  ever 
cook  manufactured.  Three  days'  exposure  to  the  dusty 
air  suffices  to  render  them  muddy,  fetid,  and  swarming 
with  infusorial  life.  The  liquids  are  thus  proved,  one  and 
all,  ready  for  putrefaction  when  the  contaminating  agent 
is  applied.  I  invite  my  colleague  to  reflect  on  these  facts. 
How  will  he  account  for  the  absolute  immunity  of  a 
liquid  exposed  for  months  in  a  warm  room  to  optically 
pure  air,  and  its  infallible  putrefaction  in  a  few  days  when 
exposed  to  dust-laden  air?  He  must,  I  submit,  bow  to  the 
conclusion  that  the  dust-particles  are  the  cause  of  putre- 
factive life.  And  unless  he  accepts  the  hypothesis  that 
these  particles,  being  dead  in  the  air,  are  in  the  liquid 
miraculously  kindled  into  living  things,  he  must  conclude 
that  the  life  we  have  observed  springs  from  germs  or 
organisms  diffused  through  the  atmosphere. 

The  experiments  with  hermetically  sealed  flasks  have 
reached  the  number  of  940.  A  sample  group  of  130  of 
them  were  laid  before  the  Eoyal  Society  on  January  13, 
1876.  They  were  utterly  free  from  life,  having  been  com- 
pletely sterilized  by  three  minutes'  boiling.  Special  care 
had  been  taken  that  the  temperatures  to  which  the  flasks 


582  FRAGMENTS  OF  SCIENCE. 

were  exposed  should  include  those  previously  alleged  to  be 
efficient.  The  conditions  laid  down  by  the  heterogenist 
were  accurately  copied,  but  there  was  no  corroboration  of 
his  results.  Stress  was  then  laid  on  the  question  of  warmth, 
thirty  degrees  being  suddenly  added  to  the  temperatures 
with  which  both  of  us  had  previously  worked.  Waiving 
all  protest  against  the  caprice  thus  manifested,  I  met  this 
new  requirement  also.  The  sealed  tubes,  which  hud 
proved  barren  in  the  Koyal  Institution,  were  suspended  in 
perforated  boxes,  and  placed  under  the  supervision  of  an 
intelligent  assistant  in  the  Turkish  Bath  in  Jermyn  street. 
From  two  to  six  days  had  been  allowed  for  the  generation 
of  organisms  in  hermetically  sealed  tubes.  Mine  remained 
in  the  washing-room  of  the  bath  for  nine  days.  Ther- 
mometers placed  in  the  boxes,  and  read  off  twice  or  three 
times  a  day,  showed  the  temperature  to  vary  from  a  mini- 
mum of  101  degrees  to  a  maximum  of  112  degrees  Fahr. 
At  the  end  of  nine  days  the  infusions  were  as  clear  as  at 
the  beginning.  They  were  then  removed  to  a  warmer 
position.  A  temperature  of  115  degrees  had  been 
mentioned  as  particularly  favorable  to  spontaneous  gener- 
ation. For  fourteen  days  the  temperature  of  the  Turkish 
Bath  hovered  about  this  point,  falling  once  as  low  as  106 
degrees,  reaching  116  degrees  on  three  occasions,  118 
degrees  on  one,  and  119  degrees  on  two.  The  result  was 
quite  the  same  as  that  just  recorded.  The  higher 
temperatures  proved  perfectly  incompetent  to  develop 
life. 

Taking  the  actual  experiment  we  have  made  as  a  basis 
of  calculation,  if  our  940  flasks  were  opened  on  the  hayloft 
of  the  Bel  Alp,  858  of  them  would  become  filled  with 
organisms.  The  escape  of  the  remaining  82  strengthens 
our  case,  proving  as  it  does  conclusively  that  not  in  the  air, 
nor  in  the  infusions,  nor  in  anything  continuous  diffused 
through  the  air,  but  in  discrete  particles,  suspended  in  the 
air  and  nourished  by  the  infusions,  we  are  to  seek  the 
cause  of  life.  Our  experiment  proves  these  particles  to  be 
in  some  cases  so  far  apart  on  the  hayloft  as  to  permit  10 
per  cent,  of  our  flasks  to  take  in  air  without  contracting 
contamination.  A  quarter  of  a  century  ago  Pasteur  proved 
the  cause  of  "so-called  spontaneous  generation"  to  be 
discontinuous.  I  have  already  referred  to  his  observation 
that  12  out  of  20  flasks  opened  on  the  plains  escaped 


SPONTANEOUS  GENERATION.  583 

infection,  while  19  out  of  20  flasks  opened  on  the  Mer  de 
Glace  escaped.  Our  own  experiment  at  the  Bel  Alp  is  a 
more  emphatic  instance  of  the  same  kind,  90  per  cent,  of 
the  flasks  opened  in  the  hayloft  being  smitten,  while  not 
one  of  those  opened  on  the  free  mountain  ledge  was 
attacked. 

The  power  of  the  air  as  regards  putrefactive  infection  is 
incessantly  changing  through  natural  causes,  and  we  are 
able  to  alter  it  at  will.  Of  a  number  of  flasks  opened  in 
1876  in  the  laboratory  of  the  Koyal  Institution,  42  per 
cent,  were  smitten,  while  58  per  cent,  escaped.  In  1877 
the  proportion  in  the  same  laboratory  was  68  per  cent, 
smitten,  to  32  intact.  The  greater  mortality,  so  to  speak, 
of  the  infusions  in  1877  was  due  to  the  presence  of  hay 
which  diffused  its  germinal  dust  in  the  laboratory  air, 
causing  it  to  approximate  as  regards  infective  virulence  to 
the  air  of  the  Alpine  loft.  I  would  ask  my  friend  to 
bring  his  scientific  penetration  to  bear  upon  all  the 
foregoing  facts.  They  do  not  prove  spontaneous  genera- 
tion to  be  "impossible."  My  assertions,  however, 
relate  not  to  "  possibilities,"  but  to  proofs,  and  the  ex- 
periments just  described  do  most  distinctly  prove  the 
evidence' on  which  the  heterogenist  relies  to  be  written  on 
waste  paper. 

My  colleague  will  not,  I  am  persuaded,  dispute  these 
results;  but  he  may  be  disposed  to  urge  that  other  able 
and  honorable  men  working  at  the  same  subject  have 
arrived  at  conclusions  different  from  mine.  Most  freely 
granted;  but  let  me  here  recur  to  the  remarks  already 
made  in  speaking  of  the  experiments  of  Spallanzani,  to 
the  effect  that  the  failure  of  others  to  confirm  his  results 
by  no  means  upsets  their  evidence.  To  fix  the  ideas,  let 
us  suppose  that  my  colleague  comes  to  the  laboratory  of 
the  Koyal  Institution,  repeats  there  my  experiments,  and 
obtains  confirmatory  results;  arid  that  he  then  goes  to 
University  or  King's  College  where,  operating  with  the. 
same  infusions,  he  obtains  contradictory  results.  Will  he 
be  disposed  to  conclude  that  the  selfsame  substance  is 
barren  in  Albemarle  street  and  fruitful  in  Gower  street  or 
the  Strand?  His  Alpine  experience  has  already  made 
known  to  him  the  literally  infinite  differences  existing 
between  different  samples  of  air  as  regards  their  capacity 
for  putrefactive  infection.  And,  possessing  this  knowl- 


584  F&AGMKNTS  OP  SCIKNC& 

edge,  will  he  not  substitute  for  the  adventurous  conclusion 
thut  an  organic  infusion  is  barren  at  one  place  and  sponta- 
neously generative  at  another,  the  more  rational  and 
obvious  one  that  the  atmosphere  of  the  two  localities  which 
have  had  access  to  the  infusion  are  infective  in  different 
degrees? 

As  regards  workmanship,  moreover,  he  will  not  fail  to 
bear  in  mindj  that  fruitful-ness  may  be  due  to  errors  of 
manipulation,  while  barrenness  involves  the  presumption 
of  correct  experiment.  It  is  only  the  careful  worker  that 
can  secure  the  latter,  while  it  is  open  to  every  novice 
to  obtain  the  former.  Barrenness  is  the  result  at  which 
the  conscientious  experimenter,  whatever  his  theoretic 
convictions  may  be,  ought  to  aim,  omitting  no  pains 
to  secure  it,  and  resorting  only  when  there  is  no  escape 
from  it  to  the  conclusion  that  the  life  observed  comes 
from  no  source  which  correct  experiment  could  neutralize 
or  avoid. 

Let  us  again  take  a  definite  case.  Supposing  my 
colleague  to  operate  with  the  same  apparent  care  on  100 
infusions — or  rather  on  100  samples  of  the  same  infusion 
— and  that  50  of  them  prove  fruitful  and  50  barren. 
Are  we  to  say  that  the  evidence  for  and  against  lieterogeny 
is  equally  balanced?  There  are  some  who  would  not  only 
say  this,  but  who  would  treasure  up  the  50  fruitful  flasks 
as  "positive"  results,  and  lower  the  evidential  value  of 
the  50  barren  flasks  by  labeling  them  "  negative"  results. 
This,  as  shown  by  Dr.  William  Eoberts,  is  an  exact  in- 
version of  the  true  order  of  the  terms  positive  and  nega- 
tive.* Not  such,  I  trust,  would  be  the  course  pursued  by 
my  friend.  As  regards  the  50  fruitful  flasks  he  would,  I 
doubt  not,  repeat  the  experiment  with  redoubled  care  and 
scrutiny,  and  not  by  one  repetition  only,  but  by  many, 
assure  himself  that  he  had  not  fallen  into  error.  Such 
faithful  scrutiny  fully  carried  out  would  infallibly  lead  him. 
to  the  conclusion  that  here,  as  in  all  other  cases,  the 
evidence  in  favor  of  spontaneous  generation  crumbles  in 
the  grasp  of  the  competent  inquirer. 

The  botanist  knows  that  different  seeds  possess  different 
powers  of  resistance  to  heat.f  Some  are  killed  by  a 

*  See  his  truly  philosophical  remarks  on  this  head  in  the  "  British 
Medical  Journal,"  1876,  p.  282. 

f  I  am  indebted  to  Dr.  Thiselton  Dyer  for  various  illustrations  of 
such  differences.  It  is,  however,  surprising  that  a  subject  of  such. 


SPONTANEOUS  GENEHATION.  585 

momentary  exposure  to  the  boiling  temperature,"  while 
others  withstand  it  for  several  hours.  Most  of  our  ordinary 
seeds  are  rapidly  killed,  while  Pouchet  made  known  to  the 
Paris  Academy  of  Sciences  in  1866,  that  certain  seeds, 
which  had  been  transported  in  fleeces  of  wool  from  Brazil, 
germinated  after  four  hours'  boiling.  The  germs  of  the 
air  vary  as  much  among  themselves  as  the  seeds  of  the 
botanist.  In  some  localities  the  diffused  germs  are  so  tender 
that  boiling  for  five  minutes,  or  even  less,  would  be  sure  to 
destroy  them  all;  in  other  localities  the  diffused  germs  are 
so  obstinate,  that  many  hours'  boiling  would  be  requisite  to 
deprive  them  of  their  power  of  germination.  The  absence 
or  presence  of  a  truss  of  desiccated  hay  would  produce 
differences  as  great  as  those  here  described.  The  greatest 
endurance  that  I  have  ever  observed — and  I  believe  it  is  the 
greatest  on  record — was  a  case  of  survival  after  eight  hours' 
boiling. 

As  regards  their  power  of  resisting  heat,  the  infusorial 
germs  of  our  atmosphere  might  be  classified  under  the  fol- 
lowing and  intermediate  heads:  Killed  in  five  minutes;  not 
killed  in  five  minutes  but  killed  in  fifteen;  not  killed  in 
fifteen  minutes  but  killed  in  thirty;  not  killed  in  thirty 
minutes  but  killed  in  an  hour;  not  killed  in  an  hour  but 
killed  in  two  hours;  not  killed  in  two  but  killed  in  three 
hours;  not  killed  in  three  but  killed  in  four  hours.  I  have 
had  several  cases  of  survival  after  four  and  five  hours'  boil- 
ing, some  survivals  after  six,  and  one  after  eight  hours' 
boiling.  Thus  far  has  experiment  actually  reached;  but 
there  is  no  valid  warrant  for  fixing  upon  even  eight  hours 
as  the  extreme  limit  of  vital  resistance.  Probably  more 
extended  researches  (though  mine  have  been  very  extensive) 
would  reveal  germs  more  obstinate  still.  It  is  also  certain 
that  we  might  begin  earlier,  and  find  germs  which  are 
destroyed  by  a  temperature  far  below  that  of  boiling  water. 
In  the  presence  of  such  facts,  to  speak  of  a  death-point  of 
bacteria  and  their  germs  would  be  unmeaning — but  of 
this  more  anon. 

"What  present  warrant/' it  has  been  asked,  "is  there 
for  supposing  that  a  naked,  or  almost  naked,  speck  of 

high  scientific  importance  should  not  have  been  more  thoroughly 
explored.  Here  the  scoundrels  who  deal  in  killed  seeds  might  be 
able  to  add  to  our  knowledge. 


586  FRAGMENTS 

protoplasm  can  withstand  four,  six,  or  eight  hours'  boil- 
ing? "  Regarding  naked  specks  of  protoplasm  I  make  no 
assertion.  I  know  nothing  about  them,  save  as  the  crea- 
tures of  fancy.  Bnt  I  do  affirm,  not  as  a  "  supposition,"  nor 
an  "assumption/7  nor  a  "probable  guess,"  nor  as  "a  wild 
hypothesis,"  but  as  a  matter  of  the  most  undoubted  fact, 
that  the  spores  of  the  hay  bacillus,  when  thoroughly  desic- 
cated by  age,  have  withstood  the  ordeal  mentioned.  And 
I  further  affirm  that  these  obdurate  germs,  under  the 
guidance  of  the  knowledge  that  they  are  germs,  can  be 
destroyed  by  five  minutes'  boiling,  or  even  less.  This 
needs  explanation.  The  finished  bacterium  perishes  at  a 
temperature  far  below  that  of  boiling  water,  and  it  is  fair 
to  assume  that  the  nearer  the  germ  is  to  its  final  sensitive 
condition  the  more  readily  will  it  succumb  to  heat.  Seeds 
soften  before  and  during  germination.  This  premised,  the 
simple  description  of  the  following  process  will  suffice  to 
make  its  meaning  understood. 

An  infusion  infected  with  the  most  powerfully  resisteut 
germs,  but  otherwise  protected  against  the  floating  matters 
of  the  air,  is  gradually  raised  to  its  boiling-point.  Such 
germs  as  have  reached  the  soft  and  plastic  state  immediately 
preceding  their  development  into  bacteria  are  thus 
destroyed.  The  infusion  is  then  put  aside  in  a  warm  room 
for  ten  or  twelve  hours.  If  for  twenty-four,  we  might  have 
the  liquid  charged  with  well-developed  bacteria.  To  antici- 
pate this,  at  the  end  of  ten  or  twelve  hours  we  raise  the  in- 
fusion a  second  time  to  the  boiling  temperature,  which,  as 
before,  destroys  all  germs  then  approaching  their  point  of 
final  development.  The  infusion  is  again  put  aside  for  ten 
or  twelve  hours,  and  the  process  of  heating  is  repeated. 
We  thus  kill  the  germs  in  the  order  of  their  resistance, 
and  finally  kill  the  last  of  them.  No  infusion  can  with- 
stand this  process  if  it  be  repeated  a  sufficient  number  of 
times.  Artichoke,  cucumber,  and  turnip  infusions,  which 
had  proved  specially  obstinate  when  infected  with  the 
germs  of  desiccated  hay,  were  completely  broken  down  by 
this  method  of  discontinuous  heating,  three  minutes  being 
found  sufficient  to  accomplish  what  three  hundred  minutes' 
continuous  boiling  failed  to  accomplish.  I  applied  the 
method,  moreover,  to  infusions  of  various  kinds  of  hay,  in- 
cluding those  most  tenacious  of  life.  Not  one  of  them  bore 
the  ordeal.  These  results  were  clearly  foreseen  before  they 


SPONTANEOUS  GKNERATlON.  587 

were  realized,  so  that  the  germ  theory  fulfills  the  test  of 
every  true  theory,  that  test  being  the  power  of  prevision. 

When  "naked  or  almost  naked  specks  of  protoplasm  " 
are  spoken  of,  the  imagination  is  drawn  upon,  not  the 
objective  truth  of  Nature.  Such  words  sound  like  the 
words  of  knowledge  where  knowledge  is  really  nil.  The 
possibility  of  a  "  thin  covering  "  is  conceded  by  those  who 
speak  in  this  way.  Such  a  covering  may,  however,  exer- 
cise a  powerful  protective  influence.  A  thin  pellicle  of 
india-rubber,  for  example,  surrounding  a  pea  keeps  it 
hard  in  boiling  water  for  a  time  sufficient  to  reduce  an  un- 
covered pea  to  pulp.  The  pellicle  prevents  imbibition, 
diffusion,  and  the  consequent  disintegration.  A  greasy  or 
oily  surface,  or  even  the  layer  of  air  which  clings  to  certain 
bodies,  would  act  to  some  extent  in  a  similar  way.  "  The 
singular  resistance  of  green  vegetables  to  sterilization," 
says  Dr.  William  Eoberts,  "  appears  to  be  due  to  some 
peculiarity  of  the  surface,  perhaps  their  smooth  glistening 
epidermis  which  prevented  complete  wetting  of  their  sur- 
faces." I  pointed  out  in  1876  that  the  process  by  which  an 
atmospheric  germ  is  wetted  would  be  an  interesting  sub- 
ject of  investigation.  A  dry  microscope  covering-glass  may 
be  caused  to  float  on  water  for  a  year.  A  sewing-needle 
may  be  similarly  kept  floating,  though  its  specific  gravity 
is  nearly  eight  times  that  of  water.  Were  it  not  for  some 
specific  relation  between  the  matter  of  the  gerrn  and  that 
of  the  liquid  into  which  it  falls,  wetting  would  be  simply 
impossible.  Antecedent  to  all  development  there  must  be 
an  interchange  of  matter  between  the  germ  and  its  environ- 
ment; and  this  interchange  must  obviously  depend  upon 
the  relation  of  the  germ  to  its  encompassing  liquid.  Any- 
thing that  hinders  this  interchange  retards  the  destruction 
of 'the  germ  in  boiling  water.  In  my  paper  published  in 
the  "Philosophical  Transactions"  for  1877,  I  add  the 
following  remark: 

It  is  not  difficult  to  see  that  the  surface  of  a  seed  or  germ  may  be 
so  affected  by  desiccation  and  other  causes  as  practically  to  prevent 
contact  between  it  and  the  surrounding  liquid.  The  body  of  a  germ, 
moreover,  may  be  so  indurated  by  time  and  dryness  as  to  resist 
powerfully  the  insinuation  of  water  between  its  constituent  mole- 
cules. It  would  be  difficult  to  cause  such  a  germ  to  imbibe  the 
moisture  necessary  to  produce  the  swelling  and  softening  which 
precede  its  destruction  in  a  liquid  of  high  temperature. 


&8g  FRAGMENTS  Of  SCIKNCB. 

However  this  may  be— whatever  be  the  state  of  the  sur- 
face of  the  body,  of  the  spores  of  Bacillus  subtilis,  they 
do  as  a  matter  of  certainty  resist,  under  some  circum- 
stances, exposure  for  hours  to  the  heat  of  boiling  water. 
No  theoretic  skepticism  can  successfully  stand  in  the  wa 
of  this  fact,  established  as  it  has  been  by  hundreds,  if  not 
thousands,  of  rigidly  conducted  experiments. 

We  have  now  to  test  one  of  the  principal  foundations  of 
the  doctrine  of  spontaneous  generation  as  formulated  in 
this  country.  With  this  view,  I  place  before  my  friend 
and  co-inquirer  two  liquids  which  have  been  kept  for  six 
months  in  one  of  our  sealed  chambers,  exposed  to  optically 
pure  air.  The  one  is  a  mineral  solution  containing  in 
proper  proportions  all  the  substances  which  enter  into  the 
composition  of  bacteria,  the  other  is  an  infusion  of  turnip 
— it  might  be  any  one  of  a  hundred  other  infusions, 
animal  or  vegetable.  Both  liquids  are  as  clear  as  distilled 
water,  and  there  is  no  trace  of  life  in  either  of  them. 
They  are,  in  fact,  completely  sterilized.  A  rnutton-chop, 
over  which  a  little  water  has  been  poured  to  keep  its  juices 
from  drying  up,  has  lain  for  three  days  upon  a  plate  in  our 
warm  room.  It  smells  offensively.  Placing  a  drop  of  the 
fetid  mutton-juice  under  a  microscope,  it  is  found  swarm- 
ing with  the  bacteria  of  putrefaction.  With  a  speck  of 
the  swarming  liquid  I  inoculate  the  clear  mineral  solution 
and  the  clear  turnip  infusion,  as  a  surgeon  might  inoculate 
an  infant  with  vaccine  lymph.  In  four-and-twenty  hours 
the  transparent  liquids  have  become  turbid  through- 
out, and  instead  of  being  barren  as  at  first  they  are 
teeming  with  life.  The  experiment  may  be  repeated  a 
thousand  times  with  the  same  invariable  result.  To  the 
naked  eye  the  liquids  at  the  beginning  were  alike,  being 
both  equally  transparent — to  the  naked  eye  they  are  alike 
at  the  end,  being  both  equally  muddy.  Instead  of  putrid 
mutton-juice,  we  might  take  as  a  source  of  infection  any 
one  of  a  hundred  other  putrid  liquids,  animal  or  vegetable. 
So  long  as  the  liquid  contains  living  bacteria  a  speck  of  it 
communicated  either  to  the  clear  mineral  solution,  or  to 
the  clear  turnip  infusion,  produces  in  twenty-four  hours 
the  effect  here  described. 

We  now  vary  the  experiment  thus:  Opening  the  back- 
door of  another  closed  chamber  which  has  contained  for 


SPONTANEOUS  GENERATION.  589 

months  the  pure  mineral  solution  and  the  pure  turnip 
infusion  side  by  side,  I  drop  into  each  of  them  a  small 
pinch  of  laboratory  dust.  The  effect  here  is  tardier  than 
when  the  speck  of  putrid  liquid  was  employed.  In  three 
days,  however,  after  its  infection  with  the  dust,  the  turnip 
infusion  is  muddy,  and  swarming  as  before  with  bacteria. 
But  what  about  the  mineral  solution  which,  in  our  first 
experiment,  behaved  in  a  manner  undistinguishable  from 
the  turnip-juice?  At  the  end  of  three  days  there  is  not  a 
bacterium  to  be  found  in  it.  At  the  end  of  three  weeks  it 
is  equally  innocent  of  bacterial  life.  We  may  repeat  the 
experiment  with  the  solution  and  the  infusion  a  hundred 
times  with  the  same  invariable  result.  Always  in  the  case 
of  the  latter  the  sowing  of  the  atmospheric  dust  yields  a 
crop  of  bacteria"— never  in  the  former  does  the  dry  germinal 
matter  kindle  into  active  life.*  What  is  the  inference 
which  the  reflecting  mind  must  draw  from  this  experi- 
ment? Is  it  not  as  clear  as  day  that  while  both  liquids  are 
able  to  feed  the  bacteria  and  to  enable  them  to  increase 
and  multiply,  after  they  have  been  once  fully  developed, 
only  one  of  the  liquids  is  able  to  develop  into  active 
bacteria  the  germinal  dust  of  the  air? 

I  invite  my  friend  to  reflect  upon  this  conclusion;  he 
will,  I  think,  see  that  there  is  no  escape  from  it.  He  may, 
if  he  prefers,  hold  the  opinion,  which  I  consider  erroneous, 
that  bacteria  exist  in  the  air,  not  as  germs  but  as  desiccated 
organisms.  The  inference  remains,  that  while  the  one 
liquid  is  able  to  force  the  passage  from  the  inactive  to  the 
active  state,  the  other  is  not. 

But  this  is  not  at  all  the  inference  which  has  been  drawn 
from  experiments  with  the  mineral  solution.  Seeing  its 
ability  to  nourish  bacteria  when  once  inoculated  with  the 
living  active  organism,  and  observing  that  no  bacteria 
appeared  in  the  solution  after  long  exposure  to  the  air,  the 
inference  was  drawn  that  neither  bacteria  nor  their  germs 
existed  in  the  air.  Throughout  Germany  the  ablest 
literature  of  the  subject,  even  that  opposed  to  heterogeny, 
is  infected  with  this  error;  while  heterogenists  at  home 

*  This  is  the  deportment  of  the  mineral  solution  as  described  by 
others.  My  own  experiments  would  lead  me  to  say  that  the  develop- 
ment of  the  bacteria,  though  exceedingly  slow  and  difficult,  is,  uot 
impossible. 


590  FRAGMENTS  OF  SCIENCE. 

and  abroad  have  based  upon  it  a  triumphant  demonstration 
of  their  doctrine.  It  is  proved,  they  say,  by  the  deport- 
ment of  the  mineral  solution  that  neither  bacteria  nor 
their  germs  exist  in  the  air;  hence,  if,  on  exposing  a 
thoroughly  sterilized  turnip  infusion  to  the  air,  bacteria 
appear,  they  must  of  necessity  have  been  spontaneously 
generated.  In  the  words  of  Dr.  Bastian:  "  We  can  only 
infer  that  while  the  boiled  saline  solution  is  quite  incapable 
of  engendering  bacteria,  such  organisms  are  able  to  arise 
de  novo  in  tlie  boiled  organic  infusion."  * 

I  would  ask  my  eminent  colleague  what  he  thinks  of 
this  reasoning  now?  The  datum  is — '•'  A  mineral  solution 
exposed  to  common  air  does  not  develop  bacteria;"  the 
inference  is — "  Therefore  if  a  turnip  infusion  similarly 
exposed  develop  bacteria,  they  must  be  spontaneously 
generated."  The  inference,  on  the  face  of  it,  is  an 
unwarranted  one.  But  while  as  matter  of  logic  it  is  incon- 
clusive, as  matter  of  fact  it  is  chimerical.  London  air  is 
as  surely  charged  with  the  germs  of  bacteria  as  London 
chimneys  are  with  smoke.  The  inference  just  referred  to 
is  completely  disposed  of  by  the  simple  question:  "  Why, 
when  your  sterilized  organic  infusion  is  exposed  to  optically 
pure  air,  should  this  generation  of  life  de  novo  utterly 
cease?  Why  should  I  be  able  to  preserve  my  turnip-juice 
side  by  side  with  your  saline  solution  for  the  three  hundred 
and  sixty-five  days  of  the  year,  in  free  connection  with  the 
general  atmosphere,  on  the  sole  condition  that  the  portion 
of  that  atmosphere  in  contact  with  the  juice  shall  be 
visibly  free  from  floating  dust,  while  three  days'  exposure 
to  that  dust  fills  it  with  bacteria?"  Am  I  over  sanguine 
in  hoping  that  as  regards  the  argument  here  set  forth  he 
who  runs  may  read,  and  he  who  reads  may  understand? 

We  now  proceed  to  the  calm  and  thorough  consideration 
of  another  subject,  more  important  if  possible  than  the 
foregoing  one,  but  like  it  somewhat  difficult  to  seize  by 
reason  of  the  very  opulence  of  the  phraseology,  logical  and 
rhetorical,  in  which  it  has  been  set  forth.  The  subject 
now  to  be  considered  relates  to  what  has  been  called  "  the 
death-point  of  bacteria."  Those  who  happen  to  be 
acquainted  with  the  modern  English  literature  of  the 
question  will  remember  how  challenge  after  challenge  has 

*"  Proceedings  of  the  Royal  Society,"  vol.  xxi.,  p.  130. 


SPONTANEOUS  GKNERATION.  591 

been  issued  to  panspermutists  in  general,  and  to  one  or 
two  home  workers  in  particular,  to  come  to  close  quarters 
on  this  cardinal  point.  It  is  obviously  the  stronghold  of 
the  English  heterogenist.  "  Water/'  he  says,  "  is  boiling 
merrily  over  a  fire  when  some  luckless  person  upsets  the 
vessel  so  that  the  heated  fluid  exercises  its  scathing 
influence  upon  an  uncovered  portion  of  the  body — hand, 
arm,  or  face.  Here,  at  all  events,  there  is  no  room  for 
doubt.  Boiling  water  unquestionably  exercises  a  most 
pernicious  and  rapidly  destructive  effect  upon  the  living 
matter  of  which  we  are  composed."*  And  lest  it  should 
be  supposed  that  it  is  the  high  organization  which,  in  this 
case,  renders  the  body  susceptible  to  heat,  he  refers  to  the 
action  of  boiling  water  on  the  hen's  egg  to  dissipate  the 
notion.  "  The  conclusion,"  he  says,  "  would  seem  to 
force  itself  upon  us  that  there  is  something  intrinsically 
deleterious  in  the  action  of  boiling  water  upon  living  mat- 
ter— whether  this  matter  be  of  high  or  of  low  organiza- 
tion." f  Again,  at  another  place:  "  It  has  been  shown  that 
the  briefest  exposure  to  the  influence  of  boiling  water  is 
destructive  of  all  living  matter."  J 

The  experiments  already  recorded  plainly  show  that 
there  is  a  marked  difference  between  the  dry  bacterial 
matter  of  the  air,  and  the  wet,  soft,  and  active  bacteria  of 
putrefying  organic  liquids.  The  one  can  be  luxuriantly 
bred  in  the  saline  solution,  the  others  refuse  to  be  born 
there,  while  both  of  them  are  copiously  developed  in  a 
sterilized  turnip  infusion.  Inferences,  as  we  have  already 
seen,  founded  on  the  deportment  of  the  one  liquid  cannot 
with  the  warrant  of  scientific  logic  be  extended  to  the 
other.  But  this  is  exactly  what  the  heterogenist  has  done, 
thus  repeating  as  regards  the  death-point  of  bacteria  the 
error  into  which  he  fell  concerning  the  germs  of  the  air. 
Let  us  boil  our  muddy  mineral  solution  with  its  swarming 
bacteria  for  five  minutes.  In  the  soft  succulent  condition 
in  which  they  exist  in  the  solution  not  one  of  them  escapes 
destruction.  The  same  is  true  of  the  turnip  infusion 
if  it  be  inoculated  with  the  living  bacteria  only — the 
aerial  dust  being  carefully  excluded.  In  both  cases  the 

*Bastian,  "  Evolution,"  p.  133. 
\Jbid.,  p.  135, 
ilbid.,  p.  46. 


592  FRAGMENTS  OP  SCIENCE. 

dead  organisms  sink  to  the  bottom  of  the  liquid,  and 
without  re-inoculation  no  fresh  organisms  will  arise. 
But  the  case  is  entirely  different  when  we  inoculate  our 
turnip  infusion  with  the  desiccated  germinal  matter  afloat 
in  the  air. 

The  "death-point"  of  bacteria  is  the  maximum  tem- 
perature at  which  they  can  live,  or  the  minimum  tempera- 
ture at  which  they  cease  to  live.  If,  for  example  they 
survive  a  temperature  of  140  degrees,  and  do  not  survive  a 
temperature  of  150  degrees,  the  death-point  lies  somewhere 
between  these  two  temperatures.  Vaccine  lymph,  for 
example,  is  proved  by  Messrs.  Braid  wood  and  Vacher  to 
be  deprived  of  its  power  of  infection  by  brief  exposure  to  a 
temperature  between  140  and  150  degrees  Fahr.  This 
may  be  regarded  as  the  death-point  of  the  lymph,  or 
rather  of  the  particles  diffused  in  the  lymph,  which  con- 
stitute the  real  coutagium.  If  no  time,  however,  be  named 
for  the  application  of  the  heat,  the  term  "death-point"  is 
a  vague  one.  An  infusion,  for  example,  which  will  resist 
five  hours'  continuous  exposure  to  the  boiling  tempevature, 
will  succumb  to  five  days'  exposure  to  a  temperature  50 
degrees  Fahr.  below  that  of  boiling.  The  fully  developed 
soft  bacteria  of  putrefying  liquids  are  not  only  killed  by 
five  minutes'  boiling,  but  by  less  than  a  single  minute's 
boiling — indeed,  they  are  slain  at  about  the  same  temper- 
ature as  the  vaccine.  The  same  is  true  of  the  plastic, 
active  bacteria  of  the  turnip  infusion.* 

But,  instead  of  choosing  a  putrefying  liquid  for  inocula- 
tion, let  us  prepare  and  employ  our  inoculating  substance 
in  the  following  simple  way:  Let  a  small  wisp  of  hay, 
desiccated  by  age,  be  washed  in  a  glass  of  water,  and  let  a 
perfectly  sterilized  turnip  infusion  be  inoculated  with  the 
washing  liquid.  After  three  hours'  continuous  boiling  the 
infusion  thus  infected  will  often  develop  luxuriant  bacte- 
rial life.  Precisely  the  same  occurs  if  a  turnip  infusion  be 
prepared  in  an  atmosphere  well  charged  with  desiccated 

*In  my  paper  in  the  "Philosophical  Transactions "  for  1876,  I 
pointed  out  and  illustrated  experimentally  the  difference,  as  regards 
rapidity  of  development,  between  water  germs  and  air-germs;  the 
growth  from  the  already  softened  water-germs  proving  to  be  practi- 
cally as  rapid  as  from  developed  bacteria.  This  preparedness  of  the 
germ  for  rapid  development  is  associated  with  its  preparedness  for 
rapid  destruction. 


SPONTANEOUS  GENERATION.  593 

hay-germs.  The  infusion  in  this  case  infects  itself  with- 
out special  inoculation,  and  its  subsequent  resistance  to 
sterilization  is  often  very  great.  On  the  1st  of  March  last 
I  purposely  infected  the  air  of  our  laboratory  with  the 
germinal  dust  of  a  sapless  kind  of  hay  mown  in  1875. 
Ten  groups  of  flasks  were  charged  with  turnip  infusion 
prepared  in  the  infected  laboratory,  and  were  afterward 
subjected  to  the  boiling  temperature  for  periods  varying 
from  15  minutes  to  240  minutes.  Out  of  the  ten  groups 
only  one  was  sterilized — that,  namely,  which  had  been 
boiled  for  four  hours.  Every  flask  of  the  nine  groups 
which  had  been  boiled  for  15,  30,  45,  60,  75,  90,  105,  120, 
and  180  minutes  respectively,  bred  organisms  afterward. 
The  same  is  true  of  other  vegetable  infusions.  On  the 
28th  of  February  last,  for  example,  I  boiled  six  flasks, 
containing  cucumber  infusion  prepared  in  an  infected 
atmosphere,  for  periods  of  15,  30,  45,  60,  120,  and  180 
minutes.  Every  flask  of  the  group  subsequently  developed 
organisms.  On  the  same  day,  in  the  case  of  three  flasks, 
the  boiling  was  prolonged  to  240,  300,  and  360  minutes; 
and  these  three  flasks  were  completely  sterilized.  Animal 
infusions,  which  under  ordinary  circumstances  are  rendered 
infallibly  barren  by  five  minutes'  boiling,  behave  like  the 
vegetable  infusions  in  an  atmosphere  infected  with  hay- 
germs.  On  the  30th  of  March,  for  example,  five  flasks 
were  charged  with  a  clear  infusion  of  beef  and  boiled  for  60 
minutes,  120  minutes,  180  minutes,  240  minutes,  and  300 
minutes,  respectively.  Every  one  of  them  became  subse- 
quently crowded  with  organisms,  and  the  same  happened 
to  a  perfectly  pellucid  mutton  infusion  prepared  at  the 
same  time.  The  cases  are  to  be  numbered  by  hundreds  in 
which  similar  powers  of  resistance  were  manifested  by 
infusions  of  the  most  diverse  kinds. 

In  the  presence  of  such  facts  I  would  ask  my  colleague 
whether  it  is  necessary  to  dwell  for  a  single  instant  on  the 
one-sidedness  of  the  evidence  which  led  to  the  conclusion 
that  all  living  matter  has  its  life  destroyed  by  "  the  briefest 
exposure  to  the  influence  of  boiling  water."  An  infusion 
proved  to  be  barren  by  six  months'  exposure  to  moteless 
air  maintained  at  a  temperature  of  90  degrees  Fahr.,  when 
inoculated  with  full-grown  active  bacteria,  fills  itself  in 
two  days  with  organisms  so  sensitive  as  to  be  killed  by  a 
few  minutes'  exposure  to  a  temperature  much  below  that 


594  F&A  GMENTS  OF  SCIENCE. 

of  boiling  water.  But  the  extension  of  this  result  to  the 
desiccated  germinal  mutter  of  the  air  is  without  warrantor 
justification.  This  is  obvious  without  going  beyond  the 
argument  itself.  But  we  have  gone  far  beyond  the  argu- 
ment, and  proved  by  multiplied  experiment  the  alleged 
destruction  of  all  living  matter  by  the  briefest  exposure  to 
the  influence  of  boiling  water  to  be  a  delusion.  The  whole 
logical  edifice  raised  upon  this  basis  falls  therefore  to  the 
ground;  and  the  argument  that  bacteria  and  their  germs, 
being  destroyed  at  140  degrees,  must,  if  they  appear  after 
exposure  to  212  degrees,  be  spontaneously  generated,  is,  I 
trust,  silenced  forever. 

Through  the  precautions,  variations,  and  repetitions 
observed  and  executed  with  the  view  of  rendering  its  re- 
sults secure,  the  separate  vessels  employed  in  this  inquiry 
have  mounted  up  in  two  years  to  nearly  ten  thousand. 

Besides  the  philosophic  interest  attaching  to  the  problem 
of  life's  origin,  which  will  be  always  immense,  there  are  the 
practical  interests  involved  in  the  application  of  the  doc- 
trines here  discussed  to  surgery  and  medicine.  The 
antiseptic  system,  at  which  I  have  already  glanced,  illus- 
trates the  manner  in  which  beneficent  results  of  the  grav- 
est moment  follow  in  the  wake  of  clear  theoretic  insight. 
Surgery  was  once  a  noble  art;  it  is  now,  as  well,  a  noble 
science.  Prior  to  the  introduction  of  the  antiseptic  system, 
the  thoughtful  surgeon  could  not  have  failed  to  learn  empir- 
ically that  there  was  something  in  the  air  which  often 
defeated  the  most  consummate  operative  skill.  That  some- 
thing the  antiseptic  treatment  destroys  or  renders  innocuous. 
At  King's  College  Mr.  Lister  operates  and  dresses  while  a 
fine  shower  of  mixed  carbolic  acid  and  water,  produced  in 
the  simplest  manner,  falls  upon  the  wound,  the  lint  and 
gauze  employed  in  the  subsequent  dressing  being  duly 
saturated  with  the  antiseptic.  At  St.  Bartholomew's  Mr. 
Callender  employs  the  dilute  carbolic  acid  without  the 
spray;  but,  as  regards  the  real  point  aimed  at — the  pre- 
venting of  the  wound  from  becoming  a  nidus  for  the  prop- 
agation of  septic  bacteria — the  practice  in  both  hospitals 
is  the  same.  Commending  itself  as  it  does  to  the  scien- 
tifically trained  mind,  the  antiseptic  system  has  struck  deep 
root  in  Germany. 

Had  space  allowed,  it  would  have  given  me  pleasure  to 
point  out  the  present  position  of  the  "  germ  theory "  in 


SPONTANEOUS  GENERATION.  595 

reference  to  the  phenomena  of  infectious  disease,  distin- 
guishing arguments  based  on  analogy — which,  however,  are 
terribly  strong — from  those  based  on  actual  observation.  I 
should  have  liked  to  follow  up  the  account  I  have  already 
given*  of  the  truly  excellent  researches  of  a  young  and  an 
unknown  German  physician  named  Koch,  on  splenic  fever, 
by  an  account  of  what  Pasteur  has  recently  done  with 
reference  to  the  same  subject.  Here  we  have  before  us  a 
living  contagium  of  the  most  deadly  power,  which  we  can 
follow  from  the  beginning  to  the  end  of  its  life  cycle,  f 
We  find  it  in  the  blood  or  spleen  of  a  smitten  animal  in 
the  state  say  of  short,  motionless  rods.  When  these  rods 
are  placed  in  a  nutritive  liquid  on  the  warm  stage  of  the 
microscope,  we  soon  see  them  lengthening  into  filaments 
which  lie,  in  some  cases,  side  by  side,  forming  in  others 
graceful  loops,  or  becoming  coiled  into  knots  of  a  com- 
plexity not  to  be  unraveled.  We  finally  see  those  filaments 
resolving  themselves  into  innumerable  spores,  each  with 
death  potentially  housed  within  it,  yet  not  to  be  distin- 
guished microscopically  from  the  harmless  germs  of  Bacillus 
subtilis,  The  bacterium  of  splenic  fever  is  called  Bacillus 
anthracis.  This  formidable  organism  was  shown  to  me  by 
M.  Pasteur  in  Paris  last  July.  His  recent  investigations 
regarding  the  part  it  plays  pathologically  certainly  rank 
among  the  most  remarkable  labors  of  that  remarkable 
man.  Observer  after  observer  had  strayed  and  fallen 
in  this  laud  of  pitfalls,  a  multitude  of  opposing  conclu- 
sions and  mutually  destructive  theories  being  the 
result.  In  association  with  a  younger  physiological 
colleague,  M.  Joubert,  Pasteur  struck  in  amid  the 
chaos,  and  soon  reduced  it  to  harmony.  They  proved, 
among  other  things,  that  in  cases  where  previous  observers 
in  France  had  supposed  themselves  to  be  dealing  solely 
with  splenic  fever,  another  equally  virulent  factor  was 
simultaneously  active.  Splenic  fever  was  often  over- 
mastered by  septicaemia,  and  results  due  solely  to  the  latter 
had  been  frequently  made  the  ground  of  pathological  in- 
ferences regarding  the  character  and  cause  of  the  former. 

*  "Fortnightly  Review,"  November,  1876,  see  article  "Fermenta- 
tion " 

f  Dallinger  and  Drysdale  bad  previously  sbown  wbat  skill  and 
patience  can  accomplish,  by  tbeir  admirable  observations  on  the  life 
history  of  the  monads. 


596  FRAGMENTS  OF  SCIENCE. 

Combining  duly  the  two  factors,  all  the  previous  irregu- 
larities disappeared,  every  result  obtained  receiving  the 
fullest  explanation.  On  studying  the  account  of  this 
masterly  investigation,  the  words  wherewith  Pasteur  him- 
self feelingly  alludes  to  the  difficulties  and  dangers  of  the 
experimenter's  art  came  home  to  rne  with  especial  force: 
"  J'ai  tant  de  fois  eprouve  que  dans  cet  art  difficile  de 
1'experimentation  les  plus  habiles  brouchent  a  chaque  pas, 
et  que  1'interpretation  des  faits  n'est  pas  moms  peril- 
leuse."  * 


CHAPTER  XXXVI. 

SCIENCE    AND    MAN.f 

A  MAGNET  attracts  iron;  but  when  we  analyze  the 
effect  we  learn  that  the  metal  is  not  only  attracted  but 
repelled,  the  final  sipproach  to  the  magnei  being  due  to 
the  difference  of  two  unequal  and  opposing  forces.  Social 
progress  is  for  the  most  part  typified  by  this  duplex  or 
polar  action.  As  a  general  rule,  every  advance  is  balanced 
by  a  partial  retreat,  every  amelioration  is  associated  more 
or  less  with  deterioration.  No  great  mechanical  improve- 
ment, for  example,  is  introduced  for  the  benefit  of  society 
at  large  that  does  not  bear  hardly  upon  individuals. 
Science,  like  other  things,  is  subject  to  the  operation  of 
this  polar  law,  what  is  good  for  it  under  one  aspect  being 
bad  for  it  under  another. 

Science  demands  above  all  things  personal  concentration. 
Its  home  is  the  study  of  the  mathematician,  the  quiet 
laboratory  of  the  experimenter,  and  the  cabinet  of  the 
meditative  observer  of  nature.  Different  atmospheres  are 
required  by  the  man  of  science,  as  such,  and  the  man  of 
action.  Thus  the  facilities  of  social  and  international 
intercourse,  the  railway,  the  telegraph,  and  the  post  office, 
which  are  such  undoubted  boons  to  the  man  of  action, 
react  to  some  extent  injuriously  on  the  man  of  science. 
Their  tendency  is  to  break  up  that  concentrativeness  which, 
as  I  have  said,  is  an  absolute  necessity  to  the  scientific 
investigator. 

*  "  Comptes-Rendus,"  Ixxxiii.,  p.  177. 

f  Presidential  Address,  delivered  before  the  Birmingham  and  Mid- 
land Institute,  October  1,  1877;  with  additions. 


SCIENCE  AND  MAN.  597 

The  men  who  have  most  profoundly  influenced  the 
world  from  the  scientific  side  have  habitually  sought 
isolation.  Faraday,  at  a  certain  period  of  his  career, 
formally  renounced  dining  out.  Darwin  lives  apart  from 
the  bustle  of  the  world  in  his  quiet  home  in  Kent.  Mayer 
and  Joule  dealt  in  unobtrusive  retirement  with  the 
weightiest  scientific  questions.  There  is,  however,  one 
motive  power  in  the  world  which  no  man,  be  he  a  scientific 
student  or  otherwise,  can  afford  to  treat  with  indifference; 
and  that  is,  the  cultivation  of  right  relations  with  his 
fellow-men — the  performance  of  his  duty,  not  as  an  isolated 
individual,  but  as  a  member  of  society.  It  is  duty  in  this 
aspect,  overcoming  alike  the  sense  of  possible  danger  and 
the  desire  for  repose,  that  has  placed  me  in  your  presence 
here  to-night. 

To  look  at  his  picture  as  a  whole,  a  painter  requires 
distance;  and  to  judge  of  the  total  scientific  achievement 
of  any  age,  the  standpoint  of  a  succeeding  age  is  desirable. 
We  may,  however,  transport  ourselves  in  idea  into  the 
future,  and  thus  survey  with  more  or  less  completeness  the 
science  of  our  time.  We  sometimes  hear  it  decried,  and 
contrasted  to  its  disadvantage  with  the  science  of  other 
times.  I  do  not  think  that  this  will  be  the  verdict  of 
posterity.  I  think,  on  the  contrary,  that  posterity  will 
acknowledge  that  in  the  history  of  science  no  higher 
samples  of  intellectual  conquest  are  recorded  than  those 
which  this  age  has  made  its  own.  One  of  the  most  salient 
of  these  I  propose,  with  your  permission,  to  make  the 
subject  of  our  consideration  during  the  coming  hour. 

It  is  now  generally  admitted  that  the  man  of  to-day  is 
the  child  and  product  of  incalculable  antecedent  time. 
His  physical  and  intellectual  textures  have  been  woven  for 
him  during  his  passage  through  phases  of  history  and 
forms  of  existence  which  lead  the  mind  back  to  an  abysmal 
past.  One  of  the  qualities  which  he  has  derived  from  that 
past  is  the  yearning  to  let  in  the  light  of  principles  on  the 
otherwise  bewildering  flux  of  phenomena.  He  has  been 
described  by  the  German  Lichtenberg  as  "das  rastlose 
Ursacheuthier  " — the  restless  cause- seeking  animal — in 
whom  facts  excite  a  kind  of  hunger  to  know  the  sources 
from  which  they  spring.  Never,  I  venture  to  say,  in  the 
history  of  the  world  has  this  longing  been  more  liberally 
responded  to,  both  among  men  of  science  aud  the  general 


598  FR  A  GMENTS  0  F  SCIENCE. 

public,  than  during  the  last  thirty  or  forty  years.  I  say 
"the  general  public,"  because  it  is  a  feature  of  our  time 
that  the  man  of  science  no  longer  limits  his  labors  to  the 
society  of  his  colleagues  and  his  peers,  but  shares,  as  far  as 
it  is  possible  to  share,  with  the  world  at  large  the  fruits  of 
inquiry. 

The  celebrated  Robert  Boyle  regarded  the  universe  as  a 
machine;  Mr.  Carlyle  prefers  regarding  it  as  a  tree.  He 
loves  the  image  of  the  umbrageous  Jgdrasil  better  than 
that  of  the  Strasburg  clock.  A  machine  may  be  defined 
as  an  organism  with  life  and  direction  outside;  a  tree  may 
be  defined  as  an  organism  with  life  and  direction  within. 
In  the  light  of  these  definitions,  I  close  with  the  conception 
of  Carlyle.  The  order  and  energy  of  the  universe  I  hold 
to  be  inherent,  and  not  imposed  from  without,  the  expres- 
sion of  fixed  law  and  not  of  arbitrary  will,  exercised  by 
what  Carlyle  would  call  an  Almighty  Clockmaker.  But 
the  two  conceptions  are  not  so  much  opposed  to  each  other 
after  all.  In  one  fundamental  particular  they  at  all  events 
agree.  They  equally  imply  the  interdependence  and. 
harmonious  interaction  of  parts,  and  the  subordination  of 
the  individual  powers  of  the  universal  organism  to  the 
working  of  the  whole. 

Never  were  the  harmony  and  interdependence  just 
referred  to  so  clearly  recognized  as  now.  Our  insight 
regarding  them  is  not  that  vague  and  general  insight  to 
which  our  fathers  had  attained,  and  which,  in  early  times, 
was  more  frequently  affirmed  by  the  synthetic  poet  than  by 
the  scientific  man.  The  interdependence  of  our  day  has 
become  quantitative — expressible  by  numbers — leading,  it 
must  be  added,  directly  into  that  inexorable  reign  of  law 
which  so  many  gentle  people  regard  with  dread.  In  the 
domain  now  under  review  men  of  science  had  first  to  work 
their  way  from  darkness  into  twilight,  and  from  twilight 
into  day.  There  is  no  solution  of  continuity  in  science.  It  is 
not  given  to  any  man,  however  endowed,  to  rise  spontane- 
ously into  intellectual  splendor  without  the  parentage  of 
antecedent  thought.  Great  discoveries  grow.  Here,  as  in 
other  cases,  we  have  first  the  seed,  then  the  ear,  then  the 
full  corn  in  the  ear,  the  last  member  of  the  series  implying 
the  first.  Thus,  as  regards  the  discovery  of  gravitation 
with  which  the  name  of  Newton  is  identified,  notions  more 
or  less  clear  concerning  it  had  entered  many  minds  before 


SCIENCE  AND  MAN.  599 

Newton's  transcendent  mathematical  genius  raised  it  to 
the  level  of  a  demonstration.  The  whole  of  his  deductions, 
moreover,  rested  upon  the  inductions  of  Kepler.  Newton 
shot  beyond  his  predecessors;  but  his  thoughts  were  rooted 
in  their  thoughts,  and  a  just  distribution  of  merit  would 
assign  to  them  a  fair  portion  of  the  honor  of  discovery. 

Scientific  theories  sometimes  float  like  rumors  iu  the 
air  before  they  receive  complete  expression.  The  doom 
of  a  doctrine  is  often  practically  sealed,  and  the  truth  of 
one  is  often  practically  accepted,  long  prior  to  the  demon- 
stration of  either  the  error  or  the  truth.  Perpetual  motion 
was  discarded  before  it  was  proved  to  be  opposed  to  natural 
law;  and,  as  regards  the  connection  and  interaction  of 
natural  forces,  intimations  of  modern  discoveries  are  strewn 
through  the  writings  of  Leibnitz,  Boyle,  Hooke,  Locke 
and  others. 

Confining  ourselves  to  recent  times,  Dr.  Ingleby  has 
pointed  out  to  me  some  singularly  sagacious  remarks  bear- 
ing upon  this  question,  which  were  published  by  an 
anonymous  writer  in  1820.  Roget's  penetration  was  con- 
spicuous in  1829.  Mohr  had  grasped  in  1837  some  deep- 
lying  truth.  The  writings  of  Faiaday  furnish  frequent 
illustrations  of  his  profound  belief  in  the  unity  of  nature. 
"  1  have  long/'  he  writes  in  1845,  "  held  an  opinion  almost 
amounting  to  conviction,  in  common,  I  believe,  with  other 
lovers  of  natural  knowledge,  that  the  various  forms  under 
which  the  forces  of  matter  are  made  manifest  have  one 
common  origin,  or,  in  other  words,  are  so  directly  related 
and  mutually  dependent,  that  they  are  convertible,  as  it 
were,  one  into  another,  and  possess  equivalence  of  power 
in  their  action."  His  own  researches  on  magneto-elec- 
tricity, on  electro-chemistry,  and  on  the  "magnetization 
of  light/'  led  him  directly  to  this  belief.  At  an  early  date 
Mr.  Justice  Grove  made  his  mark  upon  this  question. 
Colding,  though  starting  from  a  metaphysical  basis,  grasped 
eventually  the  relation  between  heat  and  mechanical 
work,  and  sought  to  determine  it  experimentally.  And 
here  let  me  say,  that  to  him  who  has  only  the  truth  at 
heart,  and  who  in  his  dealings  with  scientific  history  keeps 
his  soul  unwarped  by  envy,  hatred,  or  malice,  personal  or 
national,  every  fresh  accession  to  historic  knowledge  must 
be  welcome.  For  every  newcomer  of  proved  merit,  more 
especially  if  that  merit  should  have  been  previously  over- 


600  FRAGMENTS  OF  SCIENCE. 

looked,  he  makes  ready  room  in  his  recognition  or  his 
reverence.  But  no  retrospect  of  scientific  literature  has  as 
yet  brought  to  light  a  claim  which  can  sensihly  affect  the 
positions  accorded  to  two  great  Path-hewers,  as  the 
Germans  call  them,  whose  names  in  relation  to  this  subject 
are  linked  in  indissoluble  association.  These  names  are 
Julius  Robert  Mayer  and  James  Prescott  Joule. 

In  his  essay  on  "  Circles"  Mr.  Emerson,  if  I  remember 
rightly,  pictured  intellectual  progress  as  rhythmic.  At  a 
given  moment  knowledge  is  surrounded  by  a  barrier  which 
marks  its  limit.  It  gradually  gathers  clearness  and 
strength  until  by  and  by  some  thinker  of  exceptional  power 
bursts  the  barrier  and  wins  a  wider  circle,  within  which 
thought  once  more  entrenches  itself.  I3ut  the  internal 
force  again  accumulates,  the  new  barrier  is  in  its  turn 
broken,  and  the  mind  finds  itself  surrounded  by  a  still 
wider  horizon.  Thus,  according  to  Emerson,  knowledge 
spreads  by  intermittent  victories  instead  of  progressing  at 
a  uniform  rate. 

When  Dr.  Joule  first  proved  that  a  weight  of  one  pound, 
falling  through  a  height  of  seven  hundred  and  seventy-two 
feet,  generated  an  amount  of  heat  competent  to  warm  a 
pound  of  water  one  degree  Fahrenheit,  and  that  in  lifting 
the  weight  so  much  heat  exactly  disappeared,  he  broke  an 
Emersonian  "  circle,"  releasing  by  the  act  an  amount  of 
scientific  energy  which  rapidly  overran  a  vast  domain,  and 
embodied  itself  in  the  great  doctrine  known  as  the  "  Con- 
servation of  Energy."  This  doctrine  recognizes  in  the 
material  universe  a  constant  sum  of  power  made  up  of 
items  among  which  the  most  Protean  fluctuations  are 
incessantly  going  on.  It  is  as  if  the  body  of  Nature  were 
alive,  the  thrill  and  interchange  of  its  energies  resembling 
those  of  an  organism.  The  parts  of  the  "  stupendous 
whole"  shift  and  change,  augment  and  diminish,  appear  and 
disappear,  while  the  total  of  which  they  are  the  parts 
remains  quantitatively  immutable.  Immutable,  because 
when  change  occurs  it  is  always  polar — plus  accompanies 
minus,  gain  accompanies  loss,  no  item  varying  in  the 
slightest  degree  withqj.it  an  absolutely  equal  change  of 
some  other  item  in  the  opposite  direction. 

The  sun  warms  the  tropical  ocean,  converting  a  portion 
of  its  liquid  into  vapor,  which  rises  in  the  air  and  is 
recoudeused  on  mountain  heights,  returning  in  rivers  to 


SC1KNCE  AND  MAN.  601 

the  ocean  from  which  it  came.  Up  to  the  point  where 
condensation  begins,  an  amount  of  heat  exactly  equivalent 
to  the  molecular  work  of  vaporization  and  the  mechanical 
work  of  lifting  the  vapor  to  the  mountain-tops  has  disap- 
peared from  the  universe.  What  is  the  gain  corresponding 
to  this  loss?  It  will  seem  when  mentioned  to  be  expressed 
in  a  foreign  currency.  The  loss  is  a  loss  of  heat;  the  gain 
is  a  gain  of  distance,  both  as  regards  masses  and  molecules 
Water  which  was  formerly  at  the  sea-level  has  been  lifted 
to  a  position  from  which  it  can  fall;  molecules  which  have 
been  locked  together  as  a  liquid  are  now  separate  as  vapor 
which  can  recompense.  After  condensation  gravity  comes 
into  effectual  play,  pulling  the  showers  down  upon  the 
hills,  and  the  rivers  thus  created  through  their  gorges  to 
the  sea.  Every  raindrop  which  smites  the  mountain  pro- 
duces its  definite  amount  of  heat;  every  river  in  its  course 
develops  heat  by  the  clash  of  its  cataracts  and  the  friction 
of  its  bed.  In  the  act  of  condensation,  moreover,  the 
molecular  work  of  vaporization  is  accurately  reversed. 
Compare,  then,  the  primitive  loss  of  solar  warmth  with 
the  heat  generated  by  the  condensation  of  the  vapor,  and 
by  the  subsequent  fall  of  the  water  from  cloud  to  sea. 
They  are  mathematically  equal  to  each  other.  No  particle 
of  vapor  was  formed  and  lifted  without  being  paid  for  in 
the  currency  of  solar  heat;  no  particle  returns  as  water  to 
the  sea  without  the  exact  quantitative  restitution  of  that 
heat.  There  is  nothing  gratuitous  in  physical  nature,  no 
expenditure  without  equivalent  gain,  no  gain  without 
equivalent  expenditure.  With  inexorable  constancy  the 
one  accompanies  the  other,  leaving  no  nook  or  crevice 
between  them  for  spontaneity  to  mingle  with  the  pure  and 
necessary  play  of  natural  force.  Has  this  uniformity  of 
nature  ever  been  broken?  The  reply  is:  "Not  to  the 
knowledge  of  science." 

What  has  been  here  stated  regarding  heat  and  gravity 
applies  to  the  whole  of  inorganic  nature.  Let  us  take  an 
illustration  from  chemistry.  The  metal  zinc  may  be  burned 
in  oxygen,  a  perfectly  definite  amount  of  heat  being  pro- 
duced by  the  combustion  of  a  given  weight  of  the  metal. 
But  zinc  may  also  be  burned  in  a  liquid  which  contains  a 
supply  of  oxygen — in  water,  for  example.  It  does  not  in 
this  case  produce  flame  or  tire,  but  it  does  produce  heat 
which  is  capable  of  accurate  measurement.  But  the  heat 


602  FRAGMENTS  OF  SCIENCE. 

of  zinc  burned  in  water  falls  short  of  that  produced  in  pure 
oxygen,  the  reason  being  that  to  obtain  its  oxygen  from 
the  water  the  zinc  must  first  dislodge  the  hydrogen.  It 
is  in  the  performance  of  this  molecular  work  that  the 
missing  heat  is  absorbed.  Mix  the  liberated  hydrogen 
with  oxygen  and  cause  them  to  recombine;  the  heat 
developed  is  mathematically  equal  to  the  missing  heat. 
Thus  in  pulling  the  oxygen  and  hydrogen  asunder  an 
amount  of  heat  is  consumed  which  is  accurately  restored 
by  their  reunion. 

This  leads  up  to  a  few  remarks  upon  the  voltaic 
battery.  It  is  not  my  design  to  dwell  upon  the  technical 
features  of  this  wonderful  instrument,  but  simply,  by 
means  of  it,  to  show  what  varying  shapes  a  given  amount 
of  energy  can  assume  while  maintaining  unvarying  quanti- 
tative stability.  When  that  form  of  power  which  we  call 
an  electric  current  passes  through  Grove's  battery,  zinc  is 
consumed  in  acidulated  water;  and  in  the  battery  we  are 
able  so  to  arrange  matters  that  when  no  current  passes  no 
zinc  shall  be  consumed.  Now  the  current,  whatever  it 
may  be,  possesses  the  power  of  generating  heat  outside  the 
battery.  We  can  fuse  witli  it  iridium,  the  most  refractory 
of  metals,  or  we  can  produce  with  it  the  dazzling  electric 
light,  and  that  at  any  terrestrial  distance  from  the  battery 
itself. 

We  will  now,  however,  content  ourselves  with  causing 
the  current  to  raise  a  given  length  of  platinum  wire,  first 
to  a  blood-heat,  then  to  redness,  and  finally  to  a  white 
heat.  The  heat  under  these  circumstances  generated  in 
the  battery  by  the  combustion  of  a  fixed  quantity  of  zinc 
is  no  longer  constant,  but  it  varies  inversely  as  the  heat 
generated  outside.  If  the  outside  heat  be  nil,  the  inside 
heat  is  a  maximum;  if  the  external  wire  be  raised  to  a 
blood-heat,  the  internal  heat  falls  slightly  short  of  the 
maximum.  If  the  wire  be  rendered  red-hot,  the  quantity 
of  missing  heat  within  the  battery  is  greater,  and  if  the 
external  wire  be  rendered  white-hot,  the  defect  is  greater 
still.  Add  together  the  internal  and  external  heat  pro- 
duced by  the  combustion  of  a  given  weight  of  zinc,  and 
you  have  an  absolutely  constant  total.  The  heat  generated 
without  is  so  much  lost  within,  the  heat  generated  within 
is  so  much  lost  without,  the  polar  changes  already  adverted 
to  coming  here  conspicuously  into  play.  Thus  ill  a  variety 


SCIENCE  AND  MAN.  603 

of  ways  we  can  distribute  the  itemsof  a  never-  varying  sum, 
but  even  the  subtle  agency  of  the  electric  current  places  no 
creative  power  in  our  hands. 

Instead  of  generating  external  heat,  we  may  cause  the 
current  to  effect  chemical  decomposition  at  a  distance 
from  the  battery.  Let  it,  for  example,  decompose  water 
into  oxygen  and  hydrogen.  The  heat  generated  in  the 
battery  under  these  circumstances  by  the  combustion  of  a 
given  weight  of  zinc  falls  short  of  what  is  produced  when 
there  is  no  decomposition.  How  far  short?  The  question 
admits  of  a  perfectly  exact  answer.  When  the  oxygen  and 
hydrogen  recombine,  the  heat  absorbed  in  the  decomposi- 
tion is  accurately  restored,  and  it  is  exactly  equal  in  amount 
to  that  missing  in  the  battery.  We  may,  if  we  like,  bottle 
up  the  gases,  carry  in  this  form  the  heat  of  the  battery  to 
the  polar  regions,  and  liberate  it  there.  The  battery,  in 
fact,  is  a  hearth  on  which  fuel  is  consumed;  but  the  heat 
of  the  combustion,  instead  of  being  confined  in  the  usual 
manner  to  the  hearth  itself,  may  be  first  liberated  at  the 
other  side  of  the  world. 

And  here  we  are  able  to  solve  an  enigma  which  long 
perplexed  scientific  men,  and  which  could  not  be  solved 
until  the  bearing  of  the  mechanical  theory  of  heat  upon 
the  phenomena  of  the  voltaic  battery  was  understood. 
The  puzzle  was,  that  a  single  cell  could  not  decompose 
water.  The  reason  is  now  plain  enough.  The  solution 
of  an  equivalent  of  zinc  in  a  single  cell  develops  not 
much  more  than  half  the  amount  of  heat  required  to 
decompose  an  equivalent  of  water,  and  the  single  cell 
cannot  cede  an  amount  of  force  which  it  does  not  possess. 
But  by  forming  a  battery  of  two  cells  instead  of  one, 
we  develop  an  amount  of  heat  slightly  in  excess  of  that 
needed  for  the  decomposition  of  the  water.  The  two- 
celled  battery  is  therefore  rich  enough  to  pay  for  that  de- 
composition, and  to  maintain  the  excess  referred  to  within 
its  own  cells. 

Similar  reflections  apply  to  the  thermo-electric  pile,  an 
instrument  usually  composed  of  small  bars  of  bismuth  and 
antimony  soldered  alternately  together.  The  electric  cur- 
rent is  here  evoked  by  warming  the  soldered  junctions  of 
one  face  of  the  pile.  Like  the  voltaic  current,  the  thermo- 
electric current  can  heat  wires,  produce  decomposition, 
magnetize  iron,  and  deflect  a  magnetic  needle  at  any  dis.- 


604  FRAGMENTS  OF  SCIENCE. 

tance  from  its  origin.  You  will  be  disposed,  and  rightly 
disposed,  to  refer  those  distant  manifestations  of  power  to 
the  heat  communicated  to  the  face  of  the  pile,  but  the 
case  is  worthy  of  closer  examination.  In  1826  Thomas 
Seebeck  discovered  thermo-electricity,  and  six  years  sub- 
sequently Peltier  made  an  observation  which  comes  with 
singular  felicity  to  onr  aid  in  determining  the  material 
used  up  in  the  formation  of  the  thermo-electric  current. 
He  found  that  when  a  weak  extraneous  current  was  sent 
from  antimony  to  bismuth  the  junction  of  the  two  metals 
was  always  heated,  but  that  when  the  direction  was  from 
bismuth  to  antimony  the  junction  was  chilled.  Now  the 
current  in  the  thermo-pile  itself  is  always  from  bismuth  to 
antimony,  across  the  heated  junction — a  direction  in  which 
it  cannot  possibly  establish  itself  without  consuming  the 
heat  imparted  to  the  junction.  This  heat  is  the  nutriment 
of  the  current.  Thus  the  heat  generated  by  the  thermo- 
current  in  a  distant  wire  is  simply  that  originally  imparted 
to  the  pile,  which  has  been  first  transmuted  into  electricity, 
and  then  retransmuted  into  its  first  format  a  distance  from 
its  origin.  As  water  in  a  state  of  vapor  passes  from  a  boiler 
to  a  distant  condenser,  and  there  assumes  its  primitive 
form  without  gain  or  loss,  so  the  heat  communicated  to 
the  therrno-pile  distills  into  the  subtler  electric  current, 
which  is,  as  it  were,  recondensed  into  heat  in  the  distant 
platinum  wire. 

In  my  youth  I  thought  an  electro-magnetic  engine  which 
was  shown  to  me  a  veritable  perpetual  motion — a  machine, 
that  is  to  say,  which  performed  work  without  the  ex- 
penditure of  power.  Let  us  consider  the  action  of  such  a 
machine.  Suppose  it  to  be  employed  to  pump  water  from 
a  lower  to  a  higher  level.  On  examining  the  battery  which 
works  the  engine  we  find  that  the  zinc  consumed  does  not 
yield  its  full  amount  of  heat.  The  quantity  of  heat  thus 
missing  within  is  the  exact  thermal  equivalent  of  the 
mechanical  work  performed  without.  Let  the  water  fall 
again  to  the  lower  level;  it  is  warmed  by  the  fall.  Add 
the  heat  thus  produced  to  that  generated  by  the  friction, 
mechanical  and  magnetical,  of  the  engine;  we  thus  obtain 
the  precise  amount  of  heat  missing  in  the  battery.  All  the 
effects  obtained  from  the  machine  are  thus  strictly  paid 
for;  this  "  payment  for  results  "  being,  I  would  repeat,  the 
inexorable  method  of  nature. 


BCIENCE  AND  MAN.  605 

No  engine,  however  subtly  devised,  can  evade  this  law  of 
equivalence,  or  perform  on  its  own  account  the  smallest 
modicum  of  work.  The  machine  distributes,  but  it  cannot 
create.  Is  the  animal  body,  then,  to  be  classed  among 
machines?  When  I  lift  a  weight,  or  throw  a  stone,  or 
climb  a  mountain,  or  wrestle  with  my  comrade,  am  I  not 
conscious  of  actually  creating  and  expending  force?  Let 
us  look  at  the  antecedents  of  this  force.  We  derive  the 
muscle  and  fat  of  our  bodies  from  what  we  eat.  Animal 
heat  you  know  to  be  due  to  the  slow  combustion  of  this 
fuel.  My  arm  is  now  inactive,  and  the  ordinary  slow 
combustion  of  my  blood  and  tissue  is  going  on.  For  every 
grain  of  fuel  thus  burned  a  perfectly  definite  amount  of  heat 
has  been  produced.  I  now  contract  my  biceps  muscle 
without  causing  it  to  perform  external  work.  The  com- 
bustion is  quickened,  and  the  heat  is  increased;  this 
additional  heat  being  liberated  in  the  muscle  itself.  I  lay 
hold  of  a  56-lb.  weight,  and  by  the  contraction  of  rny  biceps 
lift  it  through  the  vertical  space  of  a  foot.  The  blood  and 
tissue  consumed  during  this  contraction  have  not  developed 
in  the.  muscle  their  due  amount  of  heat.  A  quantity  of 
heat  is  at  this  moment  missing  in  my  muscle  which  would 
raise  the  temperature  of  an  ounce  of  water  somewhat  more 
than  one  degree  Fahrenheit.  I  liberate  the  weight:  it 
falls  to  the  earth,  and  by  its  collision  generates  the 
precise  amount  of  heat  missing  in  the  muscle.  My  mus- 
cular heat  is  thus  transferred  from  its  local  hearth  to 
external  space.  The  fuel  is  consumed  in  my  body,  but  the 
heat  of  combustion  is  produced  outside  my  body.  The 
case  is  substantially  the  same  as  that  of  the  voltaic  battery 
when  it  performs  external  work,  or  produces  external  heat. 
All  this  points  to  the  conclusion  that  the  force  we  employ 
in  muscular  exertion  is  the  force  of  burning  fuel  and  not 
of  creative  will.  In  the  light  of  these  facts  the  body  is 
seen  to  be  as  incapable  of  generating  energy  without 
expenditure,  as  the  solids  and  liquids  of  the  voltaic  bat- 
tery. The  body,  in  other  words,  falls  into  the  category  of 
machines. 

We  can  do  with  the  body  all  that  we  have  already  done 
with  the  battery — heat  platinum  wires,  decompose  water, 
magnetize  iron,  and  deflect  a  magnetic  needle.  The  com- 
bustion of  muscle  may  be  made  to  produce  all  these  effects, 
as  the  combustion  of  zinc  may  be  caused  to  produce  them. 


606  FRAGMENTS  OP  SCTENCW. 

By  turning  the  handle  of  a  magneto-electric  machine  a 
coil  of  wire  may  be  caused  to  rotate  between  the  poles  of  a 
magnet.  As  long  as  the  two  ends  of  the  coil  are  uncon- 
nected we  have  simply  to  overcome  the  ordinary  inertia  and 
friction  of  the  machine  in  turning  the  handle.  But  the 
moment  the  two  ends  of  the  coil  are  united  by  a  thin 
platinum  wire  a  sudden  addition  of  labor  is  thrown  upon 
the  turning  arm.  When  the  necessary  labor  is  expended, 
its  equivalent  immediately  appears.  The  platinum  wire 
glows.  You  can  readily  maintain  it  at  a  white  heat,  or 
even  fuse  it.  This  is  a  very  remarkable  result.  From  the 
muscles  of  the  arm,  with  a  temperature  of  100  degrees,  we 
extract  the  temperature  of  molten  platinum,  which  is 
nearly  four  thousand  degrees.  The  miracle  here  is  the 
reverse  of  that  of  the  burning  bush  mentioned  in  Exodus. 
There  the  bush  burned,  but  was  not  consumed:  here  the 
body  is  consumed,  but  does  not  burn.  The  similarity  of 
the  action  with  that  of  the  voltaic  battery  when  it  heats 
an  external  wire  is  too  obvious  to  need  pointing  out. 
When  the  machine  is  used  to  decompose  water,  the  heat  of 
the  muscle,  like  that  of  the  battery,  is  consumed  in  molec- 
ular work,  being  fully  restored  when  the  gases  recombine. 
As  before,  also,  the  transmuted  heat  of  the  muscles  may 
be  bottled  up,  carried  to  the  polar  regions,  and  there 
restored  to  its  pristine  form. 

The  matter  of  the  human  body  is  the  same  as  that  of  the 
world  around  us;  and  here  we  find  the  forces  of  the  human 
body  identical  with  those  of  inorganic  nature.  Just  as 
little  as  the  voltaic  battery  is  the  animal  body  a  creator  of 
force.  It  is  an  apparatus  exquisite  and  effectual  beyond  all 
others  in  transforming  and  distributing  the  energy  with 
which  it  is  supplied,  but  it  possesses  no  creative  power. 
Compared  with  the  notions  previously  entertained  regard- 
ing the  play  of  "  vital  force "  this  is  a  great  result.  The 
problem  of  vital  dynamics  has  been  described  by  a  com- 
petent authority  as  "the  grandest  of  all."  I  subscribe  to 
this  opinion,  and  honor  correspondingly  the  man  who  first 
successfully  grappled  with  the  problem.  He  was  no  pope, 
in  the  sense  of  being  infallible,  but  he  was  a  man  of  genius 
whose  work  will  be  held  in  honor  as  long  as  science 
endures.  I  have  already  named  him  in  connection  with 
our  illustrious  countryman  Dr.  Joule.  Other  eminent 


SCIENCE  AND  MAN.  607 

men  took  up  this  subject  subsequently  and  independently, 
but  all  that  has  been  done  hitherto"  enhances  instead  of 
diminishing  the  merits  of  Dr.  Mayer. 

Consider  the  vigor  of  his  reasoning.  "Beyond  the 
power  of  generating  internal  heat,  the  animal  organism 
can  generate  heat  external  to  itself.  A  blacksmith  by 
hammering  can  warm  a  nail,  and  a  savage  by  friction  can 
heat  wood  to  its  point  of  ignition.  Unless,  then,  we 
abandon  the  physiological  axiom  that  the  animal  body 
cannot  create  heat  out  of  nothing,  we  are  driven  to  the 
conclusion  that  it  is  the  total  heat,  within  and  without, 
that  ought  to  be  regarded  as  the  real  calorific  effect  of  the 
oxidation  within  the  body."  Mayer,  however,  not  only 
states  the  principle,  but  illustrates  numerically  the  transfer 
of  muscular  heat  to  external  space.  A  bowler  who  imparts 
a  velocity  of  30  feet  to  an  8-lb.  ball  consumes  in  the  act 
one-tenth  of  a  grain  of  carbon.  The  heat  of  the  muscle  is 
here  distributed  over  the  track  of  the  ball,  being  developed 
there  by  mechanical  friction.  A  man  weighing  150  Ibs. 
consumes  in  lifting  his  own  body  to  a  height  of  8  feet  the 
heat  of  a  grain  of  carbon.  Jumping  from  this  height  the 
heat  is  restored.  The  consumption  of  %  oz.  4  drs.  20  grs. 
of  carbon  would  place  the  same  man  on  the  summit  of  a 
mountain  10,000  feet  high.  In  descending  the  mountain 
an  amount  of  heat  equal  to  that  produced  by  the  com- 
bustion of  the  foregoing  amount  of  carbon  is  restored. 
The  muscles  of  a  laborer  whose  weight  is  150  Ibs.  weigh  64 
Ibs.  When  dried  they  are  reduced  to  15  Ibs.  Were  the 
oxidation  corresponding  to  a  day-laborer's  ordinary  work 
exerted  on  the  muscles  alone,  they  would  be  wholly  con- 
sumed in  80  days.  Were  the  oxidation  necessary  to  sustain 
the  heart's  action  concentrated  on  the  heart  itself,  it  would 
be  consumed  in  8  days.  And  if  we  confine  our  attention 
to  the  two  ventricles,  their  action  would  consume  the 
associated  muscular  tissue  in  3£  days.  With  a  fullness  and 
precision  of  which  this  is  but  a  sample  did  Mayer,  between 
1842  and  1845,  deal  with  the  great  question  of  vital 
dynamics. 

In  direct  opposition,  moreover,  to  the  foremost  scientific 
authorities  of  that  day,  with  Liebig  at  their  head,  this 
solitary  Heilbronn  worker  was  led  by  his  calculations  to 
maintain  that  the  muscles,  in  the  main,  played  the  part  of 
machinery,  converting  the  fat,  which  had  been  previously 


608  v      FRAGMENTS  or 

considered  a  mere  heat-producer,  into  the  motive  power  of 
the  organism.  Mayer's  prevision  has  been  justified  by 
events,  for  the  scientific  world  is  now  upon  his  side. 

We  place,  then,  food  in  our  stomachs  as  so  much  com- 
bustible matter.  It  is  first  dissolved  by  purely  chemical 
processes,  and  the  nutritive  fluid  is  poured  into  the  blood. 
Here  it  comes  into  contact  with  atmospheric  oxygen 
admitted  by  the  lungs.  It  unites  with  the  oxygen  as 
wood  or  coal  might  unite  with  it  in  a  furnace.  The 
matter-products  of  the  union,  if  I  may  use  the  term,  are 
the  same  in  both  cases,  viz.,  carbonic  acid  and  water. 
The  force-products  are  also  the  same — heat  within  the 
body,  or  heat  and  work  outside  the  body.  Thus  far  every 
action  of  the  organism  belongs  to  the  domain  either  of 
physics  or  of  chemistry.  But  you  saw  me  contract  the 
muscle  of  my  arm.  What  enabled  me  to  do  so?  Was  it  or 
was  it  not  the  direct  action  of  my  will?  The  answer  is, 
the  action  of  the  will  is  mediate,  not  direct.  Over  and 
above  the  muscles  the  human  organism  is  provided  with 
long  whitish  filaments  of  medullary  matter,  which  issue 
from  the  spinal  column,  being  connected  by  it  on  the  one 
side  with  the  brain,  and  on  the  other  side  losing  them- 
selves in  the  muscles.  Those  filaments  or  cords  are  the 
nerves,  which  you  know  are  divided  into  two  kinds,  sensor 
and  motor,  or,  if  you  like  the  terms  better,  afferent  and 
efferent  nerves.  The  former  carry  impressions  from  the 
external  world  to  the  brain;  the  latter  convey  the  behests 
of  the  brain  to  the  muscles.  Here,  as  elsewhere,  we  find 
ourselves  aided  by  the  sagacity  of  Mayer,  who  was  the  first 
clearly  to  formulate  the  part  played  by  the  nerves  in  the 
organism.  Mayer  saw  that  neither  nerves  nor  brain,  nor 
both  together,  possessed  the  energy  necessary  to  animal 
motion;  but  he  also  saw  that  the  nerve  could  lift  a  latch 
and  open  a  door,  by  which  floods  of  energy  are  let,  loose. 
"As  an  engineer,"  he  says  with  admirable  lucidity,  "by 
the  motion  of  his  finger  in  opening  a  valve  or  loosening  a 
detent  can  liberate  an  amount  of  mechanical  energy  almost 
infinite  compared  with  its  exciting  cause;  so  the  nerves, 
acting  on  the  muscles,  can  unlock  an  amount  of  power  out 
of  all  proportion  to  the  work  done  by  the  nerves  them- 
selves." The  nerves,  according  to  Mayer,  pull  the  trigger, 
but  the  gunpowder  which  they  ignite  is  stored  in  the 
muscles.  This  is  the  view  now  universally  entertained. 


SCIKNCE  AND  MAN.  609 

The  quickness  of  thought  has  passed  into  a  proverb,  arid 
the  notion  that  any  measurable  time  elapsed  between  the 
infliction  of  a  wound  and  the  feeling  of  the  injury  would 
have  been  rejected  as  preposterous  thirty  years  ago. 
Nervous  impressions,  notwithstanding  the  results  of 
Haller,  were  thought  to  be  transmitted,  if  not  instantane- 
ously, at  all  events  with  the  rapidity  of  electricity.  Hence, 
when  Helmholtz,  in  1851,  affirmed,  as  the  result  of  experi- 
ment, nervous  transmission  to  be  a  comparatively  sluggish 
process,  very  few  believed  him.  His  experiments  may 
now  be  mads  in  the  lecture-room.  Sound  in  air  moves 
at  the  rate  of  1,100  feet  a  second;  sound  in  water  moves 
at  the  rate  of  5,000  feet  a  second;  light  in  ether  moves  at 
the  rate  of  186,000  miles  a  second,  and  electricity  in  free 
wires  moves  probably  at  the  same  rate.  But  the  nerves 
transmit  their  messages  at  the  rate  of  only  70  feet  a  second, 
a  progress  which  in  these  quick  times  might  well  be 
regarded  as  inordinately  slow. 

Your  townsman,  Mr.  Gore,  has  produced  by  electrolysis 
a  kind  of  antimony  which  exhibits  an  action  strikingly 
analogous  to  that  of  nervous  propagation.  A  rod  of  this 
antimony  is  in  such  a  molecular  condition  that  when  you 
scratch  or  heat  one  end  of  the  rod,  the  disturbance  propa- 
gates itself  before  your  eyes  to  the  other  end,  the  onward 
march  of  the  disturbance  being  announced  bv  the  develop- 
ment of  heat  and  fumes  along  the  line  of  propagation.  In 
some  such  way  the  molecules  of  the  nerves  are  successively 
overthrown;  and  if  Mr.  Grore  could  only  devise  some  means 
of  winding  up  his  exhausted  antimony,  as  the  nutritive 
blood  winds  up  exhausted  nerves,  the  comparison  would  be 
complete.  The  subject  may  be  summed  up,  as  Du  Bois- 
Revmond  has  summed  it  up,  by  reference  to  the  case  of  a 
whale  struck  by  a  harpoon  in  the  tail.  If  the  animal 
were  70  feet  long,  a  second  would  elapse  before  the  disturb- 
ance could  reach  the  brain.  But  the  impression  after  its 
arrival  has  to  diffuse  itself  and  throw  the  brain  into  the 
molecular  condition  necessary  to  consciousness.  Then, 
and  not  till  then,  the  command  to  the  tail  to  defend  itself 
is  shot  through  the  motor  nerves.  Another  second  must 
elapse  before  the  command  can  reach  the  tail,  so  that  more 
than  two  seconds  transpire  between  the  infliction  of  the 
wound  and  the  muscular  response  of  the  part  wounded. 
The  interval  required  for  the  kindling  of  consciousness 


610  FRAGMENTS  OF  SCIENCE. 

would  probably  more  than  suffice  for  the  destruction  of  the 
brain  by  lightning,  or  even  by  a  rifle-bullet.  Before  the 
organ  can  arrange  itself  it  may,  therefore,  be  destroyed, 
and  in  such  a  case  we  may  safely  conclude  that  death  is 
painless. 

The  experiences  of  common  life  supply  us  with  copious 
instances  of  the  liberation  of  vast  stores  of  muscular  power 
by  an  infinitesimal  "priming"  of  the  muscles  by  the 
nerves.  We  all  know  the  effect  produced  on  a  "  nervous" 
organization  by  a  slight  sound  which  causes  affright.  An 
aerial  wave,  the  energy  of  which  would  not  reach  a  minute 
fraction  of  that  necessary  to  raise  the  thousandth  of  a  grain 
through  the  thousandth  of  an  inch,  can  throw  the  whole 
human  frame  into  a  powerful  mechanical  spasm,  followed 
by  violent  respiration  and  palpitation.  The  eye,  of  course, 
may  be  appealed  to  as  well  as  the  ear.  Of  this  the  lamented 
Lange  gives  the  following  vivid  illustration: 

A  merchant  sits  complacently  in  his  easy-chair,  not 
knowing  whether  smoking,  sleeping,  newspaper  reading, 
or  the  digestion  of  food  occupies  the  largest  portion  of  his 
personality.  A  servant  enters  the  room  with  the  telegram 
bearing  the  words,  "Antwerp,  etc.  .  .  .  Jonas  and  Co. 
have  failed."  "  Tell  James  to  harness  the  horses!  "  The 
servant  flies.  Up  starts  the  merchant,  wide  awake; 
makes  a  dozen  paces  through  the  room,  descends  to  the 
counting-house,  dictates  letters,  and  forwards  despatches. 
He  jumps  into  his  carriage,  the  horses  snort,  and  their 
driver  is  immediately  at  the  bank,  on  the  Bourse,  and 
among  his  commercial  friends.  Before  an  hour  has  elapsed 
he  is  again  at  home,  where  he  throws  himself  once  more 
into  his  easy-chair  with  a  deep-drawn  sigh,  "  Thank  God 
I  am  protected  against  the  worst,  and  now  for  further 
reflection." 

This  complex  mass  of  action,  emotional,  intellectual, 
and  mechanical,  is  evoked  by  the  impact  upon  the  retina 
of  the  infinitesimal  waves  of  light  coming  from  a  few 
pencil  marks  on  a  bit  of  paper.  We  have,  as  Lange 
says,  terror,  hope,  sensation,  calculation,  possible  ruin, 
and  victory  compressed  into  a  moment.  What  caused 
the  merchant  to  spring  out  of  his  chair?  The  contrac- 
tion of  his  muscles.  What  made  his  muscles  contract? 
An  impulse  of  the  nerves,  which  lifted  the  proper  latch, 


SCIENCE  AND  MAN.  611 

and  liberated  the  muscular  power.  Whence  this  impulse? 
From  the  center  of  the  nervous  system.  But  how  did 
it  originate  there?  This  is  the  critical  question,  to 
which  some  will  reply  that  it  had  its  origin  in  the  human 
soul.  • 

The  aim  and  effort  of  science  is  to  explain  the  unknown 
in  terms  of  the  known.  Explanation,  therefore,  is  condi- 
tioned by  knowledge.  You  have  probably  heard  the  story 
of  the  German  peasant,  who,  in  early  railway  days,  was 
taken  to  see  the  performance  of  a  locomotive.  He  had 
never  known  carriages  to  be  moved  except  by  animal  power. 
Every  explanation  outside  of  this  conception  lay  beyond 
his  experience,  and  could  not  be  invoked.  After  long 
reflection  therefore,  and  seeing  no  possible  escape  from  the 
conclusion,  he  exclaimed  confidently  to  his  companion, 
"  Es  miissen  doch  Pferde  dariu  sein" — There  must  be 
horses  inside.  Amusing  as  this  locomotive  theory  may 
seem,  it  illustrates  a  deep-lying  truth. 

With  reference  to  our  present  question,  some  may  be 
disposed  to  press  upon  me  such  considerations  as  these: 
Your  motor  nerves  are  so  many  speaking-tubes,  through 
which  messages  are  sent  from  the  man  to  the  world;  and 
your  sensor  nerves  are  so  many  conduits  through  which  the 
whispers  of  the  world  are  sent  back  to  the  man.  But  you 
have  not  told  us  where  is  the  man.  Who  or  what  is  it 
that  sends  and  receives  those  messages  through  the  bodily 
organism?  Do  not  the  phenomena  point  to  the  existence 
of  a  self  within  the  self,  which  acts  through  the  body  as 
through  a  skillfully  constructed  instrument?  You  picture 
the  muscles  as  hearkening  to  the  commands  sent  through 
the  motor  nerves,  and  you  picture  the  sensor  nerves  as 
the  vehicles  of  incoming  intelligence;  are  you  not  bound 
to  supplement  this  mechanism  by  the  assumption  of  an 
entity  which  uses  it?  In  other  words,  are  you  not  forced 
by  your  own  exposition  into  the  hypothesis  of  a  free  human 
soul? 

This  is  fair  reasoning  now,  and  at  a  certain  stage  of  the 
world's  knowledge  it  might  well  have  been  deemed  con- 
clusive. Adequate  reflection,  however,  shows  that  instead 
of  introducing  light  into  our  minds,  this  hypothesis  con- 
sidered scientifically  increases  our  darkness.  You  do  not 
in  this  case  explain  the  unknown  in  terms  of  the  known, 
which,  as  stated  above,  is  the  method  of  science,  but  you 


612  FRAGMENTS  OF  SCIENCE. 

explain  the  unknown  in  terms  of  the  more  unknown.  Try 
to  mentally  visualize  this  soul  as  an  entity  distinct  from 
the  body,  and  the  difficulty  immediately  appears.  From 
the  side  of  science  all  that  we  are  warranted  in  stating  is 
that  the  terror,  hope,  sensation,  and  calculation  of  Lange's 
merchant,  are  psychical  phenomena  produced  by,  or  asso- 
ciated with,  the  molecular  processes  set  up  by  waves  of 
light  in  a  previously  prepared  brain. 

When  facts  present  themselves  let  us  dare  to  face  them, 
but  let  the  man  of  science  equally  dare  to  confess  igno- 
rance where  it  prevails.  What  then  is  the  causal  connection, 
if  any,  between  the  objective  and  subjective — between 
molecular  motions  and  states  of  consciousness?  Mv  answer 
is:  I  do  not  see  the  connection,  nor  have  I  as  yet  met  any- 
body who  does.  It  is  no  explanation  to  say  that  the  ob- 
jective and  subjective  effects  are  two  sides  of  one  and  the 
same  phenomenon.  Why  should  tl>e  phenomenon  have 
two  sides?  This  is  the  very  core  of  the  difficulty.  There 
are  plenty  of  molecular  motions  which  do  not  exhibit  this 
two-sided  ness.  Does  water  think  or  feel  when  it  runs  into 
frost  ferns  upon  a  window-pane?  If  not,  why  should  the 
molecular  motion  of  the  brain  be  yoked  to  this  mysterious 
companion — consciousness?  We  can  form  a  coherent 
picture  of  the  physical  processes — -the  stirring  of  the  brain, 
the  thrilling  of  the  nerves,  the  discharging  of  the  muscles, 
and  all  the  subsequent  mechanical  motions  of  the  organ- 
ism. But  we  can  present  to  our  minds  no  picture  of  the 
process  whereby  consciousness  emerges,  either  as  a  neces- 
sary link  or  as  an  accidental  by-product  of  this  series  of 
actions.  Yet  it  certainly  does  emerge — the  prick  of  a  pin 
suffices  to  prove  that  molecular  motion  can  produce  con- 
sciousness. The  reverse  process  of  the  production  of  motion 
by  consciousness  is  equally  unpresentable  to  the  mind. 
We  are  here,  in  fact,  upon  the  boundary  line  of  the 
intellect,  where  the  ordinary  canons  of  science  fail  to 
extricate  us  from  our  difficulties.  If  we  are  true  to  these 
canons,  we  must  deny  to  subjective  phenomena  all  influence 
on  physical  processes.  Observation  proves  that  they 
interact,  but  in  passing  from  one  to  the  other  we  meet 
a  blank  which  mechanical  deduction  is  unable  to  fill. 
Frankly  stated,  we  have  here  to  deal  with  facts  almost 
as  difficult  to  seize  mentally  as  the  idea  of  a  soul.  And 
if  you  are  content  to  make  your  "  soul  "  a  poetic  render- 


SCIENCE  AND  MAN.  613 

ing  of  a  'phenomenon  which  refuses  the  yoke  of  ordinary 
physical  laws,  I,  for  one,  would  not  object  to  this 
exercise  of  ideality.  Amid  all  our  speculative  uncer- 
tainty, however,  there  is  one  practical  point  as  clear  as  the 
day;  namely,  that  the  brightness  and  the  usefulness  of 
life,  as  well  as  its  darkness  and  disaster,  depend  to  a 
great  extent  upon  our  own  use  or  abuse  of  this  miraculous 
organ. 

Accustomed  as  I  am  to  harsh  language,  I  am  quite 
prepared  to  hear  my  "poetic  rendering"  branded  as  a 
Sf  falsehood  "  and  a  "  fib."  The  vituperation  is  unmerited, 
for  poetry,  or  ideality,  and  untruth  are  assuredly  very  dif- 
ferent things.  The  one  may  vivify,  while  the  other  kills. 
When  St.  John  extends  the  notion  of  a  soul  to  "souls 
washed  in  the  blood  of  Christ"  does  he  "  fib? "  Indeed, 
if  the  appeal  to  ideality  is  censurable,  Christ  himself  ought 
not  to  have  escaped  censure.  Nor  did  he  escape  it.  "  How 
can  this  man  give  us  his  flesh  to  eat?"  expressed  the 
skeptical  flouting  of  unpoetic  natures.  Such  are  still 
among  us.  Cardinal  Manning  would  doubtless  tell  any 
Protestant  who  rejects  the  doctrine  of  transubstantiation 
that  he  "  fibs"  away  the  plain  words  of  his  Saviour  when 
he  reduces  "  the  Body  of  the  Lord"  in  the  sacrament  to  a 
mere  figure  of  speech. 

Though  misuse  may  render  it  grotesque  or  insincere,  the 
idealization  of  ancient  conceptions,  when  done  consciously 
and  above  board,  has,  in  my  opinion,  an  important  future. 
We  are  not  radically  different  from  our  historic  ancestors, 
and  any  feeling  which  affected  them  profoundly  requires 
only  appropriate  clothing  to  affect  us.  The  world  will  not 
lightly  relinquish  its  heritage  of  poetic  feeling,  and  meta- 
phvsic  will  be  welcomed  when  it  abandons  its  pretensions 
to  scientific  discovery  and  consents  to  be  ranked  as  a  kind 
of  poetry.  "  A  good  symbol,"  says  Emerson,  "  is  a 
missionary  to  persuade  thousands.  The  Vedas,  the  Edda, 
the  Koran,  are  each  remembered  by  its  happiest  figure. 
There  is  no  more  welcome  gift  to  men  than  a  new  symbol. 
They  assimilate  themselves  to  it,  deal  with  it  in  all  ways, 
and  it  will  last  a  hundred  years.  Then  comes  a  new  genius 
and  brings  another."  Our  ideas  of  God  and  the  soul  are 
obviously  subject  to  this  symbolic  mutation.  They  are  not 
now  what  they  were  a  century  ago.  They  will  not  be  a  cen- 
tury hence  what  they  are  now.  Such  ideas  constitute  a 


614  FRAGMENTS  OF  SCIENCK. 

kind  of  central  energy  in  the  human  mind,  capable,  like 
the  energy  of  the  physical  universe,  of  assuming  various 
shapes  and  undergoing  various  transformations.  They 
baffle  and  elude  the  theological  mechanic  who  would  carve 
them  to  dogmatic  forms.  They  offer  themselves  freely  to 
the  poet  who  understands  his  vocation,  and  whose  function 
is,  or  ought  to  be,  to  find  "local  habitation  •"  for  thoughts 
woven  into  our  subjective  life,  but  which  refuse  to  be 
mechanically  defined. 

We  now  stand  face  to  face  with  the  final  problem.  It 
is  this:  Are  the  brain,  and  the  moral  and  intellectual  proc- 
esses known  to  be  associated  with  the  brain — and,  as  far 
as  our  experience  goes,  indissolubly  associated — subject  to 
the  laws  which  we  find  paramount  in  physical  nature?  Is 
the  will  of  man,  in  others  words,  free,  or  are  it  and  nature 
equally  "  bound  fast  in  fate?"  From  this  latter  conclusion, 
after  he  had  established  it  to  the  entire  satisfaction  of  his 
understanding,  the  great  German  thinker  Fichte  recoiled. 
You  will  find  the  record  of  this  struggle  between  head  and 
heart  in  his  book,  entitled  "  Die  Bestimrnung  des  Men- 
schen" — The  Vocation  of  Man.*  Fichte  was  determined 
at  all  hazards  to  maintain  his  freedom,  but  the  price  he 
paid  for  it  indicates  the  difficulty  of  the  task.  To  escape 
from  the  iron  necessity  seen  everywhere  reigning  in  phys- 
ical nature,  he  turned  defiantly  round  upon  nature  and 
law,  and  affirmed  both  of  them  to  be  the  products  of  his 
own  mind.  He  was  not  going  to  be  the  slave  of  a  thing 
which  he  had  himself  created.  There  is  a  good  deal  to  be 
said  in  favor  of  this  view,  but  few  of  us  probably  would  be 
able  to  bring  into  play  the  solvent  transcendentalism 
whereby  Fichte  melted  his  chains. 

Why  do  some  regard  this  notion  of  necessity  with  terror, 
while  others  do  not  fear  it  at  all?  Has  not  Carlyle  some- 
where said  that  a  belief  in  destiny  is  the  bias  of  all  earnest 
minds?  "  It  is  not  Nature,"  says  Fichte,  "  it  is  Freedom 
itself,  by  which  the  greatest  and  most  terrible  disorders 
incident  to  our  race  are  produced.  Man  is  the  cruelest 
enemy  of  man.'5  But  the  question  of  moral  responsibility 
here  emerges,  and  it  is  the  possible  loosening  of  this 
responsibility  that  so  many  of  us  dread.  The  notion  of 

*  Translated  by  Dr.  William  Smith  of  Edinburgh;  Trtibner,  1873. 


SCIENCE  AND  MAN.  615 

necessity  certainly  failed  to  frighten  Bishop  Butler.  He 
thought  it  untrue — even  absurd — but  he  did  not  fear  its 
practical  consequences.  He  showed,  on  the  contrary,  in 
the  "  Analogy,"  that  as  far  as  human  conduct  is  concerned, 
the  two  theories  of  free-will  and  necessity  would  come  to 
the  same  in  the  end. 

What  is  meant  by  free-will?  Does  it  imply  the  power 
of  producing  events  without  antecedents — of  starting,  as 
it  were,  upon  a  creative  tour  of  occurrences  without  any 
impulse  from  within  or  from  without?  Let  us  consider 
the  point.  If  there  be  absolutely  or  relatively  no  reason 
why  a  tree  should  fall,  it  will  not  fall;  and  if  there  be 
absolutely  or  relatively  no  reason  why  a  man  should  act,  he 
will  not  act.  It  is  true  that  the  united  voice  of  this 
assembly  could  not  persuade  me  that  I  have  not,  at  this 
moment,  the  power  to  lift  my  arm  if  I  wished  to  do  so. 
Within  this  range  the  conscious  freedom  of  my  will  cannot 
be  questioned.  But  what  about  the  origin  of  the  "  wish?  " 
Are  we,  or  are  we  not,  complete  masters  of  the  circum- 
stances which  create  our  wishes,  motives  and  tendencies  to 
action?  Adequate  reflection  will,  I  think,  prove  that  we 
are  not.  What,  for  example,  have  I  had  to  do  with  the 
generation  and  development  of  that  which  some  will  con- 
sider my  total  being,  and  others  a  most  potent  factor  of 
my  total  being — the  living,  speaking  organism  which  now 
addresses  you?  As  stated  at  the  beginning  of  this  dis- 
course, my  physical  and  intellectual  textures  were  woven 
for  me,  not  by  me.  Processes  in  the  conduct  or  regulation 
of  which  I  had  no  share  have  made  me  what  I  am.  Here, 
surely,  if  anywhere,  we  are  as  clay  in  the  hands  of  the 
potter.  It  is  the  greatest  of  delusions  to  suppose  that  we 
come  into  this  world  as  sheets  of  white  paper  on  which  the 
age  can  write  anything  it  likes,  making  us  good  or  bad, 
noble  or  mean,  as  the  age  pleases.  The  age  can  stunt, 
promote,  or  pervert  pre-existent  capacities,  but  it  cannot 
create  them.  The  worthy  Kobert  Owen,  who  saw  in 
external  circumstances  the  great  molders  of  human  char- 
acter, was  obliged  to  supplement  his  doctrine  by  making 
the  man  himself  one  of  the  circumstances.  It  is  as  fatal 
as  it  is  cowardly  to  blink  facts  because  they  are  not  to  our 
taste.  How  many  disorders,  ghostly  and  bodily,  are  trans- 
mitted to  us  by  inheritance?  In  our  courts  of  law,  when- 
ever it  is  a  question  whether  a  crime  has  been  committed 


C 1 6  FRA  GMENTS  OF  SCIENCE. 

under  the  influence  of  insanity,  the  best  guidance  the 
judge  and  jury  can  have  is  derived  from  the  parental 
antecedents  of  the  accused.  If  among  these  insanity  be 
exhibited  in  any  marked  degree,  the  presumption  in  the 
prisoner's  favor  is  enormously  enhanced,  because  the 
experience  of  life  has  taught  both  judge  and  jury  that  • 
insanity  is  frequently  transmitted,  from  parent  to  child. 

I  met,  some  years  ago,  in  a  railway  carriage  the  governor 
of  one  of  our  largest  prisons.  He  was  evidently  an  ob- 
servant and  reflective  man,  possessed  of  wide  experience 
gathered  in  various  parts  of  the  world,  and  a  thorough 
student  of  the  duties  of  his  vocation.  He  told  me  that 
the  prisoners  in  his  charge  might  be  divided  into  three 
distinct  classes.  The  first  class  consisted  of  persons  who 
ought  never  to  have  been  in  prison.  External  accident, 
and  not  internal  taint,  had  brought  them  within  the  grasp 
of  the  law,  and  what  had  happened  to  them  might 
happen  to  most  of  us.  They  were  essentially  men  of  sound 
moral  stamina,  though  wearing  the  prison  garb.  Then 
came  the  largest  class,  formed  of  individuals  possessing  no 
strong  bias,  moral  or  immoral,  plastic  to  the  touch  of 
circumstances,  which  could  mold  them  into  either  good  or 
evil  members  of  society.  Thirdly  came  a  class — happily 
not  a  large  one — whom  no  kindness  could  conciliate  and 
no  discipline  tame.  They  were  sent  into  this  world 
labeled  "incorrigible,"  wickedness  being  stamped,  as  it 
were,  upon  their  organizations.  It  was  an  unpleasant 
truth,  but  as  a  truth  it  ought  to  be  faced.  For  such 
criminals  the  prison  over  which  he  ruled  was  certainly  not 
the  proper  place.  If  confined  at  all,  their  prison  should  be 
on  a  desert  island  where  the  deadly  contagium  of  their 
example  could  not  taint  the  moral  air.  But  the  sea  itself 
he  was  disposed  to  regard  as  a  cheap  and  appropriate  sub- 
stitute for  the  island.  It  seemed  to  him  evident  that  the 
state  would  benefit  if  prisoners  of  the  first  class  were 
liberated;  prisoners  of  the  second  class  educated;  and 
prisoners  of  the  third  class  put  compendiously  under 
water. 

It  is  not,  however,  from  the  observation  of  individuals 
that  the  argument  against  "  free-will,"  as  commonly 
understood,  derives  its  principal  force.  It  is,  as  already 
hinted,  indefinitely  strengthened  when  extended  to  the 
race.  Most  of  you  have  been  forced  to  listen  to  the  out- 


SC1KNCE  AND  MAN.  617 

cries  and  denunciations  which  rang  discordant  through  the 
land  for  some  years  after  the  publication  of  Mr.  Darwin's 
"  Origin  of  Species."  Well,  the  world— even  the  clerical 
world— has  for  the  most  part  settled  down  in  the  belief 
that  Mr.  Darwin's  book  simply  reflects  the  truth  of  nature: 
that  we  who  are  now  "  foremost  in  the  files  of  time"  have 
come  to  the  front  through  almost  endless  stages  of  pro- 
motion from  lower  to  higher  forms  of  life. 

If  to  any  one  of  us  were  given  the  privilege  of  looking 
back  through  the  aeons  across  which  life  has  crept  toward 
its  present  outcome,  his  vision,  according  to  Darwin, 
would  ultimately  reach  a  point  when  the  progenitors  of 
this  assembly  could  not  be  called  human.  From  that 
humble  society,  through  the  interaction  of  its  members 
and  the  storing  up  of  their  best  qualities,  a  better  one 
emerged;  from  this  again  a  better  still;  until  at  length,  by 
the  integration  of  infinitesimals  through  ages  of  amelio- 
ration, we  came  to  be  what  we  are  to-day.  We  of  this 
generation  had  no  conscious  share  in  the  production  of 
this  grand  and  beneficent  result.  Any  and  every  gener- 
ation which  preceded  us  had  just  as  little  share.  The 
favored  organisms  whose  garnered  excellence  constitutes 
our  present  store  owed  their  advantages,  first,  to  what  we 
in  our  ignorance  are  obliged  to  call  "  accidental  variation; " 
and,  secondly,  to  a  law  of  heredity  in  the  passing  of  which 
our  suffrages  were  not  collected.  With  characteristic 
felicity  and  precision  Mr.  Matthew  Arnold  lifts  this  ques- 
tion into  the  free  air  of  poetry,  but  not  out  of  the  atmos- 
phere of  truth,  when  he  ascribes  the  process  of  amel- 
ioration to  "  a  power  not  ourselves  which  makes  for 
righteousness."  If,  then,  our  organisms,  with  all  their 
tendencies  and  capacities,  are  given  to  us  without  our 
being  consulted;  and  if,  while  capable  of  acting  within 
certain  limits  in  accordance  with  our  wishes,  we  are  not 
masters  of  the  circumstances  in  which  motives  and  wishes 
originate;  if,  finally  our  motives  and  wishes  determine  our 
actions — in  what  sense  can  these  actions  be  said  to  be  the 
result  of  free-will? 

Here,  again,  we  are  confronted  with  the  question  of 
moral  responsibility,  which,  as  it  has  been  much  talked  of 
lately,  it  is  desirable  to  meet.  With  the  view  of  removing 
the  fear  of  our  falling  back  into  the  condition  of  "the  ape 
and  tiger,"  so  sedulously  excited  by  certain  writers,  I 


6 1 8  &RA  GMENTS  OF  SCIENCE. 

propose  to  grapple  with  this  question  in  its  rudest  form, 
and  in  the  most  uncompromising  way,  "If,"  says  the 
robber,  the  ravisher,  or  the  murderer,  "  I  act  because  I 
must  act,  what  right  have  you  to  hold  me  responsible  for 
my  deeds?  "  The  reply  is,  "  The  right  of  society  to  protect 
itself  against  aggressive  and  injurious  forces,  whether  they 
be  bound  or  free,  forces  of  nature  or  forces  of  man." 
"  Then,"  retorts  the  criminal,  "you  punish  me  for  what  I 
cannot  help."  "Let  it  be  granted,"  says  society,  "but 
had  you  known  that  the  treadmill  or  the  gallows  was  cer- 
tainly in  store  for  you,  you  might  have  '  helped.'  Let  us 
reason  the  matter  fully  and  frankly  out.  We  may  enter- 
tain no  malice  or  hatred  against  you;  it  is  enough  that 
with  a  view  to  our  own  safety  and  purification  we  are 
determined  that  you  and  such  as  you  shall  not  enjoy  liberty 
of  evil  action  in  our  midst.  You,  who  have  behaved  as  a 
wild  beast,  we  claim  the  right  to  cage  or  kill  as  we  should 
a  wild  beast.  The  public  safety  is  a  matter  of  more  im- 
portance than  the  very  limited  chance  of  your  moral 
renovation,  while  the  knowledge  that  you  have  been  hanged 
by  the  neck  may  furnish  to  others  about  to  do  as  you  have 
done  the  precise  motive  which  will  hold  them  back.  If 
your  act  be  such  as  to  invoke  a  minor  penalty,  then  not 
only  others,  but  yourself,  may  profit  by  the  punishment 
which  we  inflict.  On  the  homely  principle  that  ' a  burnt 
child  dreads  the  fire/  it  will  make  you  think  twice  before 
venturing  on  a  repetition  of  your  crime.  Observe,  finally, 
the  consistency  of  our  conduct.  You  offend,  you  say,  be- 
cause you  cannot  help  offending,  to  the  public  detriment. 
We  punish,  is  our  reply,  because  we  cannot  help  punish- 
ing, for  the  public  good.  Practically,  then,  as  Bishop 
Butler  predicted,  we  act  as  the  world  acted  when  it  sup- 
posed the  evil  deeds  of  its  criminals  to  be  the  products  of 
free- will."* 

"  What,"  I  have  heard  it  argued,  "  is  the  use  of  preach- 
ing about  duty,  if  a  man's  predetermined  position  in  the 
moral  world  renders  him  incapable  of  profiting  by  advice?" 
Who  knows  that  he  is  incapable?  The  preacher's  last 
word  is  a  factor  in  the  man's  conduct,  and  it  may  be  a 

*  An  eminent  church  dignitary  describes  all  this,  not  unkindly,  as 
"truculent  logic."  I  think  it  worthy  of  his  grace's  graver  con- 
sideration. 


SCIENCE  AND  MAN.  619 

most  important  factor,  unlocking  moral  energies  which 
might  otherwise  remain  imprisoned  and  unused.  If  the 
preacher  thoroughly  feels  that  words  of  enlightenment, 
courage,  and  admonition  enter  into  the  list  of  forces  em- 
ployed by  Nature  herself  for  man's  amelioration,  since  she 
gifted  man  with  speech,  he  will  suffer  no  paralysis  to  fall 
upon  his  tongue.  Dung  the  fig-tree  hopefully,  and  not 
until  its  barrenness  has  been  demonstrated  beyond  a  doubt 
let  the  sentence  go  forth,  "Cut  it  down,  why  cumbereth  it 
the  ground?" 

I  remember  when  a  youth  in  the  town  of  Halifax,  some 
two-and-thirty  years  ago,  attending  a  lecture  given  by  a 
young  man  to  a  small  but  select  audience.  The  aspect  of 
the  lecturer  was  earnest  and  practical,  and  his  voice  soon 
riveted  attention.  He  spoke  of  duty,  defining  it  as  a 
debt  owed,  and  there  was  a  kindling  vigor  in  his  words 
which  must  have  strengthened  the  sense  of  duty  in  the 
minds  of  those  who  heard  him.  No  speculations  regard- 
ing the  freedom  of  the  will  could  alter  the  fact  that  the 
words  of  that  young  man  did  me  good.  His  name  was 
George  Dawson.  He  also  spoke,  if  you  will  allow  me 
to  alude  to  it,  of  a  social  subject  much  discussed  at  the 
time — the  Chartist  subject  of  "  leveling."  Suppose,  he 
says,  two  men  to  be  equal  at  night,  and  that  one  rises 
at  six,  while  the  other  sleeps  till  nine  next  morning,  what 
becomes  of  your  leveling?  And  in  so  speaking  he  made 
himself  the  mouthpiece  of  Nature,  which,  as  we  have  seen, 
secures  advance,  not  by  the  reduction  of  all  to  a  common 
level,  but  by  the  encouragement  and  conservation  of  what 
is  best. 

It  may  be  urged  that,  in  dealing  as  above  with  my  hypo- 
thetical criminal,  I  am  assuming  a  state  of  things  brought 
about  by  the  influence  of  religions  which  include  the 
dogmas  of  theology  and  the  belief  in  free-will — a  state, 
namely,  in  which  a  moral  majority  control  and  keep  in  awe 
an  immoral  minority.  The  heart  of  man  is  deceitful  above 
all  things,  and  desperately  wicked.  Withdraw,  then,  our 
theologic  sanctions,  including  the  belief  in  free-will,  and 
the  condition  of  the  race  will  be  typified  by  the  samples 
of  individual  wickedness  which  have  been  above  adduced. 
We  shall  all,  that  is,  become  robbers,  and  ravishers, 
and  murderers.  From  much  that  has  been  written  of  late 
it  would  seem  that  this  astounding  inference  finds  house- 


620  FRAGMENTS  OF  SCIENCE. 

room  in  many  minds.  Possibly,  the  people  who  hold  such 
views  might  be  able  to  illustrate  them  by  individual 
instances. 

The  fear  of  bell's  a  hangman's  whip, 
To  keep  the  wretch  in  order. 

Remove  the  fear,  and  the  wretch,  following  his  natural 
instinct,  may  become  disorderly;  but  I  refuse  to  accept 
him  as  a  sample  of  humanity.  "  Let  us  eat  and  drink, 
for  to-morrow  we  die"  is  by  no  means  the  ethical  conse- 
quence of  a  rejection  of  dogma.  To  many  of  you  the  name 
of  George  Jacob  Holyoake  is  doubtless  familiar,  and  you 
are  probably  aware  that  at  no  man  in  England  has  the 
term  "atheist"  been  more  frequently  pelted.  There  are, 
moreover,  really  few  who  have  more  completely  liberated 
themselves  from  theologic  notions.  Among  working-class 
politicians  Mr.  Holyoake  is  a  leader.  Does  he  exhort  his 
followers  to  "  Eat  and  drink,  for  to-morrow  we  die?"  Not 
so.  In  the  August  number  of  the  Nineteenth  Century 
you  will  find  these  words  from  his  pen:  "  The  gospel  of 
dirt  is  bad  enough,  but  the  gospel  of  mere  material  com- 
fort is  much  worse."  He  contemptuously  calls  the  Comtist 
championship  of  the  workingman,  "the  championship  of 
the  trencher."  He  would  place  "  the  leanest  liberty  which 
brought  with  it  the  dignity  and  power  of  self-help"  higher 
than  "any  prospect  of  a  full  plate  without  it."  Such  is 
the  moral  doctrine  taught  by  this  "atheistic"  leader;  and 
no  Christian, -I  apprehend,  need  be  ashamed  of  it. 

Most  heartily  do  I  recognize  and  admire  the  spiritual 
radiance,  if  I  may  use  the  term,  shed  by  religion  on  the 
minds  and  lives  of  many  personally  known  to  me.  At  the 
same  time  f  cannot  but  observe  how  signally,  as  regards 
the  production  of  anything  beautiful,  religion  fails  in  other 
cases.  '  Its  professor  and  defender  is  sometimes  at  bottom 
a  brawler  and  a  clown.  These  differences  depend  upon 
primary  distinctions  of  character  which  religion  does  not 
remove.  It  may  comfort  some  to  know  that  there  are 
among  us  many  whom  the  gladiators  of  the  pulpit  would 
call  "atheists"  and  "materialists,"  whose  lives,  neverthe- 
less, as  tested  by  any  accessible  standard  of  morality,  would 
contrast  more  than  favorably  with  the  lives  of  those  who 
seek  to  stamp  them  with  this  offensive  brand.  When  I 
say  "offensive,"  I  refer  simply  to  the  intention  of  those 
who  use  such  terms,  and  not  because  atheism  or  material- 


SCIENCE  AND  MAN.  621 

ism,  when  compared  with  many  of  the  notions  ventilated 
in  the  columns  of  religious  newspapers,  has  any  particular 
offensiveness  for  me.  If  I  wished  to  find  men  who  are 
scrupulous  in  their  adherence  to  engagements,  whose 
words  are  their  bond,  and  to  whom  moral  shiftiness  of 
any  kind  is  subjectively  unknown;  if  I  wanted  a  loving 
father,  a  faithful  husband,  an  honorable  neighbor,  and 
a  just  citizen — I  should  seek  him,  and  find  him  among 
the  band  of  "atheists"  to  which  I  refer.  I  have  known 
some  of  the  most  pronounced  among  them  not  only  in 
life  but  in  death — seen  them  approaching  with  open  eyes 
the  inexorable  goal,  with  no  dread  of  a  "  hangman's 
whip,"  with  no  hope  of  a  heavenly  crown,  and  still  as 
mindful  of  their  duties,  and  as  faithful  in  the  discharge  of 
them,  as  if  their  eternal  future  depended  upon  their  latest 
deeds. 

In  letters  addressed  to  myself,  and  in  utterances  addressed 
to  the  public,  Faraday  is  often  referred  to  as  a  sample  of 
the  association  of  religious  faith  with  moral  elevation.  I 
was  locally  intimate  with  him  for  fourteen  or  fifteen  years 
of  my  life,  and  had  thus  occasion  to  observe  how  nearly 
his  character  approached  what  might,  without  extrav- 
agance, be  called  perfection.  He  was  strong  but  gentle, 
impetuous  but  self- restrained;  a  sweet  and  lofty  courtesy 
marked  his  dealings  with  men  and  women;  and  though  he 
sprang  from  the  body  of  the  people,  a  nature  so  fine  might 
well  have  been  distilled  from  the  flower  of  antecedent 
chivalry.  Not  only  in  its  broader  sense  was  the  Christian 
religion  necessary  lo  Faraday's  spiritual  peace,  but  in  what 
many  would  call  the  narrow  sense  held  by  those  described 
by  Faraday  himself  as  "a  very  small  and  despised  sect  of 
Christians,  known,  if  known  at  all,  as  Sandemauians,"  it 
constituted  the  light  and  comfort  of  his  days. 

Were  our  experience  confined  to  such  cases,  it  would 
furnish  an  irresistible  argument  in  favor  of  the  association 
of  dogmatic  religion  with  moral  purity  and  grace.  But, 
as  already  intimated,  our  experience  is  not  thus  confined. 
In  further  illustration  of  this  point,  we  may  compare  with 
Faraday  a  philosopher  of  equal  magnitude,  whose  character, 
including  gentleness  and  strength,  candor  and  simplicity, 
intellectual  power  and  moral  elevation,  singularly  resembles 
that  of  the  great  Sandemanian,  but  who  has  neither  shared 
the  theologic  views  nor  the  religious  emotions  which 


622  FRAGMENTS  0V  SCIENCE. 

formed  so  dominant  a  factor  in  Faraday's  life.  I  allude 
to  Mr.  Charles  Darwin,  the  Abraham  of  scientific  men— a 
searcher  as  obedient  to  the  command  of  truth  as  was  the 
patriarch  to  the  command  of  God.  I  cannot  therefore,  as 
so  many  desire,  look  upon  Faraday's  religious  belief  as  the 
exclusive  source  of  qualities  shared  so  conspicuously  by 
one  uninfluenced  by  that  belief.  To  a  deeper  virtue 
belonging  to  human  nature  in  its  purer  forms  I  am  dis- 
posed to  refer  the  excellence  of  both. 

Superstition  may  be  defined  as  constructive  religion 
which  has  grown  incongruous  with  intelligence.  AVe  may 
admit,  with  Fichte,  "  that  superstition  has  unquestionably 
constrained  its  subjects  to  abandon  many  pernicious  prac- 
tices and  to  adopt  many  useful  ones;"  the  real  loss  accom- 
panying its  decay  at  the  present  day  has  been  thus  clearly 
stated  by  the  same  philosopher:  "  In  so  far  as  these 
lamentations  do  not  proceed  from  the  priests  themselves — 
whose  grief  at  the  loss  of  their  dominion  over  the  human 
mind  we  can  well  understand — but  from  the  politicians, 
the  whole  matter  resolves  itself  into  this,  that  government 
has  thereby  become  more  difficult  and  expensive.  The 
judge  was  spared  the  exercise  of  his  own  sagacity  and  pene- 
tration when,  by  threats  of  relentless  damnation,  lie  could 
compel  the  accused  to  make  confession.  The  evil  spirit 
formerly  performed  without  reward  services  for  which  in 
later  times  judges  and  policemen  have  to  be  paid." 

No  man  ever  felt  the  need  of  a  high  and  ennobling 
religion  more  thoroughly  than  this  powerful  and  fervid 
teacher,  who,  by  the  way,  did  not  escape  the  brand  of 
"atheist."  But  Fichte  asserted  emphatically  the  power 
and  sufficiency  of  morality  in  its  own  sphere.  "  Let  us 
consider,"  he  says,  "  the  highest  which  man  can  possess  in 
the  absence  of  religion — I  mean  pure  morality.  The 
moral  man  obeys  the  law  of  duty  in  his  breast  absolutely, 
because  it  is  a  law  unto  him;  and  he  does  whatever  reveals 
itself  to  him  as  his  duty  simply  because  it  is  duty.  Let 
not  the  impudent  assertion  be  repeated  that  such  an 
obedience,  without  regard  for  consequences,  and  without 
desire  for  consequences,  is  in  itself  impossible  and  opposed 
to  human  nature."  So  much  for  Fichte.  Faraday  was 
equally  distinct.  "I  have  no  intention,"  he  says,  "of 
substituting  anything  for  religion,  but  I  wish  to  take  that 
part  of  human  nature  which  is  independent  of  it.  Moral- 


SCIENCE  AND  MAN.  623 

ity,  philosophy,  commerce,  the  various  institutions  and 
habits  of  society,  are  independent  of  religion  and  may 
exist  without  it."  These  were  the  words  of  his  youth,  but 
they  expressed  his  latest  convictions.  I  would  add,  that 
the  muse  of  Tennyson  never  reached  a  higher  strain  than 
when  it  embodied  the  sentiment  of  duty  in  ^Enone: 

And,  because  right  is  right,  to  follow  right 
Were  wisdom  in  the  scoru  of  consequence. 

Not  in  the  way  assumed  by  our  dogmatic  teachers  has 
the  morality  of  human  nature  been  built  up.  The  power 
which  has  molded  us  thus  far  has  worked  with  stern  tools 
upon  a  very  rigid  stuff.  What  it  has  done  cannot  be  so 
readily  undone;  and  it  has  endowed  us  with  moral  consti- 
tutions which  take  pleasure  in  the  noble,  the  beautiful, 
and  the  true,  just  as  surely  as  it  has  endowed  us  with 
sentient  organisms,  which  find  aloes  bitter  and  sugar  sweet. 
That  power  did  not  work  with  delusions,  nor  will  it  stay 
its  hand  when  such  are  removed.  Facts,  rather  than 
dogmas,  have  been  its  ministers— hunger  and  thirst,  heat 
and  cold,  pleasure  and  pain,  fervor,  sympathy,  aspiration, 
shame,  pride,  love,  hate,  terror,  awe— such  were  the  forces 
whose  interaction  and  adjustment  throughout  an  immeas- 
urable past  wove  the  triplex  web  of  man's  physical, 
intellectual  and  moral  nature,  and  such  are  the  forces  that 
will  be  effectual  to  the  end. 

You  may  retort  that  even  on  my  own  showing  "  the 
power  which  makes  for  righteousness"  has  dealt  in  delu- 
sions; for  it  cannot  be  denied  that  the  beliefs  of  religion,  in- 
cluding the  dogmas  of  theology  and  the  freedom  of  the  will, 
have  had  some  effect  in  molding  the  moral  world.  Granted; 
but  I  do  not  think  that  this  goes  to  the  root  of  the  matter. 
Are  you  quite  sure  that  those  beliefs  and  dogmas  are 
primary,  and  not  derived? — that  they  are  not  the  products, 
instead  of  being  the  creators,  of  man's  moral  nature?  I 
think  it  is  in  one  of  the  Latter- Day  Pamphlets  that  Carlyle 
corrects  a  reasoner,  who  deduced  the  nobility  of  man  from 
a  belief  in  heaven,  by  telling  him  that  he  puts  the  cart 
before  the  horse,  the  real  truth  being  that  the  belief  in 
heaven  is  derived  from  the  nobility  of  man.  The  bird's 
instinct  to  weave  its  nest  is  referred  to  by  Emerson  as 
typical  of  the  force  which  built  cathedrals,  temples,  and 
pyramids: 


624  FRAOMKNTS  OF  SCIENCE. 

Knowest  tbou  what  wove  yon  woodbird's  nest 

Of  leaves  and  feathers  from  her  breast, 

Or  bow  tbe  fish  outbuilt  its  shell, 

Painting  with  morn  each  annual  cell? 

Such  and  so  grew  these  holy  piles 

While  love  and  terror  laid  the  tiles; 

Earth  proudly  wears  the  Parthenon 

As  the  best  gem  upon  her  zone; 

And  Morning  opes  with  haste  her  lids 

To  gaze  upon  the  Pyramids; 

O'er  England's  abbeys  bends  the  sky 

As  on  its  friends  with  kindred  eye; 

For  out  of  Thought's  interior  sphere 

These  wonders  rose  to  upper  air, 

And  Nature  gladly  gave  them  place, 

Adopted  them  into  her  race, 

And  granted  them  an  equal  date 

With  Andes  and  with  Ararat. 

Surely,  many  utterances  which  have  been  accepted  as 
descriptions  ought  to  be  interpreted  as  aspirations,  or  as 
having  their  roots  in  aspiration  instead  of  in  objective 
knowledge.  Does  the  song  of  the  herald  angels,  "  Glory 
to  God  in  the  highest,  and  on  earth  peace,  goodwill  toward 
men,"  express  the  exaltation  and  the  yearning  of  a  human 
soul?  or  does  it  describe  an  optical  and  acoustical  fact — a 
visible  host  and  an  audible  song?  If  the  former,  the 
exaltation  and  the  yearning  are  man's  imperishable 
possession — a  ferment  long  confined  to  individuals,  but 
which  may  by  and  by  become  the  leaven  of  the  race.  If 
the  latter,  then  belief  in  the  entire  transaction  is  wrecked 
by  non-fulfillment.  Look  to  the  East  at  the  present 
moment  as  a  comment  on  the  promise  of  peace  on  earth 
and  goodwill  toward  men.  That  promise  is  a  dream  ruined 
by  the  experience  of  eighteen  centuries,  and  in  that  ruin  is 
involved  the  claim  of  the  "  heavenly  host"  to  prophetic 
vision.  But  though  the  mechanical  theory  proves  un- 
tenable, the  immortal  song  and  the  feelings  it  expresses 
are  still  ours,  to  be  incorporated,  let  us  hope,  in  purer  and 
less  shadowy  forms  in  the  poetry,  philosophy,  and  practice 
of  the  future. 

Thus,  following  the  lead  of  physical  science,  we  are 
brought  without  solution  of  continuity  into  the  presence  of 
problems  which,  as  usually  classified,  lie  entirely  outside 
the  domain  of  physics.  To  these  problems  thoughtful  and 
penetrative  minds  are  now  applying  those  methods  of 
research  which  in  physical  science  have  proved  their  truth 


PROFESSOR  VIROHOW  AND  EVOLUTION.        625 

by  their  fruits.  There  is  on  all  hands  a  growing  repug- 
nance to  invoke  the  supernatural  in  accounting  for  the 
phenomena  of  human  life;  and  the  thoughtful  minds  just 
referred  to,  finding  no  trace  of  evidence  in  favor  of  any 
other  origin,  are  driven  to  seek  in  the  interaction  of  social 
forces  the  genesis  and  development  of  man's  moral  nature. 
If  they  succeed  in  their  search — and  I  think  they  are  sure 
to  succeed — social  duty  will  be  raised  to  a  higher  level  of 
significance  and  the  deepening  sense  of  social  duty  will,  it 
is  to  be  hoped,  lessen,  if  not  obliterate,  the  strifes  and 
heartburnings  which  now  beset  and  disfigure  our  social 
life.  Toward  this  great  end  it  behoves  us  one  and  all  to 
work;  and  devoutly  wishing  its  consummation,  I  have 
the  honor,  ladies  and  gentlemen,  to  bid  you  a  friendly 
farewell. 


CHAPTER  XXXVII. 

PROFESSOR  VIECHOW   AND   EVOLUTION. 

THIS  WORLD  of  ours  has,  on  the  whole,  been  an  inclem- 
ent region  for  the  growth  of  natural  truth;  but  it  may  be 
that  the  plant  is  all  the  hardier  for  the  bendings  and 
buffetings  it  has  undergone.  The  torturing  of  a  shrub, 
within  certain  limits,  strengthens  it.  Through  the  strug- 
gles and  passions  of  the  brute,  man  reaches  his  estate; 
through  savagery  and  barbarism  his  civilization;  and 
through  illusion  and  persecution  his  knowledge  of  nature, 
including  that  of  his  own  frame.  The  bias  toward  natural 
truth  must  have  been  strong  to  have  withstood  and  over- 
come the  opposing  forces.  Feeling  appeared  in  the  world 
before  Knowledge;  anc^ thoughts,  conceptions,  and  creeds, 
founded  on  emotion,  had,  before  the  dawn  of  science, 
taken  root  in  man.  Such  thoughts,  conceptions,  and 
creeds  must  have  met  a  deep  and  general  want;  otherwise 
their  growth  could  not  have  been  so  luxuriant,  nor  their 
abiding  power  so  strong.  This  general  need — this  hunger 
for  the  ideal  and  wonderful — led  eventually  to  the  differen- 
tiation of  a  caste,  whose  vocation  it  was  to  cultivate  the 
mystery  of  life  and  its  surroundings,  and  to  give  shape, 
name,  and  habitation  to  the  emotions  which  that  mystery 
aroused.  '  Even  the  savage  lived,  not  by  bread  alone,  but 
in  a  mental  world  peopled  with  forms  answering  to  his 


626  FRAGMENTS  OF  SCIENCE. 

capacities  and  needs.  As  time  advanced — in  other  words, 
as  the  savage  opened  out  into  civilized  man — these  forms 
were  purified  and  ennobled  until  they  finally  emerged  in 
the  mythology  and  art  of  Greece: 

Where  still  the  magic  robe  of  Poesy 
Wound  itself  lovingly  around  the  Truth.* 

As  poets,  the  priesthood  would  have  been  justified,  their 
deities,  celestial  and  otherwise,  with  all  their  retinue  and 
appliances,  being  more  or  less  legitimate  symbols  and 
personifications  of  the  aspects  of  nature  and  the  phases  of 
the  human  soul.  The  priests,  however,  or  those  among 
them  who  were  mechanics,  and  not  poets,  claimed  objective 
validity  for  their  conceptions,  and  tried  to  base  upon 
external  evidence  that  which  sprang  from  the  innermost 
need  and  nature  of  man.  It  is  against  this  objective  ren- 
dering of  the  emotions — this  thrusting  into  the  region  of 
fact  and  positive  knowledge  of  conceptions  essentially  ideal 
and  poetic — that  science,  consciously  or  unconsciously, 
wages  war.  Religious  feeling  is  as  much  a  verity  as  any 
other  part  of  human,  consciousness;  and  against  it,  on  its 
subjective  side,  the  waves  of  science  beat  in  vain.  But 
when,  manipulated  by  the  constructive  imagination,  mixed 
with  imperfect  or  inaccurate  historic  data,  and  molded  by 
misapplied  logic,  this  feeling  makes  claims  which  traverse 
our  knowledge  of  nature,  science,  as  in  duty  bound,  stands 
as  a  hostile  power  in  its  path.  It  is  against  the  mythologic 
scenery,  if  1  may  use  the  term,  rather  than  against  the  life 
and  substance  of  religion,  that  Science  enters  her  protest. 
Sooner  or  later  among  thinking  people,  that  scenery  will  be 
taken  for  what  it  is  worth — as  an  effort  on  the  part  of  man 
to  bring  the  mystery  of  life  and  nature  within  the  range  of 
his  capacities;  as  a  temporary  aifd  essentially  fluxional 
rendering  in  terms  of  knowledge  of  that  which  transcends 
all  knowledge,  and  admits  only  of  ideal  approach. 

The  signs  of  the  times,  I  think,  point  in  this  direction. 
It  is,  for  example,  the  obvious  aim  of  Mr.  Matthew  Arnold 
to  protect,  amid  the  wreck  of  dogma,  the  poetic  basis  of 
religion.  And  it  is  to  be  remembered  that  under  the  cir- 
cumstances poetry  may  be  the  purest  accessible  truth.  In 

*  "  Da  der  Dichtung  zauberische  Hulle 

Sich  noch  lieblich  um  die  Wahrheit  wand." — Schiller. 


PROFESSOR  VIRCHOW  AND  EVOLUTION.      ®fl 

other  influential  quarters  a  similar  spirit  is  at  work.  In  a 
remarkable  article  published  by  Professor  Knight  of  St. 
Andrews  in  the  September  number  of  the  Nineteenth 
Century,  amid  other  free  utterances,  we  have  this  one: 
"  If  matter  is  not  eternal,  its  first  emergence  into  being  is 
a  miracle  beside  which  all  others  dwindle  into  absolute 
insignificance.  But,  as  has  often  been  pointed  out,  the 
process  is  unthinkable;  the  sudden  apocalypse  of  a  material 
world  out  of  blank  nonentity  cannot  be  imagined;*  its 
emergence  into  order  out  of  chaos  when  'without  form 
and  void  "  of  life,  is  merely  a  poetic  rendering  of  the  doc- 
trine of  its  slow  evolution.'  These  are  all  bold  words  to 
be  spoken  before  the  moral  philosophy  class  of  a  Scotch 
university,  while  those  I  have  underlined  show  a  remark- 
able freedom  of  dealing  with  the  sacred  text.  They  repeat 
in  terser  language  what  1  ventured  to  utter  four  years  ago 
regarding  the  Book  of  Genesis.  "  Profoundly  interesting 
and  indeed  pathetic  to  me  are  those  attempts  of  the  opening 
mind  of  man  to  appease  its  hunger  for  a  Cause.  But  the 
Book  of  Genesis  has  no  voice  in  scientific  questions.  Jtt.i$ 
a  poem,  not  a  scientific  treatise.  In  the  former  aspect  it  is 
forever  beautiful;  in  the  latter  it  has  been,  and  it  will 
continue  to  be,  purely  obstructive  and  hurtful."  My  agree- 
ment with  Professor  Knight  extends  still  further.  "  Does 
the  vital,"  he  asks^"  proceed  by  a  still  remoter  develop- 
ment from  the  non-vital?  '"Or  was  it  created  by  a  fiat  of 
volition ?Q.JOr" — and  here  he  emphasizes  his  question — 
/  "  has  it  always  existed  in  some  form  or  other  as  an  eternal 
constituent  of  the  universe?  I  do  not  see,"  he  replies, 
"  how  we  can  escape  from  the  last  alternative."  With  the 
whole  force  of  my  conviction  I  say,  Nor  do  I,  though  our 
modes  of  regarding  the  ''eternal  constituent"  may  not  be 
the  same. 

When  matter  was  defined  by  Descartes,  he  deliber- 
ately excluded  the  idea  of  force  or  motion  from  its  attri- 
butes and  from  his  definition.  Extension  only  was  taken 
into  account.  And,  inasmuch  as  the  impotence  of  matter 
to  generate  motion  was  assumed,  its  observed  motions 
were  referred  to  an  external  cause.  God,  resident  outside 
of  matter,  gave  the  impulse.  In  this  connection  the 

*  Professor  Knight  will  have  to  reckon  with  the  English  marriage 
service,  one  of  whose  collects  begins  thus:  "O  God,  who  by  thy 
mighty  power  hast  made  all  things  of  nothing." 


028  FRAGMENTS  OF  SCIENCE. 

argument  in  Young's  "Night  Thoughts"  will  occur  to 
most  readers: 

Who  Motion  foreign  to  the  smallest  grain 
Shot  through  vast  masses  of  enormous  weight? 
Who  bid  brute  Matter's  restive  lump  assume 
Such  various  forms,  and  gave  it  wings  to  fly? 

Against  this  notion  of  Descartes  the  great  deist  John 
Toland,  whose  ashes  lie  unmarked  in  Putney  churchyard, 
strenuously  contended.  He  affirmed  motion  to  be  an 
inherent  attribute  of  matter — that  no  portion  of  matter 
was  at  rest,  and  that  even  the  most  quiescent  solids  were 
animated  by  a  motion  of  their  ultimate  particles.  The 
success  of  his  contention,  according  to  the  learned  and 
laborious  Dr.  Berthold,*  entitles  Toland  to  be  regarded  as 
the  founder  of  that  monistic  doctrine  which  is  now  so 
rapidly  spreading. 

It  seems  to  me  that  the  idea  of  vitality  entertained  in 
our  day  by  Professor  Knight,  closely  resembles  the  idea  of 
motion  entertained  by  his  opponents  in  Toland's  day. 
Motion  was  then  virtually  asserted  to  be  a  thing  sui generis, 
distinct  from  matter,  and  incapable  of  being  generated  out 
of  matter.  Hence  the  obvious  inference  when  matter  was 
observed  to  move.  It  was  the  vehicle  of  an  energy  not  its 
own — the  repository  of  forces  impressed  on  it  from  without 
— the  purely  passive  recipient  of  the  shock  of  the 
Divine.  The  logical  form  continues,  but  the  subject- 
matter  is  changed.  "  The  evolution  of  nature/'  says 
Professor  Knight,  "may  be  a  fact;  a  daily  and  hourly 
apocalypse.  But  we  have  no  evidence  of  the  non-vital 
passing  into  the  vital.  Spontaneous  generation  is,  as  yet, 
an  imaginative  guess,  unverified  by  scientific  tests.  And 
matter  is  not  itself  alive.  Vitality,  whether  seen  in  a  single 
cell  of  protoplasm  or  in  the  human  brain,  is  a  thing  sui 
generis,  distinct  from  matter,  and  incapable  of  being 
generated  out  of  matter."  It  may  be,  however,  that  in 
process  of  time,  vitality  will  follow  the  example  of  motion, 
and,  after  the  necessary  antecedent  wrangling,  take  its 
place  among  the  attributes  of  that  "  universal  mother  " 
who  has  been  so  often  misdefined. 

*  "  John  Toland  und  der  Monismus  der  Gegenwart,"  Heidelberg, 
Carl  Winter. 


PROFESSO R  VIRUHO  W  AND  E VOL  UTION.         629 

That  "matter  is  not  itself  alive"  Professor  Knight 
seems  to  regard  as  an  axiomatic  truth.  Let  us  place  in 
contrast  with  this  the  notion  entertained  by  the  philosopher 
Uebervveg,  one  of  the  subtlest  heads  that  Germany  lias 
produced.  "  What  occurs  in  the  brain/'  says  Ueberweg, 
"  would,  in  my  opinion,  not  be  possible,  if  the  process 
which  here  appears  in  its  greatest  concentration  did  not 
obtain  generally,  only  in  a  vastly  diminished  degree.  Take 
a  pair  of  mice  and  a  cask  of  flour.  By  copious  nourish- 
ment the  animals  increase  and  multiply,  and  in  the  same 
proportion  sensations  and  feelings  augment.  The  quantity 
of  these  latter  possessed  by  the  first  pair,  is  not  simply 
diffused  among  their  descendants,  for  in  that  case  the  bust 
must  feel  more  feebly  than  the  first.  The  sensations  and 
feelings  must  necessarily  be  referred  back  to  the  flour, 
where  they  exist,  weak  and  pale  it  is  true,  and  not  concen- 
trated as  they  are  in  the  brain."*  We  may  not  be  able  to 
taste  or  smell  alcohol  in  a  tub  of  fermented  cherries,  but 
by  distillation  we  obtain  from  them  concentrated  Kirsch- 
wasser.  Hence  Ueberweg's  comparison  of  the  brain  to  a 
still,  which  concentrates  the  sensation  and  feeling,  pre- 
existing, but  diluted  in  the  food. 

"  Definitions,"  says  Mr.  Holyoake,f  "grow  as  the  horizon 
of  experience  expands.  They  are  not  inventions,  but 
descriptions  of  the  state  of  a  question.  No  man  sees  all 
through  a  discovery  at  once."  Thus  Descartes'  notion  of 
matter,  and  his  explanation  of  motion,  would  be  put  aside 
as  trivial  by  a  physiologist  •  or  a  crystal lographer  of  the 
present  day.  They  are  not  descriptions  of  the  state  of  the 
question.  And  yet  a  desire  sometimes  shows  itself  in  dis- 
tinguished quarters  to  bind  us  down  to  conceptions  which 
passed  muster  in  the  infancy  of  knowledge,  but  which  are 
wholly  incompatible  with  our  present  enlightenment.  Mr. 
Martineau,  I  think,  errs  when  he  seeks  to  hold  me  to  views 
enunciated  by  "  Democritus  and  the  mathematicians." 
That  definitions  should  change  as  knowledge  advances  is  in 
accordance  both  with  sound  sense  and  scientific  practice. 
When,  for  example,  the  undulatory  theory  was  started,  it 
was  not  imagined  that  the  vibrations  of  light  could  be 

*  Letter  to  Lange:  "  Gesckiclite  des  Materialisrous,"  Bweite  Aufl., 
vol.  ii.,  p.  521. 
f  Nineteenth  Century,  September,  1878. 


630  FRAGMENTS  OF  SCIENCE. 

transverse  to  the  direction  of  propagation.  The  example 
of  sound  was  at  hand,  which  was  a  case  of  longitudinal 
vibration.  Now  the  substitution  of  transverse  for  longi- 
tudinal vibrations  in  the  case  of  light  involved  a  radical 
change  of  conception  as  to  the  mechanical  properties  of  the 
luminiferous  medium.  But  though  this  change  went  so 
far  as  to  fill  space  with  a  substance  possessing  the  proper- 
ties of  a  solid,  rather  than  those  of  a  gas,  the  change  was 
accepted,  because  the  newly  discovered  facts  imperatively 
demanded  it.  Following  Mr.  Marti neau's  example,  the 
opponent  of  the  uudulatory  theory  might  effectually  twit 
the  holder  of  it  on  his  change  of  front.  "  This  ether  of 
yours,"  he  might  say,  "  alters  its  style  with  every  change 
of  service.  Starting  as  a  beggar,  with  scarce  a  rag  of 
'  property'  to  cover  its  bones,  it  turns  up  as  a  prince 
when  large  undertakings  are  wanted.  You  had  some  show 
of  reason  when,  with  the  case  of  sound  before  you,  you 
assumed  your  ether  to  be  a  gas  in  the  last  extremity  of 
attenuation.  But  now  that  new  service  is  rendered 
necessary  by  new  facts,  you  drop  the  beggar's  rags,  and 
accomplish  an  undertaking,  great  and  princely  enough  in 
all  conscience;  for  it  implies  that  not  only  planets  of 
enormous  weight,  but  comets  with  hardly  any  weight  at  all, 
fly  through  your  hypothetical  solid  without  perceptible 
loss  of  motion."  This  would  sound  very  cogent,  but  it 
would  be  very  vain.  Equally  vain,  in  my  opinion,  is  Mr. 
Martineau's  contention  that  we  are  not  justified  in  modify- 
ing, in  accordance  with  advancing  knowledge,  our  notions 
of  matter. 

Before  parting  from  Professor  Knight,  let  me  commend 
his  courage  as  well  as  his  insight.  We  have  heard  much 
of  late  of  "the  peril  to  morality  involved  in  the  decay  of 
religious  belief.  What  Mr.  Knight  says  under  this  head  is 
worthy  of  all  respect  and  attention.  •'  I  admit,"  he-writes, 
"that  were  it  proved  that  the  moral  faculty  was  derived- as 
well  as  developed,  its  present  decisions  would  not  be 
invalidated.  The  child  of  experience  has  a  father  whose 
teachings  are  grave,  peremptory,  and  august;  and  an 
earthborn  rule  may  be  as  stringent  as  any  derived  from  a 
celestial  source.  It  does  not  even  follow  that  a  belief  in 
the  material  origin  of  spiritual  existence,  accompanied  by 
a  corresponding  decay  of  belief  in  immortality,  must 
necessarily  lead  to  a  relaxation  of  the  moral  fiber  of  the 


PROFESSOR  VIRCHOW  AND  EVOLUTION,         631 

race.  It  is  certain  that  it  has  often  done  so.*  But  it  is 
equally  certain  that  there  have  been  individuals,  and  great 
historical  communities,  in  which  the  absence  of  the  latter 
belief  has  neither  weakened  moral  earnestness,  nor  pre- 
vented devotional  fervor."  I  have  elsewhere  stated  that 
some  of  the  best  men  of  my  acquaintance — men  lofty  in 
thought  and  beneficent  in"  act — belong  to  a  class  who 
assiduously  let  the  belief  referred  to  alone.  They  derive 
from  it  neither  stimulus  nor  inspiration,  while — I  say  it 
with  regret — were  I  in  quest  of  persons  who,  in  regard  to 
the  finer  endowments  of  human  character,  are  to  be  ranked 
with  the  unendowed,  I  should  find  some  characteristic 
samples  among  the  noisier  defenders  of  the  orthodox 
belief.  These,  however,  are  but  "  hand-specimens  "  on 
both  sides;  the  wider  data  referred  to  by  Professor  Knight 
constitute,  therefore,  a  welcome  corroboration  of  my  ex- 
perience. Again,  my  excellent  critic,  Professor  Blackie, 
describes  Buddha  as  being  "a  great  deal  more  than  a 
prophet;  a  rare,  exceptional,  and  altogether  transcendental 
.incarnation  of  moral  perfection."!  And  yet,  "what 
\Buddha  preached  was  a  gospel  of  pure  human  ethics,' 
divorced  not  only  from  Brahma  and  the  Brahminic  Trinity, 
but  even  from  the  existence  of  God. "  l\  These  civilized 
and  gallant  voices  from  the  North  contrast  pleasantly  with 
the  barbarous  whoops  which  sometimes  come  to  us  along 
the  same  meridian. 

Looking  backward  from  my  present  standpoint  over  the 
earnest  past,  a  boyhood  fond  of  play  and  physical  action, 
but  averse  to  school  work,  lies  before  me.  The  aversion 
did  not  arise  from  intellectual  apathy  or  want  of  appetite 
for  knowledge,  but  simply  from  the  fact  that  my  earliest 
teachers  lacked  the  power  of  imparting  vitality  to  what 
they  taught.  Athwart  all  play  and  amusement,  however, 
a  thread  of  seriousness  ran  through  rny  character;  arid 
many  a  sleepless  night  of  my  childhood  has  been  passed, 
fretted  by  the  question  "Who  made  God?"  I  was  well 

*  Is  this  really  certain?  Instead  of  standing  in  the  relation  of  cause 
and  effect,  may  not  the  "decay"  and  "relaxation"  be  merely 
coexistent,  both,  perhaps,  flowing  from  common  historic  antecedents? 

f  "  Natural  History  of  Atheism,"  p.  136, 

%  Ibid.,  p.  125. 


632  FRAGMENTS  OF  SCIENCE. 

versed  in  Scripture;  for  I  loved  the  Bible,  and  was 
prompted  by  that  love  to  commit  large  portions  of  it  to 
memory.  Later  on  I  became  adroit  in  turning  my 
Scriptural  knowledge  against  the  Church  of  Rome,  but 
the  characteristic  doctrines  of  that  Church  marked  only 
for  a  time  the  limits  of  inquiry.  The  eternal  Sonship  of 
Christ,  for  example,  as  enunciated  in  the  Athanasian 
Creed,  perplexed  me.  The  resurrection  of  the  body  was 
also  a  thorn  in  my  mind,  and  here  I  remember  that  a  pas- 
sage in  Blair's  "  Grave"  gave  me  momentary  rest. 

Sure  the  same  power 

That  rear'd  the  piece  at  first  and  took  it  down 
Can  reassemble  the  loose,  scatter'd  parts 
And  put  them  as  they  were. 

The  conclusion  seemed  for  the  moment  entirely  fair,  but 
with  further  thought,  my  difficulties  came  back  to  me.  I 
had  seen  cows  and  sheep  browsing  upon  churchyard  grass, 
which  sprang  from  the  decaying  mold  of  dead  men.  The 
flesh  of  these  animals  was  undoubtedly  a  modification  of 
human  flesh,  and  the  persons  who  fed  upon  them  were  as 
undoubtedly,  in  part  a  more  remote  modification  of  the 
same  substance.  I  figured  the  selfsame  molecules  as 
belonging  first  to  one  body  and  afterward  to  a  different 
one,  and  I  asked  myself  how  two  bodies  so  related  could 
possibly  arrange  their  claims  at  the  day  of  resurrection. 
The  scattered  parts  of  each  were  to  be  reassembled  and  set 
as  they  were.  But  if  handed  over  to  the  one,  IIOAV  could 
they  possibly  enter  into  the  composition  of  the  other? 
Omnipotence  itself,  I  concluded,  could  not  reconcile  the 
contradiction.  Thus  the  plank  which  Blair's  mechanical 
theory  of  the  resurrection  brought  momentarily  into  sight 
disappeared,  and  I  was  again  cast  abroad  on  the  waste 
ocean  of  speculation. 

At  the  same  time  I  could  by  no  means  get  rid  of  the  idea 
that  the  aspects  of  nature  and  the  consciousness  of  man 
implied  the  operation  of  a  power  altogether  beyond  my 
grasp — an  energy  the  thought  of  which  raised  the  temper- 
ature of  the  mind,  though  it  refused  to  accept  shape, 
personal  or  otherwise,  from  the  intellect.  Perhaps  the 
able  critics  of  the  Saturday  Review  are  justified  in 
speaking  as  they  sometimes  do  of  Mr.  Carlyle.  They  owe 
him  nothing,  and  have  a  right  to  announce  the  fact  ill 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        633 

their  own  way.  I,  however,  owe  him  a  great  deal,  and  am 
also  in  honor  bound  to  acknowledge  the  debt.  Few,  per- 
haps, who  are  privileged  to  come  into  contact  with  that 
illustrious  man  have  shown  him  a  sturdier  front  than  I 
have,  or  in  discussing  modern  science  have  more  frequently 
withstood  him.  But  I  could  see  that  his  contention  at 
bottom  always  was  that  the  human  soul  has  claims  and 
yearnings  which  physical  science  cannot  satisfy.  England 
to  come  will  assuredly  thank  him  for  his  affirmation  of  the 
ethical  and  ideal  side  of  human  nature.  Be  this  as  it  may, 
at  the  period  now  reached  in  my  story  the  feeling  referred 
to  was  indefinitely  strengthened,  my  whole  life  being  at 
the  same  time  rendered  more  earnest,  resolute,  and  labo- 
rious by  the  writings  of  Carlyle.  Others  also  ministered  to 
this  result.  Emerson  kindled  me,  while  Fichte  power- 
fully stirred  my  moral  pulse.*  In  this  relation  I  cared 
little  for  political  theories  or  philosophic  systems,  but  a 
great  deal  for  tlie  propagated  life  and  strength  of  pure  and 
powerful  minds.  In  tnv  later  schooldays,  under  a  clever 
teacher,  some  knowledge  of  mathematics  and  physics  had 
been  picked  up:  my  stock  of  both  was,  however,  scanty, 
and  I  resolved  to  augment  it.  But  it  was  really  with  the 
view  of  learning  whether  mathematics  and  physics  could 
help  me  in  other  spheres,  rather  than  with  the  desire  of 
acquiring  distinction  in  either  science,  that  I  ventured,  iu 
1848,  to  break  the  continuity  of  my  life,  and  devote  the 
meager  funds  then  at  my  disposal  to  the  study  of  science 
in  Germany. 

But  science  soon  fascinated  me  on  its  own  account.  To 
carry  it  duly  and  honestly  out,  moral  qualities  were  in- 
cessantly invoked.  There  was  no  room  allowed  for  insin- 
cerity— no  room  even  for  carelessness.  The  edifice  of 
science  had  been  raised  by  men  who  had  unswervingly 
followed  the  truth  as  it  is  in  nature;  and  in  doing  so  had 
often  sacrificed  interests  which  are  usually  potent  in  this 
world.  Among  these  rationalistic  men  of  Germany  I 
found  conscientiousness  in  work  as  much  insisted  on  as  it 
could  be  among  theologians.  And  why,  since  they  had 
not  the  rewards  or  penalties  of  the  theologian  to  offer  to 

*  The  reader  will  find  in  the  seventeenth  lecture  of  Fjchte's 
course  on  the  "  Characteristics  of  the  Present  Age  "  a  sample  of  the 
vital  power  of  this  philosopher. 


Q34:  FRAGMENTS  OF  SCIENCE. 

their  disciples?  Because  they  assumed,  and  were  justified 
in  assuming,  that  those  whom  they  addressed  had  that 
within  them  which  would  respond  to  their  appeal.  If 
Germany  should  ever  change  for  something  less  noble  the 
simple  earnestness  and  fidelity  to  duty,  which  in  those  days 
characterized  her  teachers,  and  through  them  her  sons 
generally,  it  will  not  be  because  of  rationalism.  Such  a 
decadent  Germany  might  coexist  with  the  most  rampant 
rationalism  without  their  standing  to  each  other  in  the 
relation  of  cause  and  effect. 

My  first  really  laborious  investigation,  conducted  jointly 
with  my  friend  Professor  Knoblauch,  landed  me  in  a 
region  which  harmonized  vvitli  my  speculative  tastes.  It 
was  essentially  an  inquiry  in  molecular  physics,  having 
reference  to  the  curious,  and  then  perplexing,  phenomena 
exhibited  by  crystals  when  freely  suspended  in  the  mag- 
netic field.  I  here  lived  amid  the  most  complex  operations 
of  magnetism  in  its  twofold  aspect  of  an  attractive  and  a 
repellent  force.  Iron  was  attracted  by  a  magnet,  bismuth 
was  repelled,  and  the  crystals  operated  on  ranged  them- 
selves under  these  two  heads.  Faraday  and  Pliicker  had 
worked  assiduously  at  the  subject,  and  had  invoked  the 
aid  of  new  forces  to  account  for  the  phenomena.  It  was 
soon,  however,  found  that  the  displacement  in  a  crystal  of 
an  atom  of  the  iron  class  by  an  atom  of  the  bismuth  class, 
involving  no  change  of  crystalline  form,  produced  a  com- 
plete reversal  of  the  phenomena.  The  lines  through  the 
crystal  which  were  in  the  one  case  drawn  toward  the  poles 
of  the  magnet,  were  driven,  in  the  other  case,  from  these 
poles.  By  such  instances  and  the  reasoning  which  they 
suggested,  magne-crystallic  action  was  proved  to  be  due, 
not  to  the  operation  of  new  forces,  but  to  the  modification 
of  the  old  ones  by  molecular  arrangement.  Whether 
diamagnetism,  like  magnetism,  was  a  polar  force,  was  in 
those  days  a  subject  of  the  most  lively  contention.  It  was 
finally  proved  to  be  so;  and  the  most  complicated  cases 
of  mague-crystallic  action  were  immediately  shown  to  be 
simple  mechanical  consequences  of  the  principle  of 
diamagnetic  polarity.  These  early  researches,  which 
occupied  in  all  five  years  of  my  life,  and  throughout  which 
the  molecular  architecture  of  crystals  was  an  incessant 
subject  of  mental  contemplation,  gave  a  tinge  and  bias 
to  my  subsequent  scientific  thought,  and  their  influence 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        635 

is  easily  traced  in  my  subsequent  inquiries.  For  example, 
during  nine  years  of  labor  on  the  subject  of  radiation, 
heat  and  light  were  handled  throughout  by  me,  not 
as  ends,  but  as  instruments  by  the  aid  of  which  the  mind 
might  perchance  lay  hold  upon  the  ultimate  particles  of 
matter. 

Scientific  progress  depends  mainly  upon  two  factors 
which  incessantly  interact-/-the  strengthening  of  the  mind 
by  exercise/and  the  illumination  of  phenomena  by  knowl- 
edge. There  seems  no  limit  to  the  insight  regarding 
physical  processes  which  this  interaction  carries  in  its  train. 
Through  such  insight  we  are  enabled  to  enter  and  explore 
that  subsensible  world  into  which  all  natural  phenomena 
strike  their  roots,  and  from  which  they  derive  nutrition. 
By  it  we  are  enabled  to  place  before  the  mind's  eye  atoms 
and  atomic  motions  which  lie  far  beyond  the  range  of  the 
senses,  and  to  apply  to  them  reasoning  as  stringent  as  that 
applied  by  the  mechanician  to  the  motions  and  collisions 
of  sensible  masses.  But  once  committed  to  such  concep- 
tions, there  is  a  risk  of  being  irresistibly  led  beyond  the 
bounds  of  inorganic  nature.  Even  in  those  early  stages  of 
scientific  growth,  I  found  myself  more  and  more  compelled 
to  regard  not  only  crystals,  but  organic  structures,  the 
body  of  man  inclusive,  as  cases  of  molecular  architecture, 
infinitely  more  complex,  it  is  true,  than  those  of  inorganic 
nature,  but  reducible,  in  the  long  run,  to  the  same  mechan- 
ical laws.  In  ancient  journals  1  find  recorded  ponderings 
and  speculations  relating  to  these  subjects,  and  attempts 
made,  by  reference  to  magnetic  and  crystalline  phenomena, 
to  present  some  satisfactory  image  to  the  mind  of  the  way 
in  which  plants  and  animals  are  built  up.  Perhaps  I  may 
be  excused  for  noting  a  sample  of  these  early  speculations, 
already  possibly  known  to  a  few  of  my  readers,  but  which 
here  finds  a  more  suitable  place  than  that  which  it  formerly 
occupied. 

Sitting,  in  the  summer  of  1855,  with  my  friend  Dr. 
Debus  under  the  shadow  of  a  massive  elm  on  the  bank  of 
a  river  in  Normandy,  the  current  of  our  thoughts  and 
conversation  was  substantially  this:  We  regarded  the  tree 
above  us.  In  opposition  to  gravity  its  molecules  had 
ascended,  diverged  into  branches,  and  budded  into  innu- 
merable leaves.  What  caused  them  to  do  so — a  power 


636  FRAGMENTS  OF  SCIENCE. 

external  to  themselves,  or  an  inherent  force?  Science 
rejects  the  outside  builder;  let  us,  therefore,  consider  from 
the  other  point  of  view  the  experience  of  the  present  year.. 
A  low  temperature  had  kept  buck  for  weeks  the  life  of  the 
vegetable  world.  But  at  length  the  sun  gained  power — or, 
rather,  the  cloud-screen  which  our  atmosphere  had  drawn 
between  him  and  us  was  removed — and  life  immediately 
kindled  under  his  warmth.  But  what  is  life,  and  how  can. 
solar  light  and  heat  thus  affect  it?  Near  our  elrn  was  a 
silver  birch,  with  its  leaves  rapidly  quivering  in  the 
morning  air.  We  had  here  motion,  but  not  the  motion  of 
life.  Each  leaf  moved  as  a  mass  under  the  influence  of  an 
outside  force,  while  the  motion  of  life  was  inherent  and 
molecular.  How  are  we  to  figure  this  molecular  motion — 
the  forces  which  it  implies,  and  the  results  which  flow 
from  them?  Suppose  the  leaves  to  be  shaken  from  the- 
tree  and  enabled  to  attract  and  repel  each  other.  To  fix 
the  ideas,  suppose  the  point  of  each  leaf  to  repel  all  the 
other  points  and  to  attract  the  roots,  and  the  root  of  each 
leaf  to  repel  all  other  roots  but  to  attract  the  points.  The 
leaves  would  then  resemble  an  assemblage  of  little 
magnets  abandoned  freely  to  the  interaction  of  their  own 
forces.  In  obedience  to  these  they  would  arrange  them- 
selves, and  finally  assume  positions  of  rest,  forming  a 
coherent  mass.  Let  us  suppose  the  breeze,  which  now 
causes  them  to  quiver,  to  disturb  the  assumed  equilibrium. 
As  often  as  disturbed  there  would  be  a  constant  effort  on 
the  part  of  the  leaves  to  re-establish  it;  and  in  making 
this  effort  the  mass  of  leaves  would  pass  through  different 
shapes  and  forms.  If  other  leaves,  moreover,  were  at 
hand  endowed  with  similar  forces,  the  attraction  would 
extend  to  them — a  growth  of  the  mass  of  leaves  being  the 
consequence.  , 

We  have  strong  reason  for  assuming  that  the  ultimate 
particles  of  matter — the  atoms  and  molecules  of  which  it  is 
made  up — are  endowed  with  forces  coarsely  typified  by 
those  here  ascribed  to  the  leaves.  The  phenomena  of 
crystallization  lead,  of  necessity,  to  this  conception  of 
molecular  polarity.  Under  the  operation  of  such  forces 
the  molecules  of  a  seed,  like  our  fallen  leaves  in  the  first 
instance,  take  up  positions  from  which  they  would  never 
move  if  undisturbed  by  an  external  impulse.  But  solar 
light  and  heat,  which  come  to  us  as  waves  through  space, 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        637 

are  the  great  agents  of  molecular  disturbance.  On  the 
inert  molecules  of  seed  aiid  soil  these  waves  impinge,  dis- 
turbing the  atomic  equilibrium,  which  there  is  an  imme- 
diate effort  to  restore.  The  effort,  incessantly  defeated — 
for  the  waves  continue  to  pour  in — is  incessantly  renewed: 
in  the  molecular  struggle  matter  is  gathered  from  the  soil 
•and  from  the  atmosphere,  and  built,  in  obedience  to  the 
forces  which  guide  the  molecules,  into  the  special  form  of 
the  tree.  In  a  general  way,  therefore,  the  life  of  the  tree 
might  be  defined  as  an  unceasing  effort  to  restore  a  dis- 
turbed equilibrium.  In  the  building  of  crystals  Nature 
makes  her  first  structural  effort;  we  have  here  the  earliest 
groping  of  the  so-called  "  vital  force/'  and  the  manifes- 
tations of  this  force  in  plants  and  animals,  though,  as 
already  stated,  indefinitely  more  complex,  are  to  be  re- 
garded of  the  same  mechanical  quality  as  those  concerned 
in  the  building  of  the  crystal. 

Consider  the  cycle  of  operations  by  which  the  seed  pro- 
duces the  plant,  the  plant  the  flower,  the  flower  again  the 
seed,  the  causal  line,  returning  with  the  fidelity  of  a 
planetary  orbit  to  its  original  point  of  departure.  Who  or 
what  planned  this  molecular  rhythm?  We  do  not  know — 
science  fails  even  to  inform  us  whether  it  was  ever  "  plan- 
ned "  at  all.  Yonder  butterfly  has  a  spot  of  orange  on  its 
wing;  and  if  we  look  at  a  drawing  made  a  century  ago,  of 
one  of  the  ancestors  of  that  butterfly,  we  probably  find  the 
selfsame  spot  upon  the  wing.  For  a  century  the  molecules 
have  described  their  cycles.  Butterflies  have  been  begotten, 
have  been  born,  and  have  died;  still  we  find  the  molecular 
architecture  unchanged.  Who  or  what  determined  this 
persistency  of  recurrence?  We  do  not  know;  but  we  stand 
within  our  intellectual  range  when  we  say  that  there  is 
probably  nothing  in  that  wing  which  may  not  yet  find  its 
Newton  to  prove  that  the  principles  involved  in  its  con- 
struction are  qualitatively  the  same  as  those  brought  into 
play  in  the  formation  of  the  solar  system.  We  may  even 
take  a  step  further,  and  affirm  that  the  brain  of  man — the 
organ  of  his  reason — without  which  he  can  neither  think 
nor  feel,  is  also  an  assemblage  of  molecules,  acting  and 
reacting  according  to  law.  Here,  however,  the  methods 
pursued  in  mechanical  science  come  to  an  end;  and  if 
asked  to  deduce  from  the  physical  interaction  of  the  brain 
molecules  the  least  of  the  phenomena  of  sensation  or 


G38  FRAGMENTS  OF  SCIENCE. 

thought,  I  acknowledge  my  helplessness.  The  association 
of  both  with  the  matter  of  the  brain  may  be  as  certain  as 
the  association  of  light  with  the  rising  of  the  sun.  Bat 
whereas  in  the  latter  case  we  have  unbroken  mechanical 
connection  between  the  sun  and  our  organs,  in  the  former 
case  logical  continuity  disappears.  Between  molecular 
mechanics  and  consciousness  is  interposed  a  fissure  over 
which  the  ladder  of  physical  reasoning  is  incompetent  to 
carry  us.  We  must,  therefore,  accept  the  observed  associ- 
ation as  an  empirical  fact,  without  being  able  to  bring  it 
under  the  yoke  of  a  priori  deduction. 

Such  were  the  ponderings  which  ran  habitually  through 
my  mind  in  the  days  of  my  scientific  youth.  They 
Illustrate  two  things-Ai  determination  to  push  physical 
considerations  to  their  utmost  legitimate  limit;  and  an 
acknowledgment  that  physical  considerations  do  not  lead 
to  the  final  explanation  of  all  that  we  feel  and  know. 
This  acknowledgment,  be  it  said  in  passing,  was  by  no  means 
made  with  the  view  of  providing  room  for  the  play  of  con- 
siderations other  than  physical.  The  same  intellectual 
duality,  if  I  may  use  the  phrase,  manifests  itself  in  the 
following  extract  from  an  article  entitled  "  Physics  and 
Metaphysics,"  published  in  the  Saturday  Review  for 
August  4,  1860: 

"  The  philosophy  of  the  future  will  assuredly  take  more 
account  than  that  of  the  past  of  the  dependence  of  thought 
and  feeling  on  physical  processes;  and  it  may  be  that  the 
qualities  of  the  mind  will  be  studied  through  organic  com- 
binations as  we  now  study  the  character  of  a  force  through 
the  affections  of  ordinary  matter.  We  believe  that  every 
thought  and  every  feeling  has  its  definite  mechanical 
correlative — that  it  is  accompanied  by  a  certain  breaking 
up  and  rernarshaling  of  tne  atoms  of  the  brain.  This 
latter  process  is  purely  physical;  and  were  the  faculties  we 
now  possess  sufficiently  expanded,  without  the  creation  of 
any  new  faculty,  it  would  doubtless  be  within  the  range  of 
our  augmented  powers  to  infer  from  the  molecular  state  of 
the  brain  the  character  of  the  thought  acting  on  it,  and, 
conversely,  to  infer  from  the  thought  the  exact  molecular 
condition  of  the  brain.  We  do  not  say — and  this,  as  will 
be  seen,  is  all-important — that  the  inference  here  referred 
to  would  be  an  a  priori  one.  But  by  observing,  with  the 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        639 

faculties  we  assume,  the  state  of  the  brain  and  the  associ- 
ated mental  affections,  both  might  be  so  tabulated  side  by 
side  that,  if  one  were  given,  a  mere  reference  to  the  table 
would  declare  the  other.  Our  present  powers,  it  is  true, 
shrivel  into  nothingness  when  brought  to  bear  on  such  a 
problem,  but  it  is  because  of  its  complexity  and  our  limits 
that  this  is  the  case.  The  quality  of  the  problem  and  of 
our  powers  are,  we  believe,  so  related,  that  a  mere  expan- 
sion of  the  latter  would  enable  them  to  cope  with  the 
former.  Why,  then,  in  scientific  speculation  should  we 
turn  our  eyes  exclusively  to  the  past?  Mav  it  not  be  that 
a  time  is  coming — ages  no  doubt  distant,  but  still  advanc- 
ing— when  the  dwellers  upon  this  fair  earth,  starting  from 
the  gross  human  brain  of  to-day  as  a  rudiment,  may  be 
able  to  apply  to  these  mighty  questions  faculties  of  com- 
mensurate extent?  Given  the  requisite  expansibility  to 
the  present  senses  and  intelligence  of  man — given  also  the 
time  necessary  for  their  expansion — and  this  high  goal  may 
be  attained.  Development  is  all  that  is  required,  and  not 
a  change  of  quality.  There  need  be  no  absolute  breach  of 
continuity  between  us  and  our  loftier  brothers  yet  to 
come. 

"  We  have  guarded  ourselves  against  saying  that  the 
inferring  of  thought  from  material  combinations  and 
arrangements  would  be  an  inference  a  priori.  The  infer- 
ence meant  would  be  the  same  in  kind  as  that  which  the 
observation  of  the  effects  of  food  and  drink  upon  the  mind 
would  enable  us  to  make,  differing  only  from  the  latter  in 
the  degree  of  analytical  insight  which  we  suppose  attained. 
Given  the  masses  and  distances  of  the  planets,  we  can  infer 
the  perturbations  consequent  on  their  mutual  attractions. 
Given  the  nature  of  a  disturbance  in  water,  air,  or  ether — 
knowing  the  physical  qualities  of  the  medium  we  can  infer 
how  its  particles  will  be  affected.  In  all  this  we  deal  with 
physical  laws.  The  mind  runs  with  certainty  along  the 
line  of  thought  which  connects  the  phenomena,  and  from 
beginning  to  end  there  is  no  break  in  the  chain.  But  when 
we  endeavor  to  pass  by  a  similar  process  from  the  phe- 
nomena of  physics  to  those  of  thought,  we  meet  a  problem 
which  transcends  any  conceivable 'expansion  of  the  powers 
which  we  now  possess.  We  may  think  over  the  subject 
again  and  again,  but  it  eludes  all  intellectual  presentation. 
We  stand  at  length  face  to  face  with  the  Incomprehensible. 


640  FRAGMENTS  OF  SCIENCE. 

The  territory  of  physics  is  wide,  but  it  has  its  limits  from 
which  we  look  with  vacant  gaze  into  the  region  beyond. 
Let  us  follow  matter  to  its  utmost  bounds,  let  us  claim  it 
in  all  its  forms — even  in  the  muscles,  blood,  and  brain  of 
man  himself — as  ours  to  experiment  with  and  to  speculate 
upon.  Casting  the  term  "  vital  force  "from  our  vocab- 
ulary, let  us  reduce,  if  we  can,  the  visible  phenomena  of 
life  to  mechanical  attractions  and  repulsions.  Having 
thus  exhausted  physics,  and  reached  its  very  rim,  a  mighty 
Mystery  still  looms  beyond  us.  We  have,  in  fact,  made 
no  step  toward  its  solution.  And  thus  it  will  ever  loom, 
compelling  the  philosophies  of  successive  ages  to  confess 
that 

"  '  We  are  such  stuff 

As  dreams  are  made  of,  and  our  little  life 

Is  rounded  by  a  sleep.'  " 

In  my  work  on  "  Heat,"  published  in  1863  and  republished 
many  times  since,  I  employ  the  precise  language  thus 
extracted  from  the  Saturday  Review. 

The  distinction  is  here  clearly  brought  out  which  I  had 
resolved  at  all  hazards  to  draw — that,  namely,  between 
what  men  knew  or  might  know,  and  what  they  could  never 
hope  to  know.  Impart  simple  magnifying  power  to  our 
present  vision,  and  the  atomic  motions  of  the  brain  itself 
might  be  brought  into  view.  Compare  these  motions  with 
the  corresponding  states  of  consciousness,  and  an  empirical 
nexus  might  be  established;  but  "we  try  to  soar  in  a 
vacuum  when  we  endeavor  to  pass  by  logical  deduction 
from  the  one  to  the  other."  Among  these  brain-effects  a 
new  product  appears  which  defies  mechanical  treatment. 
We  cannot  deduce  motion  from  consciousness  or  conscious- 
ness from  motion  as  we  deduce  one  motion  from  another. 
Nevertheless  observation  is  open  to  us,  and  by  it  relations 
may  be  established  which  are  at  least  as  valid  as  those  of 
the  deductive  reason.  The  difficulty  may  really  lie  in  the 
attempt  to  convert  a  datum  into  an  inference — an  ultimate 
fact  into  a  product  of  logic.  My  desire  for  the  moment, 
however,  is  not  to  theorize,  but  to  let  facts  speak  in  reply 
to  accusation. 

The  most  "  materialistic  "  speculation  for  which  I  was 
responsible,  prior  to  the  "  Belfast  Address,"  is  embodied 
in  the  following  extract  from  a  brief  article  written  as  far 
back  as  1865:  '-'Supposing  the  molecules  of  the  human 


PROFESSOR  VIROHOW  AND  EVOLUTION.        641 

body,  instead  of  replacing  others,  and  thus  renewing  a 
pre-existing  form,  to  be  gathered  first-hand  from  nature, 
and  placed  in  the  exact  relative  positions  which  they  occupy 
in  the  body.  Supposing  them  to  have  the  same  forces  and 
distribution  of  forces,  the  same  motions  and  distribution 
of  motions — would  this  organized  concourse  of  molecules 
stand  before  us  as  a  sentient,  thinking  being?  There 
seems  no  valid  reason  to  assume  that  it  would  not.  Or 
supposing  a  planet  carved  from  the  sun,  set  spinning  round 
an  axis,  and  sent  revolving  round  the  sun  at  a  distance 
equal  to  that  of  our  earth,  would  one  consequence  of  the 
refrigeration  of  the  mass  be  the  development  of  organic 
forms?  I  lean  to  the  affirmative."  This  is  plain  speaking, 
but  it  is  without  "  dogmatism."  An  opinion  is  ex- 
pressed, a  belief,  a  leaning — not  an  established  "doc- 
trine." 

The  burden  of  my  writings  in  this  connection  is  as 
much  a  recognition  of  the  weakuess  of  science  as  an 
assertion  of  its  strength.  In  1867,  I  told  the  workingmen 
of  Dundee  that  while  making  the  largest  demand  for  free- 
dom of  investigation;  while  considering  science  to  be  alike 
powerful  as  an  instrument  of  intellectual  culture,  and  as  a 
ministrant  to  the  material  wants  of  men;  if  asked  whether 
science  has  solved,  or  is  likely  in  our  day  to  solve,  "  the 
problem  of  the  universe,"  I  must  shake  my  head  in  doubt. 
I  compare  the  mind  of  man  to  a  musical  instrument  with  a 
certain  range  of  notes,  beyond  which  in  both  directions 
exists  infinite  silence.  The  phenomena  of  matter  and 
force  come  within  our  intellectual  range;  but  behind,  and 
above,  and  around  us  the  real  mystery  of  the  universe  lies 
unsolved,  and,  as  far  as  we  are  concerned,  is  incapable  of 
solution. 

"  While  refreshing  my  mind  on  these  old  themes  I  appear 
to  myself  as  a  person  possessing  one  idea,  which  so  over- 
masters him  that  he  is  never  weary  of  repeating  it.  That 
idea  is  the  polar  conception  of  the  grandeur  and  the  little- 
ness of  man — the  vastness  of  his  range  in  some  respects  and 
directions,  and  his  powerlessness  to  take  a  single  step  in 
others,  in  18G8.  before  the  Mathematical  and  Physical 
Section  of  the  British  Association,  then  assembled  at 
Norwich,  I  repeat  the  same  well-worn  note: 

"In  thus  affirming  the  growth  of  the  human  body  to  be 
mechanical,  and  thought  as  exercised  by  us  to  have  its 


642  FRAGMENTS  OF  SCIENCE. 

correlative  in  the  physics  of  the  brain,  the  position  of  the 
'  Materialist/  as  far  as  that  position  is  tenable,  is  stated. 
I  think  the  materialist  will  be  able  finally  to  maintain  this 
position  against  all  attacks,  but  I  do  not  think  he  can  pass 
beyond  it.  The  problem  of  the  connection  of  body  and 
soul  is  as  insoluble  in  its  modern  form  as  it  was  in  the  pre- 
scientific  ages.  Phosphorus  is  a  constituent  of  the  human 
brain,  and  a  trenchant  German  writer  has  exclaimed, 
'  Ohne  Phosphor  kein  gedanke! '  That  may  or  may  not 
be  the  case;  but,  even  if  we  knew  it  to  be  the  case,  the 
knowledge  would  not  lighten  our  darkness.  On  both  sides 
of  the  zone  here  assigned  to  the  materialist  he  is  equally 
helpless.  If  you  ask  him  whence  is  this  'matter'  of 
which  we  have  been  discoursing — who  or  what  divided  it 
into  molecules,  and  impressed  upon  them  this  necessity  of 
running  into  organic  forms — he  has  no  answer.  Science  is 
also  mute  in  regard  to  such  questions.  But  if  the  materi- 
alist is  confounded  and  science  is  rendered  dumb,  who  else 
is  prepared  with  an  answer?  Let  us  lower  our  heads  and 
acknowledge  our  ignorance,  priest  and  philosopher,  one 
and  all." 

The  roll  of  echoes  which  succeeded  the  lecture  delivered 
by  Professor  Virchow  at  Munich  on  September  22,  1877, 
was  long  and  loud.  The  Times  published  a  nearly  full 
translation  of  the  lecture,  and  it  was  eagerly  commented 
on  in  other  journals.  Glances  from  it  to  an  address 
delivered  by  me  before  the  Midland  Institute  in  the 
autumn  of  1877,  and  published  in  this  volume,  were  very 
frequent.  Professor  Virchow  was  held  up  to  me  in  some 
quarters  as  a  model  of  philosophic  cnution,  who  by  his 
reasonableness  reproved  my  rashness,  and  by  his  depth 
reproved  my  shallovvness.  With  true  theologic  courtesy  I 
was  sedulously  emptied,  not  only  of  the  "principles  of 
scientific  thought,"  but  of  "  common  modesty  "  and  "  com- 
mon sense."  And  though  I  am  indebted  to  Professor 
Clifford  for  recalling  in  the  Nineteenth  Century  for 
April  the  public  mind  in  this  connection  from  heated  fancy 
to  sober  fact,  I  do  not  think  a  brief  additional  examination 
of  Virchow's  views,  and  of  my  relation  to  them,  will  be  out 
of  place  here. 

The  keynote  of  his  position  is  struck  in  the  preface  to 
the  excellent  English  translation  of  his  lecture — a  preface 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        643 

written  expressly  by  himself.  "Nothing,"  he  says,  "was 
farther  from  his  intention  than  any  wish  to  disparage  the 
great  services  rendered  by  Mr.  Darwin  to  the  advancement 
of  biological  science,  of  which  no  one  has  expressed  more 
admiration  than  himself.  On  the  other  hand,  it  seemed 
high  time  to  him  to  enter  an  energetic  protest  against  the 
attempts  that  are  made  to  proclaim  the  problems  of  research 
as  actual  facts,  and  the  opinions  of  scientists  as  established 
science."  On  the  ground,  among  others,  that  it  promotes 
the  pernicious  delusions  of  the  Socialist,  Virchow  considers 
the  theory  of  evolution  dangerous;  but  his  fidelity  to  truth 
is  so  great  that  he  would  brave  the  danger  and  teach  the 
theory,  if  it  were  only  proved.  "  However  dangerous  the 
state  of  things  might  be,  let  the  confederates  be  as  mis- 
chievous as  they  might,  still  I  do  not  hesitate  to  say  that 
from  the  moment  when  we  had  become  convinced  that  the 
evolution  theory  was  a  perfectlv  established  doctrine — so 
certain  that  we  could  pledge  our  oath  to  it,  so  sure  that  we 
could  say,  'Thus  it  is' — from  that  moment  we  could  not 
dare  to  feel  any  scruple  about  introducing  it  into  our 
actual  life,  so  as  not  only  to  communicate  it  to  every  edu- 
cated man,  but  to  impart  it  to  every  child,  to  make  it  the 
foundation  of  our  whole  ideas  of  the  world,  of  society, 
and  the  state,  and  to  base  upon  it  our  whole  system  of 
education.  This  I  hold  to  be  a  necessity." 

It  would  be  interesting  to  know  the  persons  designated 
by  the  pronoun  "  we  "  in  the  first  sentence  of  the  foregoing 
quotation.  No  doubt  Professor  Haeckel  would  accept 
this  canon  in  all  its  fullness,  and  found  on  it  his  justifica- 
tion. He  would  say  without  hesitation:  "  I  am  convinced 
that  the  theory  of  evolution  is  a  perfectly  established 
doctrine,  and  hence  on  your  own  showing  I  am  justified 
in  urging  its  introduction  into  our  schools."  It  is  plain, 
however,  that  Professor  Virchow  would  not  accept  this 
retort  as  valid.  His  "  we  "  must  cover  something  more 
than  Professor  Haeckel.  It  would  probably  cover  more 
even  than  the  audience  he  addressed;  for  he  would  hardly 
affirm,  even  if  every  one  of  his  hearers  accepted  the  theory 
of  evolution,  that  that  would  be  a  sufficient  warrant  for 
forcing  it  upon  the  public  at  large.  His  "  we,"  I  submit, 
needs  definition.  If  he  means  that  the  theory  of  evolution 
ought  to  be  introduced  into  our  schools,  not  when  experts 
are  agreed  as  to  its  truth,  but  when  the  community  is  pre- 


644  FRAGMENTS  OF  SCIENCE. 

pared  for  its  introduction,  then,  I  think,  lie  is  right,  and 
that,  as  a  matter  of  social  policy,  Dr.  Haeckel  would  be 
wrong  in  seeking  to  antedate  the  period  of  its  introduction. 
In  dealing  with  the  community  great  changes  must  have 
timeliness  as  well  as  truth  upon  their  side.  But  if  the 
mouths  of  thinkers  be  stopped,  the  necessary  social  prepa- 
ration will  be  impossible;  an  unwholesome  divorce  will  be 
established  between  the  expert  and  the  public,  and  the 
slow  and  natural  process  of  leavening  the  social  lump  by 
discovery  and  discussion  will  be  displaced  by  something 
far  less  safe  and  salutary. 

The  burden,  however,  of  this  celebrated  lecture  is  a 
warning  that  a  marked  distinction  ought  to  be  made  be- 
tween that  which  is  experimentally  proved,  and  that  which 
is  still  in  the  region  of  speculation.  As  to  the  latter, 
Virchow  by  no  means  imposes  silence.  He  is  far  too 
sagacious  a  man  to  commit  himself,  at  the  present  time  of 
day,  to  any  such  absurdity.  But  he  insists  that  it  ought 
not  to  be  put  on  the  same  evidential  level  as  the  former. 
"It  ought,"  as  he  poetically  expresses  it,  "to  be  written 
in  small  letters  under  the  text/'  The  audience  ought  to  be 
warned  that  speculative  matter  is  only  possible,  not  actual 
truth — that  it  belongs  to  the  region  of  "belief,"  and  not 
to  that  of  demonstration.  As  long  as  a  problem  continues 
in  this  speculative  stage  it  would  be  mischievous,  he  con- 
siders, to  teach  it  in  our  schools.  "We  ought  not,"  he 
urges,  "  to  represent  our  conjecture  as  a  certainty,  nor  our 
hypothesis  as  a  doctrine:  this  is  inadmissible."  With 
regard  to  the  connection  between  physical  processes  and 
mental  phenomena  he  says:  "I  will,  indeed,  willingly 
grant  that  we  can  find  certain  gradations,  certain  definite 
points  at  which  we  trace  a  passage  from  mental  processes 
purely  physical,  or  of  a  physical  character.  Throughout 
this  discourse  I  am  not  asserting  that  it  will  never  be 
possible  to  bring  psychical  processes  into  an  immediate 
connection  with  those  that  are  physical.  All  I  say  is  that 
we  have  at  present  no  right  to  set  up  this  possible  connec- 
tion as  a  doctrine  of  science."  In  the  next  paragraph  he 
reiterates  his  position  with  reference  to  the  introduction  of 
such  topics  into  school  teaching.  "  We  must  draw,"  he 
says,  "a strict  distinction  between  what  we  wish  to  teach, 
and  what  we  wish  to  search  for.  The  objects  of  our  re- 
search are  expressed  as  problems  (or  hypotheses).  We 


PROFESSOR  VIRVHOW  AND  EVOLUTION.        645 

need  not  keep  them  to  ourselves;  we  are  ready  to  communi- 
cate them  to  all  the  world,  and  say  '  There  is  the  problem; 
that  is  what  we  strive  for.'  .  .  .  The  investigation  of  such 
problems,  in  which  the  whole  nation  may  be  interested, 
cannot  be  restricted  to  any  one.  This  "is  Freedom  of 
Inquiry.  But  the  problem  (or  hypothesis)  is  not,  without 
further  debate,  to  be  made  a  doctrine."  He  will  not  con- 
cede to  Dr.  Haeckel  "that  it  is  a  question  for  the  school* 
masters  to  decide,  whether  the  Darwinian  theory  of  man's 
descent  should  be  at  once  laid  down  as  the  basis  of  instruc- 
tion, and  the  protoplastic  soul  be  assumed  as  the  foundation 
of  all  ideas  concerning  spiritual  being."  The  professor 
concludes  his  lecture  thus:  "  With  perfect  truth  did  Bacon 
say  of  old  '  Scientia  est  potential  But  he  also  defined 
that  knowledge;  and  the  knowledge  he  meant  was  not 
speculative  knowledge,  not  the  knowledge  of  hypotheses, 
but  it  was  objective  and  actual  knowledge.  Gentlemen,  I 
think  we  should  be  abusing  our  power,  we  should  be  im- 
periling our  power,  unless  in  our  teaching  we  restrict 
ourselves  to  this  perfectly  safe  and  unassailable  domain. 
From  this  domain  we  may  make,  incursions  into  the  field  of 
problems,  and  I  am  sure  that  every  venture  of  that  kind 
will  then  find  all  needful  security  and  support."  I  have 
emphasized  by  italics  two  sentences  in  the  foregoing  series 
of  quotations;  the  other  italics  are  the  author's  own. 

Virchow's  position  could  not  be  made  clearer  by  any 
comments  of  mine  than  he  has  made  it  himself.  That 
position  is  one  of  the  highest  practical  importance. 
"  Throughout  our  whole  German  Fatherland,"  he  says, 
"men  are  busied  in  renovating,  extending,  and  developing 
the  system  of  education,  and  in  inventing  fixed  forms  in 
which  to  mold  it.  On  the  threshold  of  coming  events 
stands  the  Prussian  law  of  education.  In  all  the  German 
states  larger  schools  are  being  built,  new  educational 
establishments  are  set  up,  the  universities  are  extended, 
'higher'  and  '  middle'  schools  are  founded.  Finally 
comes  the  question,  What  is  to  be  the  chief  substance  of 
the  teaching?  "  What  Virchow  thinks  it  ought  and  ought 
not  to  be,  is  disclosed  by  the  foregoing  quotations.  There 
ought  to  be  a  clear  distinction  made  between  science  in 
the  state  of  hypothesis,  and  science  in  the  state  of  fact.  In 
school  teaching  the  former  ought  to  be  excluded.  And, 
as  he  assumes  it  to  be  still  in  its  hypothetical  stage,  the 


646  FRAGMENTS  OF  SCIENCE. 

ban  of  exclusion  ought,  he  thinks,  to  fall  upon  the  theory 
of  evolution. 

I  now  freely  offer  myself  for  judgment  before  the 
tribunal  whose  law  is  here  laid  down.  First  and  foremost, 
then,  I  have  never  advocated  the  introduction  of  the 
theory  of  evolution  into  our  schools.  I  should  even  be 
disposed  to  resist  its  introduction  before  its  meaning  had 
been  better  understood  and  its  utility  more  fully  recog- 
nized than  it  is  now  by  the  great  body  of  the  community. 
The  theory  ought,  I  think,  to  bide  its  time  until  the 
free  conflict  of  discovery,  argument,  and  opinion  has 
won  for  it  this  recognition.  A  necessary  condition 
here,  however,  is  that  free  discussion  should  not  be 
prevented,  either  by  the  ferocity  of  reviewers  or  the  arm 
of  the  law;  otherwise,  as  I  said  before,  the  work  of 
social  preparation  cannot  go  on.  On  this  count,  then, 
I  claim  acquittal,  being  for  the  moment  on  the  side  of 
Virchow. 

Besides  the  duties  of  the  chair,  which  I  have  been  privi- 
leged to  occupy  in  London  for  more  than  a  quarter  of  a 
century,  and  which  never  involved  a  word  on  my  part,  pro 
or  con,  in  reference  to  the  theorv  of  evolution,  I  have  had 
the  honor  of  addressing  audiences  in  Liverpool,  Belfast, 
and  Birmingham;  and  in  these  addresses  the  theory  of 
evolution,  and  the  connected  doctrine  of  spontaneous  gen- 
eration, have  been  more  or  less  touched  upon.  Let  us 
now  examine  whether  in  my  references  I  have  departed 
from  the  views  of  Virchow  or  not. 

in  the.  Liverpool  discourse,  after  speaking  of  the  theory 
of  evolution  when  applied  to  the  primitive  condition  of 
matter,  as  belonging  to  "  the  dim  twilight  of  conjecture/' 
and  affirming  that  "  the  certainty  of  experimental  inquiry 
is  here  shut  out,"  I  sketch  the  nebular  theory  as  enun- 
ciated by  Kant  and  Laplace,  and  afterward  proceed  thus: 
"  Accepting  some  such  view  of  the  construction  of  our 
system  as  probable,  a  desire  immediately  arises  to  connect 
the  present  life  of  our  planet  with  the  past.  We  wish  to 
know  something  of  our  remotest  ancestry.  On  its  first 
detachment  from  the  sun,  life,  as  we  understand  it,  could 
not  have  been  present  on  the  earth.  How,  then,  did  it 
come  there?  The  thing  to  be  encouraged  here  is  a  reverent 
freedom — a  freedom  preceded  by  the  hard  discipline  which 


PROFESSOR  V IRC  HOW  AND  EVOLUTION.        647 

checks  licentiousness  in  speculation — while  the  thing  to 
be  repressed,  both  in  science  and  out  of  it,  is  dogmatism. 
And  here  I  arn  in  the  hands  of  the  meeting,  willing  to  end 
but  ready  to  go  on.  I  have  no  right  to  intrude  upon  you 
unasked  the  unformed  notions  which  are  floating  like  clouds, 
or  gathering  to  more  solid  consistency  in  the  modern  specu- 
lative mind." 

I  then  notice  more  especially  the  basis  of  the  theory. 
"Those  who  hold  the  doctrine  of  evolution  are  by  no 
means  ignorant  of  the  uncertainty  of  their  data,  and  they 
only  yield  to  it  a  provisional  assent.  They  regard  the 
nebular  hypothesis  as  probable;  and,  in  the  utter  absence 
of  any  proof  of  the  illegality  of  the  act,  they  prolong  the 
method  of  nature  from  the  present  into  the  past.  Here 
the  observed  uniformity  of  nature  is  their  only  guide. 
Having  determined  the  elements  of  their  curve  in  a  world 
of  observation  and  experiment,  they  prolong  that  curve  into 
an  antecedent  world,  and  accept  as  probable  the  unbroken 
sequence  of  development  from  the  nebula  to  the  present 
time."  Thus  it  appears  that,  long  antecedent  to  the  pub- 
lication of  his  advice,  I  did  exactly  what  Professor  Virchow 
recommends,  showing  myself  as  careful  as  he  could  be  not 
to  claim  for  a  scientific  doctrine  a  certainty  which  did  not 
belong  to  it. 

I  now  pass  on  to  the  Belfast  Address,  and  will  cite  at 
once  from  it  the  passage  which  has  given  rise  to  the  most 
violent  animadversion.  "  Believing  as  I  do  in  the  contin- 
uity of  nature,  I  cannot  stop  abruptly  where  our  micro- 
scopes cease  to  be  of  use.  At  this  point  the  vision  of  the 
mind  authoritatively  supplements  that  of  the  eye.  By  an 
intellectual  necessity  I  cross  the  boundary  of  the  experi- 
mental evidence,  and  discern  in  that  '  matter'  which  we, 
iu  our  ignorance  of  its  latent  powers,  and  notwithstanding 
our  professed  reverence  for  its  Creator,  have  hitherto 
covered  with  opprobrium,  the  promise  and  potency  of  all 
terrestrial  life."  Without  halting  for  a  moment  I  go  on 
to  do  the  precise  thing  which  Professor  Virchow  declares 
to  be  necessary.  "  If  you  ask  me,"  I  say,  "  whether  there 
exists  the  least  evidence  to  prove  that  any  form  of  life  can 
be  developed  out  of  matter  independently  of  antecedent 
life,  my  reply  is  that  evidence  considered  perfectly  con- 
clusive by  many  has  been  adduced,  and  that  were  we  to 
follow  a  'common  example,  and  accept  testimony  because 


648  FHAGMKNTS 

it  falls  in  with  our  belief,  \ve  should  eagerly  close  with  the 
evidence  referred  to.  But  there  is  in  the  true  man  of 
science  a  desire  stronger  than  the  wish  to  have  his  beliefs 
upheld;  namely,  the  desire  to  have  them  true.  And  those 
to  whom  I  refer  as  having  studied  this  question,  believing 
the  evidence  offered  in  favor  of  '  spontaneous  generation  ' 
to  be  vitiated  by  error,  cannot  accept  it.  They  know  full 
well  that  the  chemist  now  prepares  from  inorganic  matter 
a  vast  array  of  substances,  which  were  some  time  ago 
regarded  as  the  products  solely  of  vitality.  They  are 
intimately  acquainted  with  the  structural  power  of 
matter,  as  evidenced  in  the  phenomena  of  crystallization. 
They  can  justify  scientifically  their  belief  in  its  potency, 
under  the  proper  conditions,  to  produce  organisms.  But, 
in  reply  to  your  question,  they  will  frankly  admit  their 
inability  to  point  to  any  satisfactory  experimental  proof 
that  life  can  be  developed,  save  from  demonstrable  antece- 
dent life."  * 

Comparing  the  theory  oLevolution  with  other  theories, 
I  thus  express  myself  :  \  The  basis  of  the  doctrine  of 
evolution  consists,  not  in  an  experimental  demonstration — 
for  the  subject  is  hardly  accessible  to  this  mode  of  proof — 
but  in  its  general  harmony  with  scientific  thought.  •  From 
contrast,  moreover,  it  derives  enormous  relative  strength. 
On  the  one  side  we  have  a  theory,  which  converts  the 
Power  whose  garment  is  seen  in  the  visible  universe  into 
an  Artificer,  fashioned  after  the  human  model,  and  acting 
by  broken  efforts,  as  man  is  seen  to  act.  On  the  other  side 
we  have  the  conception  that  all  we  see  around  us  and  feel 
within  us — the  phenomena  of  physical  nature  as  well  as 
those  of  the  human  mind — have  their  unsearchable  roots 
in  a  cosmical  life,  if  I  dare  apply  the  term,  an  infinitesimal 
span  of  which  is  offered  to  the  investigation  of  man." 
Among  thinking  people,  in  my  opinion,  this  last  concep- 
tion has  a  higher  ethical  value  than  that  of  a  personal 
artificer.  Be  that  as  it  may,  I  make  here  no  claim  for  the 
theory  of  evolution  which  can  reasonably  be  refused. 

"  Ten  years  have  elapsed,"  said  Dr.  Hooker  at  Norwich 
in  1868,  f  "since  the  publication  of  'The  Origin  of 
Species  by  Natural  Selection/  and  it  is  therefore  not  too 

*  Quoted  by  Clifford,  Nineteenth  Century,  3,  p.  726. 
f  President's  Address  to  the  British  Association. 


PROFESSOR  vuiciiow  AND  ^VOLUTION.     049 

early  now  to  ask  what  progress  that  bold  theory  has  made 
in  scientific  estimation.  Since  the  *  Origin'  appeared  it 
has  passed  through  four  English  editions,*  two  American, 
two  German,  two  French,  several  Eussian,  a  Dutch,  and 
an  Italian  edition.  So  far  from  Natural  Selection  being  a 
thing  of  the  past  [the  '  Athenaeum'  had  stated  it  to  be 
so]  it  is  an  accepted  doctrine  with  almost  every  philo- 
sophical naturalist,  including,  it  will  always  be  understood, 
a  considerable  proportion  who  are  not  prepared  to  admit 
that  it  accounts  for  all  Mr.  Darwin  assigns  to  it."  In  the 
following  year,  at  Innsbruck,  Helmholtz  took  up  the  same 
ground,  f  Another  decade  has  now  passed,  and  he  is 
simply  blind  who  cannot  see  the  enormous  progress  made 
by  the  theory  during  that  time.  SonTe  of  the~6utward  and 
visible  signs  of  this  advance  are  readily  indicated. A  The 
hostility  and  fear  which  so  long  prevented  the  recognition 
of  Mr.  Darwin  by  his  own  university  have  vanished,  and 
this  year  Cambridge,  amid  universal  acclamation,  con- 
ferred on  him  her  Doctor's  degree.  '  The  Academy  of 
Sciences  in  Paris,  which  had  so  long  persistently  closed  its 
doors  against  Mr.  Darwin,  has  also  yielded  at  last;  while 
sermons,  lectures,  and  published  articles  plainly  show  that 
even  the  clergy  have,  to  a  great  extent,  become  acclimatized 
to  the  Darwinian  air.  My  brief  reference  to  Mr.  Darwin 
in  the  Birmingham  Address  was  based  upon  the  knowledge 
that  such  changes  had  been  accomplished,  and  were  still 
going  on. 

That  the  lecture  of  Professor  Virchow  can,  to  any 
practical  extent,  disturb  this  progress  of  public  faith  in  the 
theory  of  evolution,  I  do  not  believe.  That  the  special 
lessons  of  caution  which  he  inculcates  were  exemplified  by 
me,  years  before  his  voice  was  heard  upon  this  subject,  has 

*  Published  by  Mr.  John  Murray,  the  English  publisher  of  Vir- 
chow's  lecture.  Bane  and  antidote  are  thus  impartially  distributed 
by  the  same  hand. 

f  "  Noch  besteht  lebhafter  Streit  urn  die  Wahrheit  oder  Wahr- 
scheinlichkeit  von  Darwin's  Theorie;  er  dreht  sich  aber  doch  eigent- 
lich  nur  um  die  Grenzen,  welche  wir  fur  die  Veranderlichkeit  der 
Arten  annehmen  dlirfen.  Dass  innerhalb  derselben  Species  erbliche 
Racenverschiedenheiten  auf  die  von  Darwin  beschriebeue  Weise  zu 
kommen  konnen,  ja  dass  viele  der  bisher  als  verschiedene  Species 
derselben  Gattung  betrachteten  Formen  von  derselben  Urform 
abstammen,  werden  auch  seine  (iegner  kaum  leugnen." — (Popular^ 
Vortrage.) 


650  FRAGMENTS  OF  SCIENCE. 

been  proved  in  the  foregoing  pages.  In  point  of  fact,  if 
he  had  preceded  me  instead  of  following  me,  and  if  my 
desire  had  been  to  incorporate  his  wishes  in  my  words,  I 
could  not  have  accomplished  this  more  completely.  It  is 
possible,  moreover,  to  draw  the  coincident  lines  still  fur- 
ther, for  most  of  what  he  has  said  about  spontaneous 
generation  might  have  been  uttered  by  me.  /  I  share  his 
opinion  that  the  theory  of  evolution  in  its  complete  form 
involves  the  passage  from  matter  which  we  now  hold  to  be 
inorganic  into  orgauized  matter;  in  other  words,  involves 
the  assumption  that  at  some  period  or  other  of  the  earth's 
history  there  occurred  what  would  be  now  called 
"spontaneous  generation."  I  agree  with  him  that  "  the 
proofs  of  it  are  still  wanting."  "AVhoever,"  he  says, 
"  recalls  to  rnind  the  lamentable  failure  of  all  the  attempts 
made  very  recently  to  discover  a  decided  support  for  the 
generatio  cequivoca  in  the  lower  forms  of  transition  from 
the  inorganic  to  the  organic  world  will  feel  it  doubly 
serious  to  demand  that  this  theory,  so  utterly  discredited, 
should  be  in  any  way  accepted  as  the  basis  of  all  our  views 
of  life."  I  hold  with  Virchow  that  the  failures  have  been 
lamentable,  that  the  doctrine  is  utterly  discredited.  But 
my  position  here  is  so  well  known  that  1  need  not  dwell 
upon  it  further. 

With  one  special  utterance  of  Professor  Virchow  his 
translator  connects  me  by  name.  "  I  have  no  objection," 
observes  the  professor,  "  to  your  saying  that  atoms  of 
carbon  also  possess  mind,  or  that  in  their  connection  with 
the  Plastidule  company  they  acquire  mind;  only  /  do  not 
know  liow  I  am  to  perceive  this."  This  is  substantially 
what  I  had  said  seventeen  years  previously  in  the  Saturday 
Revieiu.  The  professor  continues:  "  If  I  explain  attraction 
and  repulsion  as  exhibitions  of  mind,  as  psychical  phe- 
nomena, I  simply  throw  the  Psyche  out  of  the  window,  and 
the  Psyche  ceases  to  be  a  Psyche."  I  may  say,  in  passing, 
that  the  Psyche  that  could  be  cast  out  of  the  window  is  not 
worth  house-room.  '  At  this  point  the  translator,  who  is 
evidently  a  man  of  culture,  strikes  in  with  a  foot-note. 
"  As  an  illustration  of  Professor  Virchow's  meaning,  we 
may  quote  the  conclusion  at  which  Doctor  Tyndall  arrives 
respecting  the  hypothesis  of  a  human  soul,  offered  as  an 
explanation  or  a  simplification  of  a  series  of  obscure  phe- 
nomena— psychical  phenomena,  as  he  calls  them.  'If  you 


PROFESSOR  VIRCHO  W  AND  E VOL  UTION.        651 

are  content  to  make  your  soul  a  poetic  rendering  of  a 
phenomenon  which  refuses  the  yoke  of  ordinary  physical 
laws,  I,  for  one,  would  not  object  to  this  exercise  of 
ideality/"**  Professor  Virchow's  meaning,  I  admit,  re- 
quired illustration;  but  I  do  not  clearly  see  how  the 
quotation  from  me  subserves  this  purpose.  I  do  not  even 
know  whether  I  am  cited  as  meriting  praise  or  deserving 
opprobrium.  In  a  far  coarser  fashion  this  utterance  of 
mine  has  been  dealt  with  in  other  places:  it  may  therefore 
be  worth  while  to  spend  a  few  words  upon  it. 

The  sting  of  a  wasp  at  the  finger-end  announces  itself  to 
the  brain  as  pain.  The  impression  made  by  the  sting 
travels,  in  the  first  place,  with  comparative  slowness  along 
the  nerves  affected;  and  only  when  it  reaches  the  brain 
have  we  the  fact  of  consciousness.  Those  who  think  most 
pofoundly  on  this  subject  hold  that  a  chemical  change, 
which,  strictly  interpreted,  is  atomic  motion,  is  in  such  a 
case,  propagated  along  the  nerve,  and  communicated  to 
the  brain.  Again,  on  feeling  the  sting*  I  flap  the  insect 
violently  away.  What  has  caused  this  motion  of  my  hand? 
The  command  from  the  brain  to  remove  the  insect  travels 
along  the  motor  nerves  to.,  the  proper  muscles,  and,  their 
force  being  unlocked,  they  perform  the  work  demanded  of 
them.  But  what  moved  the  nerve  molecules  which  un- 
locked the  muscle?  The  sense  of  pain,  it  may  be  replied. 
But  how  can  a  sense  of  pain,  or  any  other  state  of  conscious- 
ness, make  matter  move?  Not  all  the  sense  of  pain  or 
pleasure  in  the  world  could  lift  a  stone  or  move  a  billiard- 
ball;  why  should  it  stir  a  molecule?  Try  to  express  the 
motion  numerically  in  terms  of  the  sensation,  and  the 
difficulty  immediately  appears.  Hence  the  idea  long  ago 
entertained  by  philosophers,  but  lately  brought  into  special 
prominence,  that  the  physical  processes  are  complete  in 
themselves,  and  would  go  on  just  as  they  do  if  conscious- 
ness were  not  at  all  implicated.  Consciousness,  on  this 
view,  is  a  kind  of  by-product  inexpressible  in  terms  of 
force  and  motion,  and  unessential  to  the  molecular  changes 
going  on  in  the  brain. 

Four  years  ago,  I  wrote  thus:  "Do  states  of  conscious- 
ness enter  as  links  into  the  chain  of  antecedence  and 

*  Presidential  address  delivered  before  the  Birmingham  and  Mid- 
land Institute,  October  1,  1877.  Fortnightly  Review,  Nov.  1, 
1877,  p.  607. 


052  FRAGMENTS  OF  SCIENCE. 

sequence,  which  gives  rise  to  bodily  actions?  Speaking 
for  myself,  it  is  certain  that  I  have  no  power  of  imagining 
such  states  interposed  between  the  molecules  of  the  brain, 
and  influencing  the  transference  of  motion  among  the 
molecules.  The  thing  'eludes  all  mental  presentation/ 
Hence  an  iron  strength  seems  to  belong  to  the  logic  which 
claims  for  the  brain  an  automatic  action  uninfluenced  by 
consciousness.  But  it  is,  I  believe,  admitted  by  those  who 
hoM  the  automaton  theory,  that  states  of  consciousness  are 
produced  by  the  motion  of  the  molecules  of  the  brain;  and 
this  production  of  consciousness  by  molecular  motion  is  to 
me  quite  as  unpresentable  to  the  mental  vision  as  the  pro- 
duction of  molecular  motion  by  consciousness.  If  I  reject 
one  result  I  must  reject  both.  /,  hoivever,  reject  neither, 
and  thus  stand  in  the  presence  of  two  Incomprehensibles, 
instead  of  one  Incomprehensible."  Here  I  secede  from 
the  automaton  theory,  though  maintained  by  friends  who 
have  all  my  esteem,  and  fall  back  upon  the  avowal  which 
occurs  with  such  wearisome  iteration  throughout  the  fore- 
going pages;  namely,  my  own  utter  incapacity  to  grasp  the 
problem. 

This  avowal  is  repeated  with  emphasis  in  the  passage  to 
which  Professor  Virchow's  translator  draws  attention. 
What,  I  there  ask,  is  the  causal  connection  between  the 
objective  and  the  subjective — between  molecular  motions 
and  states  of  consciousness?  My  answer  is:  I  do  not  see 
the  connection,  nor  am  I  acquainted  with  anybody  who 
does.  It  is  no  explanation  to  say  that  the  objective  and 
subjective  are  two  sides  of  one  and  the  same  phenomenon. 
Why  should  the  phenomenon  have  two  sides?  This  is  the 
very  core  of  the  difficulty.  There  are  plenty  of  molecular 
motions  which  do  not  exhibit  this  two-sidedness.  Does 
water  think  or  feel  when  it  runs  into  frost-ferns  upon  a 
window  pane?  If  not,  why  should  the  molecular  motion 
of  the  brain  be  yoked  to  this  mysterious  companion — 
consciousness?  We  can  form  a  coherent  picture  of  all  the 
purely  physical  processes — the  stirring  of  the  brain,  the 
thrilling  of  the  nerves,  the  discharging  of  the  muscles,  and 
all  the  subsequent  motions  of  the  organism.  We  are  here 
dealing  with  mechanical  problems  which  are  mentally 
presentable.  But  we  can  form  no  picture  of  the  process 
whereby  consciousness  emerges,  either  as  a  necessary  link, 
or  as  an  accidental  by-product,  of  this  series  of  actions. 


PROFESSOR  VJKUITOW  ANT  EVOLUTION.         653 

The  'reverse  process  of  the  production  of  motion  by  con- 
sciousness is  equally  unpresentable  to  the  mind.  We  are 
here  in  fact  on  the  boundary  line  of  the  intellect,  where 
the  ordinary  canons  of  science  fail  to  extricate  us.  If  we 
are  true  to  these  canons,  we  must  deny  to  subjective  phe- 
nomena all  influence  on  physical  processes.  The  me- 
chanical philosopher,  as  such,  will  never  place  a  state  of 
consciousness  and  a  group  of  molecules  in  the  relation  of 
mover  and  moved.  Observation  proves  them  to  interact; 
but,  in  passing  from  the  one  to  the  other,  we  meet  a  blank 
which  the  logic  of  deduction  is  unable  to  fill.  This,  the 
reader  will  remember,  is  the  conclusion  at  which  I  had 
arrived  more  than  twenty  years  ago.  I  lay  bare  unspar- 
ingly the  central  difficulty  of  the  materialist,  and  tell  him 
that  the  facts  of  observation  which  he  considers  so  simple 
are  "almost  as  difficult  to  be  seized  mentally  as  the  idea 
of  a  soul."  I  go  further,  and  say,  in  effect,  to  those  who 
wish  to  retain  this  idea,  "  If  you  abandon  the  interpreta- 
tions of  grosser  minds,  who  image  the  soul  as  a  Psyche 
which  could  be  thrown  out  of  the  window — an  entity 
which  is  usually  occupied,  we  know  not  how,  among  the 
molecules  of  the  brain,  but  which  on  due  occasion,  such  as 
the  intrusion  of  a  bullet  or  the  blow  of  a  club,  can  fly  away 
into  other  regions  of  space — if,  abandoning  this  heathen 
notion,  you  consent  to  approach  the  subject  in  the  only  way 
in  which  approach  is  possible — if  you  consent  to  make 
your  soul  a  poetic  rendering  of  a  phenomenon  which,  as 
I  have  taken  more  pains  than  anybody  else  to  show  you, 
refuses  the  yoke  of  ordinary  physical  laws — then  I,  for 
one,  would  not  object  to  this  exercise  of  ideality."  I 
say  it  strongly,  but  with  good  temper,  that  the  theologian, 
or  the  defender  of  theology,  who  hacks  and  scourges  me 
for  putting  the  question  in  this  light  is  guilty  of  black 
ingratitude. 

Notwithstanding  the  agreement  thus  far  pointed  out, 
there  are  certain  points  in  Professor  Virchow's  lecture  to 
which  I  should  feel  inclined  to  take  exception.  I  think  it 
was  hardly  necessary  to  associate  the  theory  of  evolution 
with  socialism;  it  may  be  even  questioned  whether  it  was 
correct  to  do  so.  As  Lange  remarks,  the  aim  of  socialism, 
or  of  its  extreme  leaders,  is  to  overthrow  the  existing 
systems  of  government,  and  anything  that  helps  them  to 


654  FRAGMENTS  OF  SCIENCE. 

this  end  is  welcomed,  whether  it  be  atheism  or  papal  in- 
fallibility. For  long  years  the  socialists  saw  church  and 
state  united  against  them,  and  both  were  therefore 
regarded  with  a  common  hatred.  But  no  sooner  does  a 
serious  difference  arise  between  church  and  state,  than  a 
portion  of  the  socialists  begin  immediately  to  dally  with 
the  former.*  The  experience  of  the  last  German  elections 
illustrates  Lange's  position.  Far  nobler  and  truer  to  my 
mind  than  this  fear  of  promoting  socialism  by  a  scientific 
theory  which  the  best  and  soberest  heads  in  the  world  have 
substantially  accepted,  is  the  position  assumed  by  Helm- 
holtz,  who  in  his  "Popular  Lectures"  describes  Darwin's 
theory  as  embracing  "  an  essentially  new  creative  thought " 
(einen  wosentlich  neuen  schopferischen  Gedanken),  and 
who  illustrates  the  greatness  of  this  thought  by  copious 
references  to  the  solutions,  previously  undreamed  of,  which 
it  offers  of  the  enigmas  of  life  and  organization.  He  points 
to  the  clouds  of  error  and  confusion  which  it  has  already 
dispersed,  and  shows  how  the  progress  of  discovery  since 
its  first  enunciation  is  simply  a  record  of  the  approach  of 
the  theory  toward  complete  demonstration.  One  point  in 
this  "  popular"  exposition  deserves  especial  mention  here. 
Helmholtz  refers  to  the  dominant  position  acquired  by 
Germany  in  physiology  and  medicine,  while  other  nations 
have  kept  abreast  of  her  in  the  investigation  of  inorganic 
nature.  He  claims  for  German  men  the  credit  of  pursuing 
with  unflagging  and  self-denying  industry,  with  purely 
ideal  aims,  and  without  any  immediate  prospect  of  practical 
utility,  the  cultivation  of  pure  science.  But  that  which 
has  determined  German  superiority  in  the  fields  referred 
to  was,  in  his  opinion,  something  different  from  this. 
Inquiries  into  the  nature  of  life  are  intimately  connected 
with  psychological  and  ethical  questions;  and  he  claims 
for  his  countrymen  a  greater  fearlessness  of  the  conse- 
quences which  a  full  knowledge  of  the  truth  may  here 
carry  along  with  it,  than  reigns  among  the  inquirers  of 
other  nations.  And  why  is  this  the  case?  "England  and 
France,"  he  says,  "possess  distinguished  investigators — 
men  competent  to  follow  up  and  illustrate  with  vigorous 
energy  the  methods  of  natural  science;  but  they  have 
hitherto  been  compelled  to,  bend  before  social  and  theolog- 

*  "  (ieschichte  des  Materialismus,"  2e  Auflage,  vol.  ii.,  p.  538. 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        655 

ical  prejudices,  and  could  only  utter  their  convictions 
under  the  penalty  of  injuring  their  social  influence  and 
usefulness.  Germany  has  gone  forward  more  courageously. 
She  has  cherished  the  trust,  which  has  never  been  deceived, 
that  complete  truth  carries  with  it  the  antidote  against 
the  bane  and  danger  which  follow  in  the  train  of  half 
knowledge.  A  cheerfully  laborious  and  temperate  people 
— a  people  morally  strong — can  well  afford  to  look  truth 
full  in  the  face.  Nor  are  they  to  be  ruined  by  the  enun- 
ciation of  one-sided  theories,  even  when  these  may  appear 
to  threaten  the  bases  of  society."  These  words  of  lielmr 
holtz  t:re,  in  my  opinion,  wiser  and  more  applicable  to  the 
condition  of  Germany  at  the  present  moment  than  those 
which  express  the  fears  of  Professor  Virchow.  It  will  be 
remembered  that  at  the  time  of  his  lecture  his  chief  anxie- 
ties were  directed  toward  France;  but  France  has  since  that 
time  given  ample  evidence  of  her  ability  to  crush,  not  only 
socialists,  but  anti-socialists,  who  would  impose  on  her  a 
yoke  which  she  refuses  to  bear. 

In  close  connection  with  these  utterances  of  Helmholtz, 
I  place  another  utterance  not  less  noble,  which  I  trust  was 
understood  and  appreciated  by  those  to  whom  it  was  ad- 
dressed. "  If,"  said  the  president  of  the  British  Association 
in  his  opening  address  in  Dublin,  "  we  could  lay  down  be- 
forehand the  precise  limits  of  possible  knowledge,  the 
Eroblem  of  physical  science  would  be  already  half  solved, 
ut  the  question  to  which  the  scientific  explorer  has  often  to 
address  himself  is,  not  merely  whether  he  is  able  to  solve  this 
or  that  problem;  but  whether  he  can  so  far  unravel  the 
tangled  threads  of  the  matter  with  which  he  has  to  deal,  as 
to  weave  them  into  a  definite  problem  at  all.  .  .  .  If  his  eye 
seem  dim,  he  must  look  steadfastly  and  with  hope  into  the 
misty  vision,  until  the  very  clouds  wreathe  themselves 
into  definite  forms.  If  his  ear  seem  dull,  he  must  listen 
patiently  and  with  sympathetic  trust  to  the  intricate  whis- 
perings of  Nature — the  goddess,  as  she  has  been  called,  of 
a  hundred  voices — until  here  and  there  he  can  pick  out  a 
few  simple  notes  to  which  his  own  powers  can  resound.  If, 
then,  at  a  moment  when  he  finds  himself  placed  on  a  pin- 
nacle from  which  he  is  called  upon  to  take  a  perspective 
survey  of  the  range  of  science,  and  to  tell  us  what  'he  can 
see  from  his  vantage  ground;  if  at  such  a  moment,  after 
straining  his  gaze  to  the  very  verge  of  the  horizon,  and 


656  FRAGMENTS  OF  SCIENCE. 

after  describing  the  most  distant  of  well-defined  objects, 
he  should  give  utterance  also  to  some  of  the  subjective 
impressions  which  he  is  conscious  of  receiving  from  regions 
beyond;  if  he  should  depict  possibilities  which  seem  open- 
ing to  his  view;  if  he  should  explain  why  he  thinks  this  a 
mere  blind  alley  and  that  an  open  path;  then  the  fault  and 
the  loss  would  be  alike  oars  if  we  refused  to  listen  calmly, 
and  temperately  to  form  our  own  judgment  on  what  we 
hear}  then  assuredly  it  is  we  who  would  be  committing  the 
error  of  confounding  matters  of  fact  with  matters  of  opin- 
ion, if  we  failed  to  discriminate  between  the  various  ele- 
ments contained  in  such  a  discourse,  and  assumed  that 
they  had  been  all  put  on  the  same  footing." 

While  largely  agreeing  with  him,  I  cannot  quite  accept 
the  setting  in  which  Professor  Virchow  places  the  confess- 
edly abortive  attempts  to  secure  an  experimental  basis  for 
the  doctrine  of  spontaneous  generation.  It  is  not  a  doctrine 
"  so  discredited  "4»liat  some  of  the  scientific  thinkers  of 
England  accept  "  as  the  basis  of  all  their  views  of  life." 
Their  induction  is  by  no  means  thus  limited.  They  have 
on  their  side  more  than  the  "reasonable  probability" 
deemed  sufficient  by  Bishop  Butler  for  practical  guidance 
in  the  gravest  affairs  that  the  members  of  the  solar  system 
which  are  now  discrete  once  formed  a  continuous  mass; 
that  in  the  course  of  untold  ages,  during  which  the  work  of 
condensation,  through  the  waste  of  heat  in  space,  went  on, 
the  planets  were  detached;  and  that  our  present  sun  is  the 
residual  nucleus  of  the  flocculent  or  gaseous  ball  from 
which  the  planets  were  successively  separated.  Life,  as 
we  define  it,  was  not  possible  for  aeons  subsequent  to  this 
separation.  When  and  how  did  it  appear?  I  have  already 
pressed  this  question,  but  have  received  no  answer.*  If, 
with  Professor  Knight,  we  regard  the  Bible  account  of  the 
introduction  of  life  upon  the  earth  as  a  poem,  not  as  a 
statement  of  fact,  where  are  we  to  seek  for  guidance  as  to 
the  fact?  There  does  not  exist  a  barrier  possessing  the 
strength  of  a  cobweb  to  oppose  to  the  hypothesis  which 
ascribes  the  appearance  of  life  to  that  "  potency  of  matter  " 

*  In  the  "  Apology  for  the  Belfast  Address,"  the  question  is  rea- 
out. 


PROFESSOR  VIllCHOW  AND  EVOLUTION.        657 

which  finds  expression  in  natural  evolution.*  This 
hypothesis  is  not  without  its  difficulties,  but  theyjvanish 
when  compared  with  those  which  encumber  its  rivals. 
There  are  various  facts  in  science  obviously  connected,  and 
whose  connections  we  are  unable  to  trace;  but  we  do  not 
think  of  filling  the  gap  between  them  by  the  intrusion  of 
a  separable  spiritual  agent.  In  like  manner  though  we 
are  unable  to  trace  the  course  of  things  from  the  nebula, 
when  there  was  no  life  in  our  sense,  to  the  present  earth 
where  life  abounds,  the  spirit  and  practice  of  science  pro- 
nounce against  the  intrusion  of  an  anthropomorphic 
creator.  Theologians  must  liberate  and  refine  their  con- 
ceptions or  be  prepared  for  the  rejection  of  them  by 
thoughtful  minds.  It  is  they,  not  we,  who  lay  claim  to 
knowledge  never  given  to  man.  Our  refusal  of  the  creative 
hypothesis  is  less  an  assertion  of  knowledge  than  a  protest 
against  the  assumption  of  knowledge  which  must  long,  if 
7iot  always,  lie  beyond  us,  and  the  claim  to  which  is  a 
source  of  perpetual  confusion.  At  the  same  time,  when 
I  look  with  strenuous  gaze  into  the  whole  problem  as  far 
as  my  capacities  allow,  overwhelming  wonder  is  the  pre- 
dominant feeling.  This  wonder  has  come  to  me  from  the 
ages  just  as  much  as  my  understanding,  and  it  has  an* 
equal  right  to  satisfaction.  Hence  I  say,  if,  abandoning 
your  illegitimate  claim  to  knowledge,  you  place,  with  Job, 
your  forehead  in  the  dust  and  acknowledge  the  authorship 
of  this  universe  to  be  past  finding  out — if,  having  made 
this  confession,  and  relinquished  the  views  of  the  mechan- 
ical theologian,  you  desire  for  the  satisfaction  of  feelings 
which  I  admit  to  be,  in  great  part,  those  of  humanity  at 
large,  to  give  ideal  form  to  the  Power  that  moves  all  things 
— it  is  not  by  me  that  you  will  find  objections  raised  to 
this  exercise  of  ideality,  if  it  be  only  consciously  and 
worthily  carried  out. 

Again,  I  think  Professor  Virchow's  position,  in  regard 
to  the  question  of  contagium  animatum,  is  not  altogether 
that  of  true  philosophy.  He  points  to  the  antiquity  of  the 
doctrine.  "It  is  lost/'  he  says,  "  in  the  darkness  of  the 

*"  We  feel  it  an  undeniable  necessity,"  says  Professor  Virchow, 
"  not  to  sever  the  organic  world  from  the  whole,  as  if  it  were  some- 
thing disjoined  from  the  whole."  This  grave  statement  cannot  be 
weakened  by  the  subsequent  pleasantry  regarding  "  Carbon  &  Co." 


658  FRAGMENTS  OF  SCIENCE. 

middle  ages.  We  have  received  this  name  from  our  fore- 
fathers, and  it  already  appears  distinctly  in  the  sixteenth 
century.  We  possess  several  works  of  that  time  which  put 
forward  contagium  animatum  as  a  scientific  doctrine,  with 
the  same  confidence,  with  the  same  sort  of  proof,  with 
which  the  '  Plastidulic  soul'  is  now  set  forth." 

These  speculations  of  our  "forefathers"  will  appeal 
differently  to  different  minds.  By  some  they  will  be 
dismissed  with  a  sneer;  to  others  they  will  appeal  as  proofs 
of  genius  on  the  part  of  those  who  enunciated  them. 
There  are  men,  and  by  no  means  the  minority,  who,  how- 
ever wealthy  in  regard  to  facts,  can  never  rise  into  the 
region  of  principles;  and  they  are  sometimes  intolerant  of 
those  who  can.  They  are  formed  to  plod  meritoriously  on 
the  lower  levels  of  thought,  unpossessed  of  the  pinions 
necessary  to  reach  the  heights.  They  cannot  realize  the 
mental  act — the  act  of  inspiration  it  might  well  be  called 
— by  which  a  man  of  genius,  after  long  pondering  and 
proving,  reaches  a  theoretic  conception  which  unravels 
and  illuminates  the  tangle  of  centuries  of  observation  and 
experiment.  There  are  minds,  it  may  be  said  in  passing, 
who  at  the  present  moment  stand  in  this  relation  to  Mr. 
•Darwin.  For  my  part,  I  should  be  inclined  to  ascribe  to 
penetration  rather  than  to  presumption  the  notion  of  a 
contagium  animatum.  He  who  invented  the  term  ought, 
I  think,  to  be  held  in  esteem;  for  he  had  before  him  tho 
quantity  of  fact,  and  the  measure  of  analogy,  that  would 
justify  a  man  of  genius  in  taking  a  step  so  bold.  "  Never- 
theless," says  Professor  Virchow,  "  no  one  was  able 
throughout  a  long  time  to  discover  these  living  germs  of 
disease.  The  sixteenth  century  did  not  find  them,  nor  did 
the  seventeenth,  nor  the  eighteenth."  But  it  may  be 
urged,  in  reply  to  this,  that  the  theoretic  conjecture  often 
legitimately  comes  first.  It  is  the  forecast  of  genius  which 
anticipates  the  fact  and  constitutes  a  spur  toward  its  dis- 
covery. If,  instead  of  being  a  spur,  the  theoretic  guess 
rendered  men  content  with  imperfect  knowledge,  it  would 
be  a  thing  to  be  deprecated.  But  in  modern  investigation 
this  is  distinctly  not  the  case;  Darwin's  theory,  for  ex- 
ample, like  the  undulatory  theory,  has  been  a  motive 
power  and  not  an  anodyne.  "At  last,"  continues  Profes- 
sor Virchow,  "in  the  nineteenth  century  we  have  begun 
little  by  little  really  to  find  contayia  animata."  So  much 


PROFESSOR  VIRCHOW  AND  EVOLUTION.        659 

the  more  honor,  I  infer,  is  due  to  those  who,  three  cen- 
turies in  advance,  so  put  together  the  facts  and  analogies 
of  contagious  disease  as  to  divine  its  root  and  character. 
Professor  Virchovv  seems  to  deprecate  the  "  obstinacy " 
with  which  this  notion  of  a  contagium  vivum  emerged. 
Here  I  should  not  be  inclined  to  follow  him;  because 
1  do  not  know,  nor  does  he  tell  me,  how  much  the  dis- 
covery of  facts  in  the  nineteenth  century  is  indebted  to 
the  stimulus  derived  from  the  theoretic  discussions  of 
preceding  centuries.  The  genesis  of  scientific  ideas  is 
a  subject  of  profound  interest  and  importance.  He 
would  be  but  a  poor  philosopher  who  would  sever  modern 
chemistry  from  the  efforts  of  the  alchemists,  who  would 
detach  modern  atomic  doctrines  from  the  speculations  of 
Lucretius  and  his  predecessors,  or  who  would  claim  for 
our  present  knowledge  of  contagia  an  origin  altogether  in- 
dependent of  the  efforts  of  our  "forefathers"  to  penetrate 
this  enigma. 

Finally,  I  do  not  know  that  I  should  agree  with 
Professor  Virchow  as  to  what  a  theory  is  or  ought  to  be. 
I  call  a  theory  a  principle  or  conception  of  the  rnind 
which  accounts  for  observed  facts,  and  which  helps  us  to 
look  for  and  predict  facts  not  yet  observed.  Every  new 
discovery  which  fits  into  a  theory  strengthens  it.  The 
theory  is  not  a  thing  complete  from  the  first,  but  a  thing 
which  grows,  as  it  were  asymptotically,  toward  certainty. 
Darwin's  theory,  as  pointed  out  nine  and  ten  years  ago  by 
Helmholtz  and  Hooker,  was  then  exactly  in  this  condition 
of  growth;  and  had  they  to  speak  of  the  subject  to-day 
they  would  be  able  to  announce  an  enormous  strengthen- 
ing of  the  theoretic  fiber.  Fissures  in  continuity  which 
then  existed,  and  which  left  little  hope  of  being  ever 
spanned,  have  been  since  filled  in,  so  that  the  further  the 
theory  is  tested  the  more  fully  does  it  harmonize  with 
progressive  experience  and  discovery.  We  shall  probably 
never  fill  all  the  gaps;  but  this  will  not  prevent  a  pro- 
found belief  in  the  truth  of  the  theory  from  taking  root  in 
the  general  mind.  Much  less  will  it  justify  a  total  denial 
of  the  theory.  The  man  of  science  who  assumes  in  such 
a  case  the  position  of  a  denier  is  sure  to  be  stranded  and 
isolated.  The  proper  attitude,  in  my  opinion,  is  to  give  to 
the  theory  during  the  phases  of  its  growth  as  nearly  as 


6GO  FRAGMENTS  OF  SCIENCE. 

possible  a  proportionate  assent;  and,  if  it  be  a  theory  which 
influences  practice,  our  wisdom  is  to  follow  its  probable 
suggestions  where  more  than  probability  is  for  the  moment 
unattainable.  I  write  thus  with  the  theory  of  contagium 
vivum  more  especially  in  my  mind,  and  must  regret  the 
attitude  of  denial  assumed  by  Professor  Virchow  toward 
that  theory.  "  I  must  beg  my  friend  Klebs  to  pardon 
me,"  he  says,  "  if,  notwithstanding  the  late  advances 
made  by  the  doctrine  of  infectious  fungi,  I  still  persist  in 
my  reserve  so  far  as  to  admit  only  the  fungus  which  is 
really  proved,  while  I  deny  all  other  fungi  so  long  as  they 
are  not  actually  brought  before  me."  Professor  Virchow, 
that  is  to  say,  will  continue  to  deny  the  germ  theory, 
however  great  the  probabilities  on  its  side,  however  numer- 
ous be  the  cases  of  which  it  renders  a  just  account,  until  it 
has  ceased  to  be  a  theory  at  all,  and  has  become  a  congeries 
of  sensible  facts.  Had  he  said,  "  As  long  as  a  single  fungus 
of  disease  remains  to  be  discovered,  it  is  your  bouuden 
duty  to  search  for  it,"  I  should  cordially  agree  with  him. 
But  by  his  unreserved  denial  he  quenches  the  light  of 
probability  which  ought  to  guide  the  practice  of  the 
medical  man.  Both  here  and  in  relation  to  the  theory  of 
evolution  excess  upon  one  side  has  begotten  excess  upon 
the  other. 


CHAPTER  XXXVIII. 

THE   ELECTRIC   LIGHT.* 

THE  SUBJECT  of  this  evening's  discourse  was  proposed  by 
our  late  honorary  secretary.!  That  word  "late"  has  for 
me  its  own  connotations.  It  implies,  among  other  things, 
the  loss  of  a  comrade  by  whose  side  I  have  worked  for 
thirteen  years.  On  the  other  hand,  regret  is  not  without 
its  opposite  in  the  feeling  with  which  I  have  seen  him  rise  by 
sheer  intrinsic  merit,  moral  and  intellectual,  to  the  high- 
est official  position  which  it  is  in  the  power  of  English 
science  to  bestow.  Well,  he,  whose  constant  desire  and 

*  A  discourse  delivered  at  the  Royal  Institution  of  Great  Britain  on 
Friday,  January  17,  1879,  and  introduced  here  as  the  latest  Frag- 
ment. 

f  Mr.  William  Spottis  woode,  late  president  of  the  Royal  Society. 


THE  ELECTRIC  LIGHT.  661 

practice  were  to  promote  the  interests  and  extend  the  use- 
fulness of  this  institution,  thought  that  at  a  time  when  the 
electric  light. occupied  so  much  of  public  attention,  a  few 
sound  notions  regarding  it,  on  the  more  purely  scientific 
side,  might,  to  use  his  own  pithy  expression,  be  "  planted" 
in  the  public  mind.  I  am  here  to-night  with  the  view  of 
trying,  to  the  best  of  my  ability,  to  realize  the  idea  of  our 
friend. 

In  the  year  1800,  Volta  announced  his  immortal  dis- 
covery of  the  pile.  Whetted  to  eagerness  by  the  previous 
conflict  between  him  and  Galvani,  the  scientific  men  of  the 
age  flung  themselves  with  ardor  upon  the  new  discovery, 
repeating  Volta's  experiments,  and  extending  them  in 
many  ways.  The  light  and  heat  of  the  voltaic  circuit 
attracted  marked  attention,  and  in  the  innumerable  tests 
and  trials  to  which  this  question  was  subjected,  the 
utility  of  platinum  and  charcoal  as  means  of  exalting  the 
light  was  on  all  hands  recognized.  Mr.  Children,  with  a 
battery  surpassing  in  strength  all  its  predecessors,  fused 
platinum  wires  eighteen  inches  long,  while  "points  of 
charcoal  produced  a  light  so  vivid  that  the  sunshine,  com- 
pared with  it,  appeared  feeble."*  Such  effects  reached 
their  culmination  when,  in  1808,  through  the  liberality  of 
a  few  members  of  the  Royal  Institution,  Davy  was  enabled 
to  construct  a  battery  of  two  thousand  pairs  of  plates,  with 
which  he  afterward  obtained  calorific  and  luminous  effects 
far  transcending  anything  previously  observed.  The  arc 
of  flame  between  the  carbon  terminals  was  four  inches 
long,  and  by  its  heat  quartz,  sapphire,  magnesia,  and  lime, 
were  melted  like  wax  in  a  candle  flame;  while  fragments  of 
diamond  and  plumbago  rapidly  disappeared  as  if  reduced 
to  vapor,  f 

/      The  first  condition  to  be  fulfilled  in  the  development  of 
heat  and  light  by  the  electric  current  is  that  it  shall  en- 

*  Davy,  "  Chemical  Philosophy,"  p.  110. 

t  In  the  concluding  lecture  at  the  Royal  Institution  in  June,  1810, 
Davy  showed  the  action  of  this  battery.  He  then  fused  iridium,  the 
alloy  of  iridium  and  osmium,  and  other  refractory  substances. 
Philosophical  Magazine,  vol.  xxxv.,  p.  463.  Quetelet  assigns  the 
first  production  of  the  spark  between  coal-points  to  Curtet  in  1802. 
Davy  certainly  in  that  year  showed  the  carbon  light  with  a  battery  of 
150  pairs  of  plates  in  the  theater  of  the  Royal  Institution  ("  Jour. 
Koy.  Inst.,"  vol.  i.,  p.  166). 


662  FRAGMENTS  OF  SCTKNCK. 

counter  and  overcome  resistance.  Flowing  through  a 
perfect  conductor,  no  matter  what  the  strength  of  the 
current  might  be,  neither  heat  nor  light  could  be  developed. 
A  rod  of  unresisting  copper  carries  away  uninjured  and 
unwarmed  an  atmospheric  discharge  competent  to  shiver 
to  splinters  a  resisting  oak.  I  send  the  selfsame  current 
through  a  wire  composed  of  alternate  lengths  of  silver  and 
platinum.  The  silver  offers  little  resistance,  the  platinum 
offers  much.  The  consequence  is  that  the  platinum  is 
raised  to  a  white  heat,  while  the  silver  is  not  visibly 
warmed.  The  same  holds  good  with  regard  to  the  carbon 
terminals  employed  for  the  production  of  the  electric  light. 
The  interval  between  them  offers  a  powerful  resistance  to 
the  passage  of  the  current,  and  it  is  by  the  gathering  up  of 
the  force  necessary  to  burst  across  this  interval  that  the 
voltaic  current  is  able  to  throw  the  carbon  into  that  state 
of  violent  intestine  commotion  which  we  call  heat,  and  to 
which  its  effulgence  is  due.  The  smallest  interval  of  air 
usually  suffices  to  stop  the  current.  But  when  the  carbon 
points  are  first  brought  together  and  then  separated,  there 
occurs  between  them  a  discharge  of  incandescent  matter 
which  carries,  or  may  carry,  the  current  over  a  considerable 
space.  The  light  comes  almost  wholly  from  the  incan- 
descent carbons.  The  space  between  them  is  filled  with  a 
blue  flame  which,  bsing  usually  bent  by  the  earth's  mag- 
netism, receives  the  name  of  the  Voltaic  Arc.* 
-  For  seventy  years,  then,  we  have  been  in  possession  of 
this  transcendent  light  without  applying  it  to  the  illumi- 
nation of  our  streets  and  houses.  Such  applications  sug- 
gested themselves  at  the  outset,  but  there  were  grave 

*  The  part  played  by  resistance  is  strikingly  illustrated  by  the 
deportment  of  silver  and  thallium  when  mixed  together  and  volatil- 
ized in  the  arc.  The  current  first  selects  as  its  carrier  the  most 
volatile  metal,  which  in  this  case  is  thallium.  While  it  continues 
abundant,  the  passage  of  the  current  is  so  free — the  resistance  to  it  is 
so  small — that  the  heat  generated  is  incompetent  to  volatilize  the 
silver.  As  the  thallium  disappears  the  current  is  forced  to  concen- 
trate its  power;  it  presses  the  silver  into  its  service,  and  finally  fills 
the  space  between  the  carbons  with  a  vapor  which,  as  long  as  the 
necessary  resistance  is  absent,  it  is  incompetent  to  produce.  I  have 
on  a  former  occasion  drawn  attention  to  a  danger  which  besets  the 
spectroscopist  when  operating  upon  a  mixture  of  constituents  volatile 
in  different  degrees.  When,  in  1872,  I  first  observed  the  effect  here 
described  had  I  not  known  that  silver  was  present,  I  should  have 
inferred  its  absence. 


THE  ELECTRIC  LIGHT.  663 

difficulties  in  their  way.  The  first  difficulty  arose  from  the 
waste  of  the  carbons,  which  are  dissipated  in  part  by 
ordinary  combustion,  and  in  part  by  the  electric  transfer 
of  matter  from  the  one  carbon  to  the  other.  To  keep  the 
carbons  at  the  proper  distance  asunder  regulators  were 
devised,  the  earliest,  I  believe,  by  Staite,  and  the  most 
successful  by  Duboscq,  Foucault,  and  Serrin,  who  have 
been  succeeded  by  Holmes,  Siemens,  Browning,  Carre, 
Gramme,  Lontin  and  others.  By  such  arrangements  the 
first  difficulty  was  practically  overcome;  but  the  second,  a 
graver  one,  is  probably  inseparable  from  the  construction 
of  the  voltaic  battery.^,  It  arises  from  the  operation  of 
that  inexorable  law  which  throughout  the  material  universe 
demands  an  eye  for  an  eye,  and  a  tooth  for  a  tooth, 
refusing  to  yield  the  faintest  glow  of  heat  or  glimmer  of 
light  without  the  expenditure  of  an  absolutely  equal 
quantity  of  some  other  power.  Hence,  in  practice,  the 
desirability  of  any  transformation  must  depend  upon  the 
value  of  the  product  in  relation  to  that  of  the  power 
expended.  The  metal  zinc  can  be  burned  like  paper;  it 
might  be  ignited  in  a  flame,  but  it  is  possible  to  avoid  the 
introduction  of  all  foreign  heat  and  to  burn  the  zinc  in  air 
of  the  temperature  of  this  room.  This  is  done  by  placing 
zinc  foil  at  the  focus  of  a  concave  mirror,  which  concen- 
trates to  a  point  the  divergent  electric  beam,  but  which 
does  not  warm  the  air.  The  zinc  burns  at  the  focus  with 
a  violet  flame,  and  we  could  readily  determine  the  amount 
of  heat  generated  by  its  combustion.  But  zinc  can  be 
burned  not  only  in  air  but  in  liquids.  It  is  thus  burned  when 
acidulated  water  is  poured  over  it;  it  is  also  thus  burned 
in  the  voltaic  battery.  Here,  however,  to  obtain  the 
oxygen  necessary  for  its  combustion,  the  zinc  has  to  dis- 
lodge the  hydrogen  with  which  the  oxygen  is  combined. 
The  consequence  is  that  the  heat  due  to  the  combustion  of 
the  metal  in  the  liquid  falls  short  of  that  developed  by  its 
combustion  in  air,  by  the  exact  quantity  necessary  to 
separate  the  oxygen  from  the  hydrogen.  Fully  four-fifths 
of  the  total  heat  are  used  up  in  this  molecular  work,  only 
one-fifth  remaining  to  warm  the  battery.  It  is  upon  this 
residue  that  we  must  now  fix  our  attention,  for  it  is  solely 
out  of  it  that  we  manufacture  our  electric  light 

Before   you  are   two  small  voltaic   batteries  of  ten  cells 
each.     The  two  ends  of  one  of  them  are  united  by  a  thick 


664  FRAGMENTS  OF  SCIENCE. 

copper  wire,  while  into  the  circuit  of  the  other  a  thin 
platinum  wire  is  introduced.  The  platinum  glows  with  a 
white  heat,  while  the  copper  wire  is  not  sensibly  warmed. 

Now  an  ounce  of  zinc,  like  an  ounce  of  coal,  produces 
by  its  complete  combustion  in  air  a  constant  quantity  of 
heat.  The  total  heat  developed  by  an  ounce  of  zinc 
through  its  union  with  oxygen  in  the  battery  is  also 
absolutely  invariable.  Let  our  two  batteries,  then,  continue 
in  action  until  an  ounce  of  zinc  in  each  of  them  is  con- 
sumed. In  the  one  case  the  heat  generated  is  purely 
domestic,  being  liberated  on  the  hearth  where  the  fuel  is 
burned,  that  is  to  say  in  the  cells  of  the  battery  itself.  In 
the  other  case,  the  heat  is  in  part  domestic  and  in  part 
foreign — in  part  within  the  battery  and  in  part  outside. 
One  of  the  fundamental  truths  to  be  borne  in  mind  is  that 
the  sum  of  the  foreign  and  domestic — of  the  external  and 
internal — heats  is  fixed  and  invariable.  Hence,  to  have 
heat  outside,  you  must  draw  upon  the  heat  within. 
These  remarks  apply  to  the  electric  light.  By  the  inter- 
mediation of  the  electric  current  the  moderate  warmth  of 
the  battery  is  not  only  carried  away,  but  concentrated  so 
as  to  produce,  at  any  distance  from  its  origin,  a  heat  next 
in  order  to  that  of  the  sun.  The  current  might  therefore 
be  defined  as  the  swift  carrier  of  heat.  Loading  itself  here 
with  invisible  power,  by  a  process  of  transmutation  which 
outstrips  the  dreams  of  the  alchemist,  it  can  discharge  its 
load,  in  the  fraction  of  a  second,  as  light  and  heat,  at  the 
opposite  side  of  the  world. 

Thus,  the  light  and  heat  produced  outside  the  battery 
are  derived  from  the  metallic  fuel  burned  within  the  bat- 
tery; and,  as  zinc  happens  to  be  an  expensive  fuel,  though 
we  have  possessed  the  electric  light  for  more  than  seventy 
years,  it  has  been  too  costly  to  come  into  general  use.  But 
wjthin  these  waljs,  in  the  autumn  of  1831,  Faraday  dis- 
covered  ;i  m-\v  source  of  electricity,  which  we  have  now  to 
investigate.  On  the  table  before  me  lies  a  coil  of  covered 
copper  wire,  with  its  ends  disunited.  I  lift  one  side  of  the 
coil  from  the  table,  and  in  doing  so  exert  the  muscular 
effort  necessary  to  overcome  the  simple  weight  of  the  coil. 
I  unite  its  two  ends  and  repeat  the  experiment.  The 
effort  now  required,  if  accurately  measured,  would  be 
found  greater  than  before.  In  lifting  the  coil  I  cut  the 
lines  of  the  earth's  magnetic  force,  such  cutting,  as  proved 


THE  ELECTRIC  LIGHT.  665 

by  Faraday,  being  always  accompanied,  in  a  closed  con- 
ductor, by  the  production  of  an  "induced"  electric  cur- 
rent which,  as  long  as  the  ends  of  the  coil  remained 
separate,  had  no  circuit  through  which  it  could  pass.  The 
current  here  evoked  subsides  immediately  as  heat;  this 
heat  being  the  exact  equivalent  of  the  excess  of  effort  just 
referred  to  as  over  and  above  that  necessary  to  overcome 
the  simple  weight  of  the  coil.  When  the  coil  is  liberated 
it  falls  back  to  the  table,  and  when  its  ends  are  united  it 
encounters  a  resistance  over  and  above  that  of  the  air.  It 
generates  an  electric  current  opposed  in  direction  to  the 
first,  and  reaches  the  table  with  a  diminished  shock.  The 
amount  of  the  diminution  is  accurately  represented  by  the 
warmth  which  the  momentary  current  develops  in  the 
coil.  Various  devices  were  employed  toexalt  these  induced 
currents,  among  which  the  instruments  of  Pixii,  Clarke, 
and  Saxton  were  long  conspicuous.  Faraday,  indeed,  fore- 
saw that  such  attempts  were  sure  to  be  made;  but  he 
chose  to  leave  them  in  the  hands  of  the  mechanician, 
while  he  himself  pursued  the  deeper  study  of  facts  and 
principles.  "I  have  rather,"  he  writes  in  1831,  "been 
desirous  of  discovering  new  facts  and  new  relations 
dependent  on  magneto-electric  induction,  than  of  exalting 
the  force  of  those  already  obtained;  being  assured  that  the 
latter  would  find  their  full  development  hereafter." 

For  more  than  twenty  years  magneto-electricity  had 
subserved  its  first  and  noblest  purpose  of  augmenting  our 
knowledge  of  the  powers  of  nature.  It  had  been  dis- 
covered and  applied  to  intellectual  ends,  its  application  to 
practical  ends  being  still  unrealized.  The  Drummond 
light  had  raised  thoughts  and  hopes  of  vast  improvements 
in  public  illumination.  Many  inventors  tried  to  obtain  it 
cheaply;  and  in  1853  an  attempt  was  made  to  organize  a 
company  in  Paris  for  the  purpose  of  procuring,  through 
the  decomposition  of  water  by  a  powerful  magneto-electric 
machine  constructed  by  M.  Nollet,  the  oxygen  and 
hydrogen  necessary  for  the  lime  light.  The  experiment 
failed,  but  the  apparatus  by  which  it  was  attempted 
suggested  to  Mr.  Holmes  other  and  more  hopeful  applica- 
tions. Abandoning  the  attempt  to  produce  the  lime 
light,  with  persevering  skill  Holmes  continued  to  improve 
the  apparatus  and  to  augment  its  power,  until  it  wasfinally 
able  to  yield  a  magneto-electric  light  comparable  to  that  of 


666  FRAGMENTS  OF  SCIENCE. 

the  voltaic  battery.  Judged  by  later  knowledge,  this  first 
machine  would  be  considered  cumbrous  and  defective  in 
the  extreme;  but  judged  by  the  light  of  antecedent  events, 
it  marked  a  great  step  forward. 

Faraday  was  profoundly  interested  in  the  growth  of  his 
own  discovery.  The  Elder  Brethren  of  the  Trinity  House 
had  had  the  wisdom  to  make  him  their  "Scientific 
Adviser;"  and  it  is  interesting  to  notice  in  his  reports 
regarding  the  light,  the  mixture  of  enthusiasm  and  caution 
which  characterized  him.  Enthusiasm  was  with  him  a 
motive  power,  guided  and  controlled  by  a  disciplined 
judgment.  He  rode  it  as  a  charger,  holding  it  in  by  a 
Strong  rein.  While  dealing  with  Holmes,  he  states  the 
case  of  the  light  pro  and  con.  He  checks  the  ardor  of  the 
inventor,  and,  as  regards  cost,  rejecting  sanguine  estimates, 
he  insists  over  and  over  again  on  the  necessity  of  continued 
experiment  for  the  solution  of  this  important  question. 
His  matured  opinion  was,  however,  strongly  in  favor  of 
the  light.  With  reference  to  an  experiment  made  at  the 
South  Foreland  on  the  20th  of  April,  1859,  he  thus  ex- 
presses himself:  "The  beauty  of  the  light  was  wonderful. 
At  a  mile  off,  the  apparent  streams  of  light  issuing  from 
the  lantern  were  twice  as  long  as  those  from  the  lower 
lighthouse,  and  apparently  three  or  four  times  as  bright. 
The  horizontal  plane  in  which  they  chiefly  took  their  way 
made  all  above  or  below  it  black.  The  tops  of  the  hills, 
the  churches,  and  the  houses  illuminated  by  it  were  strik- 
ing in  their  effect  upon  the  eye."  Further  on  in  his 
report  he  expresses  himself  thus: — "  In  fulfillment  of  this 
part  of  my  duty,  I  beg  to  state  that,  in  my  opinion,  Pro- 
fessor Holmes  has  practically  established  the  fitness  and 
sufficiency  of  the  magneto-electric  light  for  lighthouse 
purposes,  so  far  as  its  nature  and  management  are  con- 
cerned. The  light  produced  is  powerful  beyond  any  other 
that  I  have  yet  seen  so  applied,  and  in  principle  may  be 
accumulated  to  any  degree;  its  regularity  in  the  lantern  is 
great;  its  management  easy,  and  its  care  there  may  be 
confided  to  attentive  keepers  of  the  ordinary  degree  of. 
intellect  and  knowledge."  Finally,  as  regards  the  conduct 
of  Professor  Holmes  during  these  memorable  experiments, 
it  is  only  fair  to  add  the  following  remark  with  which 
Faraday  closes  the  report  submitted  to  the  Elder  Brethren 
of  the  Trinity  House  on  the  29th  of  April;  1859;  "I 


THE  ELECTRIC  LIGHT.  667 

must  bear  my  testimony,"  he  says,  "to  the  perfect  open- 
ness, candor,  and  honor  of  Professor  Holmes.  He  has 
answered  every  question,  concealed  no  weak  point,  ex- 
plained every  applied  principle,  given  every  reason  for  a 
change  either  in  this  or  that  direction,  during  several 
periods  of  close  questioning,  in  a  manner  that  was  very 
agreeable  to  me,  whose  duty  it  was  to  search  for  real  faults 
or  possible  objections,  in  respect  both  of  the  present  time 
and  the  future."* 

Soon  afterward  the  Elder  Brethren  of  the  Trinity 
House  had  the  intelligent  courage  to  establish  the 
machines  of  Holmes  permanently  at  Dungeness.  where 
the  magneto-electric  light  continued  to  shine  for  many 
years. 

The  magneto-electric  machine  of  the  Alliance  Company 
soon  succeeded  to  that  of  Holmes,  being  in  various  ways  a 
very  marked  improvement  on  the  latter.  Its  currents 
were  stronger  and  its  light  was  brighter  than  those  of  its 
predecessor.  In  it,  moreover,  the  commutator,  the  flash- 
ing and  destruction  of  which  were  sources  of  irregularity 
and  deterioration  in  the  machine  of  Holmes,  was,  at  the 
suggestion  of  M.  Masson,f  entirely  abandoned;  alternating 
currents  instead  of  the  direct  current  being  employed.  M. 
Serrm  modified  his  excellent  lamp  with  the  express  view 
of  enabling  it  to  cope  with  alternating  currents.  During 
the  International  Exhibition  of  1862,  where  the  machine 
was  shown,  M.  Berlioz  offered  to  dispose  of  the  invention 
to  the  Elder  Brethren  of  the  Trinity  House.  They  refer- 
red the  matter  to  Faraday,  and  he  replied  as  follows:  "I 
am  not  aware  that  the  Trinity  House  authorities  have 
advanced  so  far  as  to  be  able  to  decide  whether  they  will 
require  more  magneto-electric  machines,  or  whether,  if 
they  should  require  them,  they  see  reason  to  suppose  the 
means  of  their  supply  in  this  country,  from  the  source 
already  open  to  them, "would  not  be  sufficient.  Therefore 
I  do  not  see  that  at  present  they  want  to  purchase  a 
machine."  Faraday  was  obviously  swayed  by  the  desire  to 
protect  the  interests  of  Holmes,  who  had  borne  the  burden, 
and  heat  which  fall  upon  the  pioneer.  The  Alliance 

*  Holmes'  first  offer  of  his  machine  to  the  Trinity  House  bears 
date  February  2,  1857. 
f  Du  Moucel,  "  1'Electricite,"  August,  1878,  p.  150. 


G68  FRAGMENTS  OF  SCIENCE. 

machines  were  introduced  with  success  at  Cape  la  Hev'e, 
near  Havre;  and  the  Elder  Brethren  of  the  Trinity  House, 
determined  to  have  the  best  available  apparatus,  decided, 
in  1868,  on  the  introduction  of  machines  on  the  Alliance 
principle  into  the  lighthouses  at  Soiiter  Point  and  the 
South  Foreland.  These  machines  were  constructed  by 
Professor  Holmes,  and  they  still  continue  in  operation. 
With  regard,  then,  to  the  application  of  electricity  to 
lighthouse  purposes,  the  course  of  events  was  this:  The 
Dungeness  light  was  introduced  on  January  31,  1862;  the 
light  at  La  Heve  on  December  26,  1863,  or  nearly  two 
years  later.  But  Faraday's  experimental  trial  at  the  South 
Foreland  preceded  the  lighting  of  Dnngeness  by  more  than 
two  years.  The  electric  light  was  afterward  established  at 
Cape  Grisnez.  The  light  was  started  at  Souter  Point  on 
January  11,  1871;  and  at  the  South  Foreland  on  January 
1, 1872.  At  the  Lizard,  which  enjoys  the  newest  and  most 
powerful  development  of  the  electric  light,  it  began  to  shine 
on  January  1,  1878. 

I  have  now  to  revert  to  a  point  of  apparently  small 
moment,  but  which  really  constitutes  an  important  step  in 
the  development  of  this  subject.  I  refer,  to  the  form 

fiven  in  1857  to  the  rotating  armaTure  by  Dr.  Werner 
iemens,  of  Berlin.  Instead  of  employing  coils  wound 
transversely  round  cores  of  iron,  as  in  the  machine  of 
Saxton,  Siemens,  after  giving  a  bar  of  iron  the  proper 
shape,  wound  his  wire  longitudinally  round  it,  and  ob- 
tained thereby  greatly  augmented  effects  between  suitably 
placed  magnetic  poles.  Such  an  armature  is  employed  in 
the  small  magneto- electric  machine  which  I  now  introduce 
to  your  notice,  and  for  which  the  institution  is  indebted  to 
Mr.  Henry  Wilde,  of  Manchester.  There  are  here  sixteen 
permanent  horseshoe  magnets  placed  parallel  to  each 
other,  and  between  their  poles  a  Siemens  armature.  The 
two  ends  of  the  wire  which  surrounds  the  armature  are 
now  disconnected.  In  turning  the  handle  and  causing  the 
armature  to  rotate,  I  simply  overcome  ordinary  mechanical 
friction.  But  the  two  ends  of  the  armature  coil  can  be 
united  in  a  moment,  and  when  this  is  done  I  immediately 
experience  a  greatly  increased  resistance  to  rotation. 
Something  over  and  above  the  ordinary  friction  of  the 
machine  is  now  to  be  overcome,  and  by  the  expenditure  of 


THE  ELECTRIC  LIGHT.  060 

an  additional  amount  of  muscular  force  I  am  able  to  over- 
come it.  The  excess  of  labor  thus  thrown  upon  my  arm 
has  its  exact  equivalent  in  the  electric  currents  generated, 
and  the  heat  produced  by  their  subsidence  in  the  coil  of 
the  armature.  A  portion  of  this  heat  may  be  rendered 
visible  by  connecting  the  two  ends  of  the  coil  with  a  thin 
platinum  wire.  When  the  handle  of  the  machine  is 
rapidly  turned  the  wire  glows,  first  with  a  red  heat,  then 
with  a  white  heat,  and  finally  with  the  heat  of  fusion. 
The  moment  the  wire  melts,  the  circuit  round  the  arma- 
ture is  broken,  an  instant  relief  from  the  labor  thrown 
upon  the  arm  being  the  consequence.  Clearly  realize  the 
equivalent  of  the  heat  here  developed.  Daring  the  period 
of  turning  the  machine  a  certain  amount  of  combustible 
substance  was  oxidized  or  burned  in  the  muscles  of  my  arm. 
Had  it  done  no  external  work,  the  matter  consumed  would 
have  produced  a  definite  amount  of  heat.  Now,  the 
muscular  heat  actually  developed  during  the  rotation  of 
the  machine  fell  short  of  this  definite  amount,  the  missing 
heat  being  reproduced  to  the  last  fraction  in  the  glowing 
platinum  wire  and  the  other  parts  of  the  machine.  Here, 
then,  the  electric  current  intervenes  between  my  muscles 
and  the  generated  heat,  exactly  as  it  did  a  moment  ago 
between  the  voltaic  battery  and  its  generated  heat.  The 
electric  current  is  to  all  intents  and  purposes  a  vehicle 
which  transports  the  heat  both  of  muscle  and  battery  to 
any  distance  from  the  hearth  where  the  fuel  is  consumed. 
Not  only  is  the  current  a  messenger,  but  it  is  also  an 
intensifier  of  magical  power.  The  temperature  of  my 
arm  is,  in  round  numbers,  100  degrees  Fahr.,  and  it  is 
by  the  intensification  of  this  heat  that  one  of  the  most 
refractory  of  metals,  which  requires  a  heat  of  3,600 
degrees  Fahr.  to  fuse  it,  has  been  reduced  to  the  molten 
condition. 

Zinc,  as  I  have  said,  is  a  fuel  far  too  expensive  to  permit 
of  the  electric  light  produced  by  its  combustion  being  used 
for  the  common  purposes  of  life,  and  you  will  readily  per- 
ceive that  the  human  muscles,  or  even  the  muscles  of 
a  horse,  would  be  more  expensive  still.  Here,  however, 
we  can  employ  the  force  of  burning  coal  to  turn  our 
machine,  and  it  is  this  employment  of  our  cheapest  fuel, 
rendered  possible  by  Faraday's  discovery,  which  opens  out 
to  us  the  prospect  of  being  able  to  apply  the  electric  light 
to  public  use. 


670  FRAGMENTS  OF  SCTENCtt. 

In  1866  a  great  step  in  the  intensification  of  induced 
currents,  and  the  consequent  augmentation  of  the  magneto- 
electric  light,  was  taken  by  Mr.  Henry  Wilde.  It  fell  to 
my  lot  to  report  upon  them  to  the  Royal  Society,  but 
before  doing  so  I  took  the  trouble  of  going  to  Manchester 
to  witness  Mr.  Wilde's  experiments.  He  operated  in  this 
way:  starting  from  a  small  machine  like  that  worked  in 
your  presence  a  moment  ago,  he  employed  its  current  to 
excite  an  electro-magnet  of  a  peculiar  shape,  between 
whose  poles  rotated  a  Siemens  armature;*  from  this  arma- 
ture currents  were  ootained  vastly -stronger  than  those 
generated  by  the  small  magneto-electric  machine.  These 
currents  might  have  been  immediately  employed  to  produce 
the  electric  light;  but  instead  of  this  they  were  conducted 
round  a  second  electro-magnet  of  vast  size,  between  whose 
poles  rotated  a  Siemens  armature  of  corresponding 
dimensions.  Three  armatures  therefore  were  involved  in 
this  series  of  operations:  first,  the  armature  of  the  small 
magneto-electric  machine;  secondly,  the  armature  of  the 
first  electro- magnet,  which  was  of  considerable  size;  and, 
thirdly,  the  armature  of  the  second  electro-magnet,  which 
was  of  vast  dimensions.  With  the  currents  drawn  from 
this  third  armature,  Mr.  Wilde  obtained  effects,  both  as 
regards  heat  and  light,  enormously  transcending  those 
previously  known. f 

But  the  discovery  which,  above  all  others,  brought  the 
practical  question  to  the  front  is  now  to  be  considered. 
On  the  4th  of  February,  1867,  a  paper  was  received  by  the 
Royal  Society  from  Dr.  William  Siemens  bearing  the  title, 
"  On  the  Conversion  of  Dynamic  into  Electrical  Force 
without  the  use  of  Permanent  Magnetism."  J  On  the  14th 

*  Page  and  Moigno  had  previously  shown  that  the  magneto-electric 
current  could  produce  powerful  electro-magnets. 

f  Mr.  Wilde's  paper  is  published  in  the  "  Philosophical  Trans- 
actions" for  1867,  p.  89.  My  opinion  regarding  Wilde's  machine 
was  briefly  expressed  in  a  report  to  the  Elder  Brethren  of  the  Trinity 
House  on  May  17,  1866:  "  It  gives  me  pleasure  to  state  that  the 
machine  is  exceedingly  effective,  and  that  it  far  transcends  in  power 
all  other  apparatus  of  the  kind." 

\  A  paper  on  the  same  subject,  by  Dr.  Werner  Siemens,  was  read 
on  January  17,  1867,  before  the  Academy  of  Sciences  in  Berlin.  In 
a  letter  to  Kngineering,  No.  622,  p.  45,  Mr.  Robert  Sabine  states 
that  Professor  Wheatstone's  machines  were  constructed  by  Mr.  Stroh 
in  the  months  of  July  and  August,  1866.  I  do  not  doubt  Mr. 


THE  ELECTRIC  LIGHT.  G?l 

of  February  a  paper  from  Sir  Charles  Wheatstone  was 
received,  bearing  the  title,  "  On  the  Augmentation  of  the 
Power  of  a  Magnet  by  the  reaction  thereon  of  Currents 
induced  by  the  Magnet  itself."  Both  papers,  which  dealt 
with  the  same  discovery,  and  which  were  illustrated  by 
experiments,  were  read  upon  the  same  night,  viz.,  the  14th 
of  February.  It  would  be  difficult  to  find  in  the  whole 
field  of  science  a  more  beautiful  example  of  the  interaction 
of  natural  forces  than  that  set  forth  in  these  two  papers. 
You  can  hardly  find  a  bit  of  iron — you  can  hardly  pick  up 
an  old  horseshoe,  for  example — that  does  not  possess  a 
trace  of  permanent  magnetism;  and  from  such  a  small 
beginning  Siemens  and  Wheatstone  have  taught  us  to  rise 
by  a  series  of  interactions  between  magnet  and  armature  to 
a  magnetic  intensity  previously  unapproached.  Conceive 
the  Siemens  armature  placed  between  the  poles  of  a  suit- 
able electro-magnet.  Suppose  this  latter  to  possess  at 
starting  the  faintest  trace  of  magnetism;  when  the  arma- 
ture rotates,  currents  of  infinitesimal  strength  are  generated 
in  its  coil.  Let  the  ends  of  that  coil  be  connected  with 
the  wire  surrounding  the  electro-magnet.  The  infinitesimal 
current  generated  in  the  armature  will  then  circulate  round 
the  magnet,  augmenting  its  intensity  by  an  infinitesimal 
amount.  The  strengthened  magnet  instantly  reacts  upon 
the  coil  which  feeds  it,  producing  a  current  of  greater 
strength.  This  current  again  passes  round  the  magnet, 
which  immediately  brings  its  enhanced  power  to  bear  upon 
the  coil.  By  this  play  of  mutual  give  and  take  between 
magnet  and  armature,  the  strength  of  the  former  is  raised 
in  a  very  brief  interval  from  almost  nothing  to  complete 
magnetic  saturation.  Such  a  magnet  and  armature  are 
able  to  produce  currents  of  extraordinary  power,  and  if  an 

Sabine's  statement;  still  it  would  be  dangerous  in  the  highest 
degree  to  depart  from  the  canon,  in  asserting  which  Faraday  was 
specially  strenuous,  that  the  date  of  a  discovery  is  the  date  of  its 
publication.  Toward  the  end  of  December,  1866,  Mr.  Alfred  Varley 
also  lodged  a  provisional  specification  (which,  I  believe,  is  a  sealed 
document)  embodying  the  principles  of  the  dynamo-electric  machine, 
but  some  years  'elapsed  before  he  made  anything  public.  His 
brother,  Mr.  Cromwell  Varley,  when  writing  on  this  subject  in  1867, 
does  not  mention  him  (Proc.  Roy.  Soc.,  March  14,  1867).  It  probably 
marks  a  national  trait,  that  sealed  communications,  though  allowed 
in  France,  have  never  been  recognized  by  the  scientific  societies  of 
England. 


(J72  PR  A  GMENTS  0  F  SCIENCE. 

electric  lamp  be  introduced  into  the  common  circuit  of 
magnet  and  armature,  we  can  readily  obtain  a  most  power- 
ful light.*  By  this  discovery,  then,  we  are  enabled  to 
avoid  the  trouble  and  expense  involved  in  the  employment 
of  permanent  magnets;  we  are  also  enabled  to  drop  the 
exciting  magneto-electric  machine,  and  the  duplication  of 
the  electro- magnets.  By  it,  in  short,  the  electric  generator 
is  so  far  simplified,  and  reduced  in  cost,  as  to  enable  elec- 
tricity to  enter  the  lists  as  the  rival  of  our  present  means  of 
illumination. 

Soon  after  the  announcement  of  their  discovery  by 
Siemens  and  Wheatstone,  Mr.  Holmes,  at  the  instance  of 
the  Elder  Brethren  of  the  Trinity  House,  endeavored  to 
turn  this  discovery  to  account  for  lighthouse  purposes. 
Already,  in  the  spring  of  18G9,  he  had  constructed  a 
machine  which,  though  hampered  with  defects,  exhibited 
extraordinary  power.  The  light  was  developed  in  the 
focus  of  a  dioptric  apparatus  placed  on  the  Trinity  Wharf 
at  Blackwall,  and  witnessed  by  the  Elder  Brethren,  Mr. 
Douglass,  and  myself,  from  an  observatory  at  Charlton,  on 
the  opposite  side  of  the  Thames.  Falling  upon  the 
suspended  haze,  the  light  illuminated  the  atmosphere  for 
miles  all  round.  Anything  so  sunlike  in  splendor  had  not, 
I  imagine,  been  previously  witnessed.  The  apparatus  of 
Holmes,  however,  was  rapidly  distanced  by  the  safer  and 
more  powerful  machines  of  Siemens  and  Gramme. 

As  regards  lighthouse  illumination,  the  next  step  forward 
was  taken  by  the  Elder  Brethren  of  the  Trinity  House  in 
1876-77.  Having  previously  decided  on  the  establishment 
of  the  electric  light  at  the  Lizard  in  Cornwall,  they 
instituted,  at  the  time  referred  to,  an  elaborate  series  of 
comparative  experiments  wherein  the  machines  of  Holmes, 
of  the  Alliance  Company,  of  Siemens,  and  of  Gramme, 
were  pitted  against  each  other.  The  Siemens  and  the 
Gramme  machines  delivered  direct  currents,  while  those 
of  Holmes  and  the  Alliance  Company  delivered  alternating 
currents.  The  light  of  the  latter  was  of  the  same  intensity 
in  all  azimuths;  that  of  the  former  was  different  in 
different  azimuths,  the  discharge  being  so  regulated  as  to 
yield  a  gush  of  light  of  special  intensity  in  one  direction. 

*  In  1867  Mr.  Ladd  introduced  the  modification  of  dividing  the 
armature  into  two  separate  coils,  one  of  which  fed  the  electro-magnets, 
while  the  other  yielded  the  induced  currents. 


THE  ELECTRIC  LIGHT.  673 

The  following  table  gives  in  standard  candles  the  perform- 
ance of  the  respective  machines:  * 

Name  of  Machines.  Maximums.  Minimum. 

Holmes 1,523  1,523 

Alliance 1,953  1,953 

Gramme  (No.  1)  .         .         .         .  6,663  4,016 

Gramme  (No.  2)  .         .         .         .  6,663  4,016 

Siemens  (Large)           .         .         .  14,818  8,932 

Siemens  (Small,  No.  1)        .         .  5.539  3,339 

Siemens  (Small,  No.  2)       .         .  6,864  4,138 

Two  Holmes'  Coupled         .         .  2,811  2,811 

Two  Gramme's  (Nos.  land  2)       .  11,396  6,869 

Two  Siemens' (Nos.  1  and  2)       .  14,134  8,520 

These  determinations  were  made  with  extreme  care  and 
accuracy  by  Mr.  Douglass,  the  engineer-in-chief,  and  Mr. 
Ay  res,  the  assistant  engineer  of  the  Trinity  House.  It  is 
practically  impossible  to  compare  photometrically  and 
directly  the  flame  of  the  candle  with  these  sunlike  lights. 
A  light  of  intermediate  intensity — that  of  the  six- wick 
Trinity  oil  lamp — was  therefore  in  the  first  instance  com- 
pared with  the  electric  light.  The  candle  power  of  the  oil 
lamp  being  afterward  determined,  the  intensity  of  the 
electric  light  became  known.  The  numbers  given  in  the 
table  prove  the  superiority  of  the  Alliance  machine  over 
that  of  Holmes.  They  prove  the  great  superiority  both  of 
the  Gramme  machine  and  of  the  small  Siemens  machine 
over  the  Alliance.  The  large  Siemens  machine  is  shown 
to  yield  a  light  far  exceeding  all  the  others,  while  the 
coupling  of  two  Grammes,  or  of  two  Siemens  together, 
here  effected  for  the  first  time,  was  followed  by  a  very 
great  augmentation  of  the  light,  rising  in  the  one  case 
from  6,663  candles  to  11,396,  and  in  the  other  case  from 
6,864  candles  to  14,134.  Where  the  arc  is  single  and  the 
external  resistance  small,  great  advantages  attach  to  the 
Siemens  light.  After  this  contest,  which  was  conducted 

*  Observations  from  the  sea  on  the  night  of  November  21,  1876, 
made  the  Gramme  and  small  Siemens  practically  equal  to  the 
Alliance.  But  the  photometric  observations,  in  which  the  external 
resistance  was  abolished,  and  previous  to  which  the  light-keepers  had 
become  more  skilled  in  the  management  of  the  direct  current  showed 
the  differences  recorded  in  the  table.  A  close  inspection  of  these 
powerful  lights  at  the  South  Foreland  caused  my  face  to  peel,  as  if  it 
had  been,  irritated  by  an  Alpine  sun. 


674  FRAGMENTS  OF  SCIENCE. 

throughout  in   the  most  amicable    manner,  Siemens  ma- 
chines of  type  No.  2  were  chosen  for  the  Lizard.* 

We  have  machines  capable  of  sustaining  a  single  light, 
and  also  machines  capable  of  sustaining  several  lights. 
The  Gramme  machine,  for  example,  which  ignites  the 
Jablochkoff  candles  on  the  Thames  Embankment  and  at 
the  Holboni  Viaduct,  delivers  four  currents,  each  passing 
through  its  own  circuit.  In  each  circuit  are  five  lamps 
through  which  the  current  belonging  to  the  circuit  passes 
in  succession.  The  lights  correspond  to  so  many  resisting 
spaces,  over  which,  as  already  explained,  the  current  has 
to  leap;  the  force  which  accomplishes  the  leap  being  that 
which  produces  the  light.  Whether  the  current  is  to  be 
competent  to  pass  through  five  lamps  in  succession,  or  to 
sustain  only  a  single  lamp,  depends  entirely  upon  the  will 
and  skill  of  the  maker  of  the  machine.  He  lias,  tp  guide 
him,  definite  laws  laid  down  by  Ohm  half  a  century  ago,  by 
which  he  must  abide. 

Ohm  has  taught  us  how  to  arrange  the  elements  of  a  vol- 
taic battery  so  as  to  augment  indefinitely  its  electro-motive 
force — that  force,  namely,  which  urges  the  current  forward 
and  enables  it  to  surmount  external  obstacles.  We  have 
only  to  link  the  cells  together  so  that  the  current  generated 
by  each  cell  shall  pass  through  all  the  others,  and  add  its 
electro-motive  force  to  that  of  all  the  others.  We  increase, 
it  is  true,  at  the  same  time,  the  resistance  of  the  battery, 
diminishing  thereby  the  quantity  of  the  current  from  each 
cell,  but  we  augment  the  power  of  the  integrated  current 
to  overcome  external  hindrances.  The  resistance  of  the 
battery  itself  may,  indeed,  be  rendered  so  great  that  the 
external  resistance  shall  vanish  in  comparison.  What  is 
here  said  regarding  the  voltaic  battery  is  equally  true  of 
magneto-electric  machines,  If  we  wish  our  current  to 
leap  over  five  intervals,  and  produce  five  lights  in 
succession,  we  must  invoke  a  sufficient  electro-motive 
force.  This  is  done  through  multiplying,  by  the  use  of 
thin  wires,  the  convolutions  of  the  rotating  armature  as,  a 
moment  ago,  we  augmented  the  cells  of  our  voltaic  battery. 
Each  additional  convolution,  like  each  additional  cell,  adds 

*  As  the  result  of  a  recent  trial  by  Mr.  Schwendler,  they  have  been 
also  chosen  for  India. 


THE  ELECTRIC  LIGHT.  675 

its  electro-motive  force  to  that  of  all  the  others;  and 
though  it  also  adds  its  resistance,  thereby  diminishing  the 
quantity  of  current  contributed  by  each  convolution,  the 
integrated  current  becomes  endowed  with  the  power  of 
leaping  across  the  successive  spaces  necessary  for  the  pro- 
duction of  a  series  of  lights  in  its  course.  The  current  is, 
as  it  were,  rendered  at  once  thinner  and  more  piercing  by 
the  simultaneous  addition  of  internal  resistance  and  electro- 
motive power.  The  machines,  on  the  other  hand,  which 
produce  only  a  single  light  have  a  small  internal  resistance 
associated  with  a  small  electro-motive  force.  In  such 
machines  the  wire  of  the  rotating  armature  is  compara- 
tively short  and  thick,  copper  riband  instead  of  wire  being 
commonly  employed.  Such  machines  deliver  a  large 
quantity  of  electricity  of  low  tension — in  other  words,  of 
low  leaping  power.  Hence,  though  competent  when  their 
power  is  converged  upon  a  single  interval,  to  produce  one 
splendid  light,  their  currents  are  unable  to  force  a  passage 
when  the  number  of  intervals  is  increased.  Thus,  by 
augmenting  the  convolutions  of  our  machines  we  sacrifice 
quantity  and  gain  electro-motive  force;  while  by  lessening 
the  number  of  the  convolutions  we  sacrifice  electro- 
motive force  and  gain  quantity.  Whether  we  ought  to 
choose  the  one  form  of  machine  or  the  other  depends 
entirely  upon  the  external  work  the  machine  has  to  per- 
form. If  the  object  be  to  obtain  a  single  light  of  great 
splendor,  machines  of  low  resistance  and  large  quantity 
must  be  employed.  If  we  want  to  obtain  in  the  same  cir- 
cuit several  lights  of  moderate  intensity,  machines  of  high 
internal  resistance  and  of  correspondingly  high  electro- 
motive power  must  be  invoked. 

When  a  coil  of  covered  wire  surrounds  a  bar  of  iron,  the 
two  ends  of  the  coil  being  connected  together,  every 
alteration  of  the  magnetism  of  the  bar  is  accompanied  by 
the  development  of  an  induced  current  in  the  coil.  The 
current  is  only  excited  during  the  period  of  magnetic 
change.  No  matter  how  strong  or  how  weak  the  mag- 
netism of  the  bar  may  be,  as  long  as  its  condition  remains 
permanent  no  current  is  developed.  Conceive,  then,  the 
pole  of  a  magnet  placed  near  one  end  of  the  bar  to  be 
moved  along  it  toward  the  other  end.  During  the  time  of 
the  pole's  motion  there  will  be  an  incessant  change  in  the 
magnetism  of  the  bar,  and  accompanying  this  change  we 


676  FRAGMENTS  OF  SCIENCE. 

shall  have  an  induced  current  in  the  surrounding  coil.  If, 
instead  of  moving  the  magnet,  we  move  the  bar  and  its 
surrounding  coil  past  the  magnetic  pole,  a  similar  alter- 
ation of  the  magnetism  of  the  bar  will  occur,  and  a  similar 
current  will  be  induced  in  the  coil.  You  have  here  the 
fundamental  conception  which  led  M.  Gramme  to  the 
construction  of  his  beautiful  machine.*  He  aimed  at 
giving  continuous  motion  to  such  a  bar  as  we  have  here 
described;  and  for  this  purpose  he  bent  it  into  a  continuous 
ring,  which,  bv  a  suitable  mechanism,  he  caused  to  rotate 
rapidly  close  to  the  poles  of  a  horseshoe  magnet.  The 
direction  of  the  current  varied  with  the  motion  and  with 
the  character  of  the  influencing  pole.  The  result  was  that 
the  currents  in  the  two  semicircles  of  the  coil  surrounding 
the  ring  flowed  in  opposite  directions.  But  it  was  easy,  by 
the  mechanical  arrangement  called  a  commutator,  to 
gather  up  the  currents  and  cause  them  to  flow  in  the  same 
direction.  The  first  machines  of  Gramme,  therefore, 
furnished  direct  currents,  similar  to  those  yielded  by  the 
voltaic  pile.  M.  Gramme  subsequently  so  modified  his 
machine  as  to  produce  alternating  currents.  Such  alter- 
nating machines  are  employed  to  produce  the  lights  now 
exhibited  on  the  Holborn  Viaduct  and  Thames  Embank- 
ment. 

Another  machine  of  great  alleged  merit  is  that  of  M. 
Lontin.  It  resembles  in  shape  a  toothed  iron  wheel,  the 
teeth  being  used  as  cores,  round  which  are  wound  coils  of 
copper  wire.  The  wheel  is  caused  to  rotate  between  the 
opposite  poles  of  powerful  electro-magnets.  On  passing 
each  pole  the  core  or  tooth  is  strongly  magnetized,  and 
instantly  evokes  in  its  surrounding  coil  an  induced  current 
of  corresponding  strength.  The  currents  excited  in  ap- 
proaching to  and  retreating  from  a  pole,  and  in  passing 
different  poles,  move  in  opposite  directions,  but  by  means 
of  a  commutator  these  conflicting  electric  streams  are 
gathered  up  and  caused  to  flow  in  a  common  bed.  The 
bobbins,  in  which  the  currents  are  induced,  can  be  so 
increased  in  number  as  to  augment  indefinitely  the  power 
of  the  machine.  To  excite  his  electro-magnets,  M.  Lontin 
applies  the  principle  of  Mr.  Wilde.  A  small  machine 

*  "  Comptes'Rendus,"  1871,  p.  176.  See  also  Gaugain  on  the 
Gramme  machine,  "Ann.  de  Chem.  et  de  Phys.,"  vol.  xxviii.,  p.  334. 


THE  ELECTRIC  LIGHT.  677 

furnishes  a  direct  current,  which  is  carried  round  the 
electro-magnets  of  a  second  and  larger  machine.  Wilde's 
principle,  it  may  be  added,  is  also  applied  on  the  Thames 
Embankment  and  the  Holborn  Viaduct;  a  small  Gramme 
machine  being  used  in  each  case  to  excite  the  electro- 
magnets of  the  large  one. 

The  Farmer- Wallace  machine  is  also  an  apparatus  of 
great  power.  It  consists  of  a  combination  of  bobbins  for 
induced  currents,  and  of  inducing  electro-magnets,  the 
latter  being  excited  by  the  method  discovered  by  Siemens 
and  Wheatstone.  In  the  machines  intended  for  the 
production  of  the  electric  light,  the  electro-motive  force  is 
so  great  as  to  permit  of  the  introduction  of  several  lights 
in  the  same  circuit.  A  peculiarly  novel  feature  of  the 
Farmer- Wallace  system  is  the  shape  of  the  carbons.  In- 
stead of  rods,  two  large  plates  of  carbons  with  beveled 
edges  are  employed,  one  above  the  other.  The  electric 
discharge  passes  from  edge  to  edge,  and  shifts  its  position 
according  as  the  carbon  is  dissipated.  The  duration  of  the 
light  in  this  case  far  exceeds  that  obtainable  with  rods.  I 
have  myself  seen  four  of  these  lights  in  the  same  circuit 
in  Mr.  Ladd's  workshop  in  the  City,  and  they  are 
now,  I  believe,  employed  at  the  Liverpool  Street  Station 
of  the  Metropolitan  Railway.  The  Farmer-Wallace 
"  quantity  machine  "  pours  forth  a  flood  of  electricity  of 
low  tension.  It  is  unable  to  cross  the  interval  necessary 
for  the  production  of  the  electric  light,  but  it  can  fuse 
thick  copper  wires.  When  sent  through  a  short  bar  of 
iridium,  this  refractory  metal  emits  a  light  of  extraordinary 
splendor.* 

The  machine  of  M.  de  Meritens,  which  he  has  gener- 
ously brought  over  from  Paris  for  our  instruction,  is  the 
newest  of  all.  In  its  construction  he  falls  back  upon  the 
principle  of  the  magneto-electric  machine,  employing 
permanent  magnets  as  the  exciters  of  the  induced  currents. 
Using  the  magnets  of  the  Alliance  Company,  by  a  skillful 
disposition  of  his  bobbins,  M.  de  Meritens  produces  with 
eight  magnets  a  light  equal  to  that  produced  by  forty  mag- 
nets in  the  Alliance  machines.  While  the  space  occupied 
is  only  one-fifth,  the  cost  is  little  more  than  one-fourth 

*The  iridium  light  was  shown  by  Mr.  Ladd.  It  brilliantly  illu- 
minated the  theater  of  the  Royal  Institution. 


678  FRAGMENTS  OF  SCIENCM. 

of  the  latter.  In  the  de  Meritens  machine  the  commu- 
tator is  abolished.  The  internal  heat  is  hardly  sensible, 
and  the  absorption  of  power,  in  relation  to  the  effects 
produced,  is  small.  With  his  larger  machines  M.  de 
Meritens  maintains  a  considerable  number  of  lights  in  the 
same  circuit.  * 

In  relation  to  this  subject,  inventors  fall  into  two  classes, 
the  contrivers  of  regulators  and  the  constructors  of 
machines.  M.  Rapieff  has  hitherto  belonged  to  inventors 
of  the  first  class,  but  I  have  reason  to  know  that  lie  is 
engaged  on  a  machine  which,  when  complete,  will  place 
him  in  the  other  class  also.  Instead  of  two  single  carbon 
rods,  M.  Rapieff  employs  two  pairs  of  rods,  each  pair 
forming  a  V.  The  light  is  produced  at  the  common  junc- 
tion of  the  four  carbons.  The  device  for  regulating  the 
light  is  of  the  simplest  character.  At  the  bottom  of  the 
stand  which  supports  the  carbons  are  two  small  electro- 
magnets. One  of  them,  when  the  current  passes,  draws 
the  carbons  together,  and  in  so  doing  throws  itself  out  of 
circuit,leaving  the  control  of  the  light  to  the  other.  The 
carbons  are  caused  to  approach  each  other  by  a  descending 
weight,  which  acts  in  conjunction  with  the  electro-magnet. 
Through  the  liberality  of  the  proprietors  of  the  Times, 
every  facility  has  been  given  to  M.  Rapieff  to  develop  and 
simplify  his  invention  at  Printing  House  Square.  The 
illumination  of  the  press-room,  which  I  had  the  pleasure  of 
witnessing,  under  the  guidance  of  M.  Rapieff  himself,  is 
extremely  effectual  and  agreeable  to  the  eye.  There  are,  I 
believe,  five  lamps  in  the  same  circuit,  and  the  regulators 
are  so  devised  that  the  extinction  of  any  lamp  does  not 
compromise  the  action  of  the  others.  M.  Rapieff  has  lately 
improved  his  regulator. 

Many  other  inventors  might  here  be  named,  and  fresh 
ones  are  daily  crowding  in.  Mr.  Werdermann  has  been 
long  known  in  connection  with  this  subject.  Employing 
as  negative  carbon  a  disc,  and  as  positive  carbon  a  rod,  he 
has,  I  am  assured,  obtained  very  satisfactory  results.  The 
small  resistances  brought  into  play  by  his  minute  arcs 
enable  Mr.  Werdermann  to  introduce  a  number  of  lamps 

*The  small  machine  transforms  one-and-a-quarter  horse-power 
into  heat  and  light,  yielding  about  1,900  candles;  the  large  machine 
transforms  five-horse  power,  yielding  about  9,000  candles. 


ELKCTRK  LIGHT.  ($79 

into  a  circuit  traversed  by  a  current  of  only  moderate 
electro-motive  power.  M.  Keynier  is  also  the  inventor  of 
a  very  beautiful  little  lamp,  in  which  the  point  of  a  thin 
carbon  rod,  properly  adjusted,  is  caused  to  touch  the  cir- 
cumference of  a  carbon  wheel  which  rotates  underneath 
the  point.  The  light  is  developed  at  the  place  of  contact 
of  rod  and  wheel.  One  of  the  last  steps,  though  I  am 
informed  not  quite  the  last,  in  the  improvement  of 
regulators  is  this:  The  positive  carbon  wastes  more  pro- 
fusely than  the  negative,  and  this  is  alleged  to  be  due  to 
the  greater  heat  of  the  former.  It  occurred  to  Mr. 
William  Siemens  to  chill  the  negative  artificially,  with  the 
view  of  diminishing  or  wholly  preventing  its  waste.  This 
he  accomplishes  by  making  the  negative  pole  a  hollow  cone 
of  copper,  and  by  ingeniously  discharging  a  small  jet  of 
cold  water  against  the  interior  of  the  cone.  His  negative 
copper  is  thus  caused  to  remain  fixed  in  space,  for  it  is  not 
dissipated,  the  positive  carbon  only  needing  control.  I 
have  seen  this  lamp  in  action,  and  can  bear  witness  to  its 
success. 

I  might  go  on  to  other  inventions,  achieved  or  pro- 
jected. Indeed,  there  is  something  bewildering  in  the  recent 
rush  of  constructive  talent  into  this  domain  of  applied 
electricity.  The  question  and  its  prospects  are  modified 
from  day  to  day,  a  steady  advance  being  made  toward  the 
improvement  both  of  machines  and  regulators.  With 
regard  to  our  public  lighting,  I  strongly  lean  to  the  opinion 
that  the  electric  light  will  at  no  distant  day  triumph  over 
gas.  I  am  not  so  sure  that  it  will  do  so  in  our  private 
houses.  As,  however,  I  am  anxious  to  avoid  dropping  a 
word  here  that  could  influence  the  share  market  in  the 
slightest  degree,  I  limit  myself  to  this  general  statement  of 
opinion. 

To  one  inventor  in  particular  belongs  the  honor  of  the 
idea,  and  the  realization  of  the  idea,  of  causing  the  carbon 
rods  to  burn  away  like  a  candle.  It  is  needless  to  say  that 
I  here  refer  to  the  young  Russian  officer,  M.  Jablochkoff. 
He  sets  two  carbon  rods  upright  at  a  small  distance  apart, 
and  fills  the  space  between  them  with  an  insulating  sub- 
stance like  plaster  of  Paris.  The  carbon  rods  are  fixed  in 
metallic  holders.  A  momentary  contact  is  established 
between  the  two  carbons  by  a  little  cross-piece  of  the  same 
substance  placed  horizontally  from  top  to  top.  This  cross- 


680  F11AQMKNT8  0V  SCtKNCtt. 

piece  is  immediately  dissipated  or  removed  by  the  current, 
the  passage  of  which  ouce  established  is  afterward  main- 
tained. The  carbons  gradually  waste,  while  the  substance 
between  them  melts  like  the  wax  of  a  candle.  The  com* 
parison,  however,  only  holds  good  for  the  act  of  melting; 
for,  as  regards  the  current,  the  insulating  plaster  is  practi- 
cally inert.  Indeed,  as  proved  by  M.  Rapieff  and  Mr. 
Wilde,  the  plaster  may  be  dispensed  with  altogether,  the 
current  passing  from  point  to  point  between  the  nuked 
carbons.  M.  de  Meritens  has  recently  brought  out  a  new 
candle,  in  which  the  plaster  is  abandoned,  while  between 
the  two  principal  carbons  is  placed  a  third  insulated  rod  of 
the  same  material.  With  the  small  de  Meritens  machine 
two  of  these  candles  can  be  lighted  before  you;  they 
produce  a  very  brilliant  light.  *  In  the  Jablochkoff  candle 
it  is  necessary  that  the  carbons  should  be  consumed  at  the 
same  rate.  Hence  the  necessity  for  alternating  currents 
by  which  this  equal  consumption  is  secured.  It  will  be 
seen  that  M.  Jablochkoff  has  abolished  regulators 
altogether,  introducing  the  candle  principle  in  their 
stead.  In  my  judgment,  the  performance  of  the  Jabloch- 
koff candle  on  the  Thames  Embank  men't  and  the  Hoi  born 
Viaduct  is  highly  creditable,  notwithstanding  a  consider- 
able waste  of  light  toward  the  sky.  The  Jablochkoff  lamps, 
it  may  be  added,  would  be  more  effective  in  a  street,  where 
their  light  would  be  scattered  abroad  by  the  adjacent 
houses,  than  in  the  positions  which  they  now  occupy  in 
London. 

It  was  my  custom  some  years  ago,  whenever  I  needed  a 
new  and  complicated  instrument,  to  sit  down  beside  its 
proposed  constructor,  and  to  talk  the  matter  over  with 
him.  The  study  of  the  inventor's  mind  which  this  habit 
opened  out  was  always  of  the  highest  interest  to  me.  I 
particularly  well  remember  the  impression  made  upon  me 
on  such  occasions  by  the  late  Mr.  Darker,  a  philosophical 
instrument  maker  in  Lambeth.  This  man's  life  was  a 
struggle,  and  the  reason  of  it  was  not  far  to  seek.  No 
matter  how  commercially  lucrative  the  work  upon  which 

*  The  machine  of  M.  de  Meritens  and  the  Farmer- Wallace  machine 
were  worked  by  an  excellent  gas-engine,  lent  for  the  occasion  by  the 
Messrs.  Cro«sley,  of  Manchester.  The  Siemens  machine  was  worked 
by  steam. 


THE  ELECTRIC  LIGHT.  681 

he  was  engaged  might  be,  he  would  instantly  turn  aside 
from  it  to  seize  and  realize  the  ideas  of  a  scientific  man. 
He  had  an  inventor's  power,  and  an  inventor's  delight  in 
its  exercise.  The  late  Mr.  Becker  possessed  the  same 
power  in  a  very  considerable  degree.  On  the  Continent, 
Froment,  13reguet,  Sauerwald,  and  others  might  be  men- 
tioned as  eminent  instances  of  ability  of  this  kind.  Such 
minds  resemble  a  liquid  on  the  point  of  crystallization. 
Stirred  by  a  hint,  crystals  of  constructive  thought  imme- 
diately shoot  through  them.  That  Mr.  Edison  possesses 
this  intuitive  power  in  no  common  measure,  is  proved  by 
what  he  has  already  accomplished.  He  has  the  penetra- 
tion to  seize  the  relationship  of  facts  and  principles,  and 
the  art  to  reduce  them  to  novel  and  concrete  combina- 
tions. Hence,  though  he  has  thus  far  accomplished 
nothing  that  we  can  recognize  as  new  in  relation  to  the 
electric  light,  an  adverse  opinion  as  to  his  ability  to  solve 
the  complicated  problem  on  which  he  is  engaged  would  be 
unwarranted. 

I"  will  endeavor  to  illustrate  in  a  simple  manner  Mr. 
Edison's  alleged  mode  of  electric  illumination,  taking 
ad  vantage  of  what  Ohm  has  taught  us  regarding  the  laws 
of  the  current,  and  what  Joule  has  taught  us  regarding 
the  relation  of  resistance  to  the  development  of  light  and 
heat.  From  one  end  of  a  voltaic  battery  runs  a  wire, 
dividing  at  a  certain  point  into  two  branches,  which  re- 
unite in  a  single  wire  connected  with  the  other  end  of  the 
battery.  From  the  positive  end  of  the  battery  the 
current  passes  first  through  the  single  wu-e  to  the 
point  of  junction,  where  it  divides  itself  between  the 
branches  according  to  a  well-known  law.  If  _the  branches 
be  equally  resistant,  the  current  divides  itself  equally 
between  them.  If  one  branch  be  less  resistant  than  the 
other,  more  than  half  the  current  will  choose  the  freer 
path.  The  strict  law  is  that  the  quantity  of  current  is 
inversely  proportional  to  the  resistance.  A  clear  image  of 
the  process  is  derived  from  the  deportment  of  water.  When 
a  river  meets  an  island  it  divides,  passing  right  and  left  of 
the  obstacle,  and  afterward  reuniting.  If  the  two  branch 
beds  be  equal  in  depth,  width,  and  inclination,  the  water 
will  divide  itself  equally  between  them.  If  they  be  un- 
equal, the  larger  quantity  of  water  will  flow  through  the 
more  open  course.  And,  as  in  the  case  of  the  water  we 


688  PR  A  GMENTS 

may  have  an  indefinite  number  of  islands,  producing  an 
indefinite  subdivision  of  the  trunk  stream,  so  in  the  case  of 
ele.-.tricity  we  may  have  instead  of  two  branches,  any  number 
of  branches,  the  current  dividing  itself  among  them,  in 
accordance  with  the  law  which  fixes  the  relation  of  flow  to 
resistance. 

Let  us  apply  this  knowledge.  Suppose  an  insulated 
copper  rod,  which  we  may  call  an  "electric  main,"  to  be 
laid  down  along  one  of  our  streets,  say  along  the  Strand. 
Let  this  rod  be  connected  with  one  end  of  a  powerful  vol- 
taic battery,  a  good  metallic  connection  being  established 
between  the  other  end  of  the  battery  and  the  water-pipes 
under  the  street.  As  long  as  the  electric  main  continues 
unconnected  with  the  water-pipes,  the  circuit  is  incomplete 
and  no  current  will  flow;  but  if  any  part  of  the  main, 
however  distant  from  the  battery,  be  connected  with  the 
adjacent  water-pipes,  the  circuit  will  be  completed  and 
the  current  will  flow.  Supposing  our  battery  to  be  at 
Charing  Cross,  and  our  rod  of  copper  to  be  tapped  oppo- 
site Somerset  House,  a  wire  can  be  carried  from  the  j-od 
into  the  building,  and  the  current  passing  through  the 
wire  may  be  subdivided  into  any  number  of  subordinate 
branches,  which  reunite  afterward  and  return  through  the 
water-pipes  to  the  battery.  The  branch  currents  may  be 
employed  to  raise  to  vivid  incandescence  a  refractory  metal 
like  iridium  or  one  of  its  alloys.  Instead  of  being  tapped  at 
one  point,  our  main  may  be  tapped  at  one  hundred  points. 
The  current  will  divide  in  strict  accordance  with  law,  its 
power  to  produce  light  being  solely  limited  by  its  strength. 
The  process  of  division  closely  resembles  the  circulation  of 
the  blood;  the  electric  main  carrying  the  outgoing  current 
representing  a  great  artery,  the  water-pipes  carrying  the 
return  current  representing  a  great  vein,  while  the  inter- 
mediate branches  represent  the  various  vessels  by  which 
the  blood  is  distributed  through  the  system.  This,  if  I 
understand  aright,  is  Mr.  Edison's  proposed  mode  of  illu- 
mination. The  electric  force  is  at  hand.  Metals  suffici- 
ently refractory  to  bear  being  raised  to  vivid  incandescence 
are  also  at  hand.  The  principles  which  regulate  the  divi- 
sion of  the  current  and  the  development  of  its  light  and 
heat  are  perfectly  well  known.  There  is  no  room  for  a 
"discovery,"  in  the  scientific  sense  of  the  term,  but  there 
is  ample  room  for  the  exercise  of  that  mechanical  ingenuity 


THE  WLKGTRtC  LIGHT.  683 

which  has  given  us  the  sewing  machine  and  so  many  other 
useful  inventions.  Knowing  something  of  the  intricacy  of 
the  practical  problem,  I  should  certainly  prefer  seeing  it  in 
Mr.  Edison's  hands  to  having  it  in  mine.* 

It  is  sometimes  stated  as  a  recommendation  to  the  elec- 
tric light,  that  it  is  light  without  heat;  but  to  disprove 
this,  it  is  only  necessary  to  point  to  the  experiments  of 
Davy,  which  show  that  the  heat  of  the  voltaic  arc  tran- 
scends that  of  any  other  terrestrial  source.  The  emission 
from  the  carbon  points  is  capable  of  accurate  analysis.  To 
simplify  the  subject,  we  will  take  the  case  of  a  platinum 
wire  at  first  slightly  warmed  by  the  current,  and  then 
gradually  raised  to  a  white  heat.  '  When  first  warmed,  the 
wire  sends  forth  rays  which  have  no  power  on  the  optic 
nerve.  They  are  what  we  call  invisible  rays;  and  not 
until  the  temperature  of  the  wire  has  reached  nearly  1,000 
degrees  Fahr.,  does  it  begin  to  glow  with  a  faint,  red  light. 
The  rays  which  it  emits  prior  to  redness  are  all  invisible 
rays  which  can  warm  the  hand  but  cannot  excite  vision. 
When  the  temperature  of  the  wire  is  raised  to  whiteness, 
these  dark  rays  not  only  persist,  but  they  are  enormously 
augmented  in  intensity.  They  constitute  about  95  per 
cent,  of  the  total  radiation  from  the  white-hot  platinum 
wire.  They  make  up  nearly  90  per  cent,  of  the  emission 
from  a  brilliant  electric  light.  You  can  by  no  means  have 
the  light  of  the  carbons  without  this  invisible  emission  as 
an  accompaniment.  The  visible  radiation  is  as  it  were,  built 
upon  the  invisible  as  its  necessary  foundation. 

It  is  easy  to  illustrate  the  growth  in  intensity  of  these 
invisible  rays  as  the  visible  ones  enter  the  radiation  and 
augment  in  power.  The  transparency  of  the  elementary 
gases  and  metalloids — of  oxygen,  hydrogen,  nitrogen, 
chlorine,  iodine,  bromine,  sulphur,  phosphorus,  and  even 
of  carbon,  for  the  invisible  heat  rays  is  extraordinary. 
Dissolved  in  a  proper  vehicle,  iodine  cuts  the  visible 
radiation  sharply  off,  but  allows  the  invisible  free  trans- 
mission. By  dissolving  iodine  in  sulphur,  Professor  Dewar 
has  recently  added  to  the  number  of  our  effectual  ray- 
filters.  The  mixture  may  be  made  as  black  as  pitch  for 

•  *More  than  thirty  years  ago  the  radiation  from  incandescent  plati- 
num was  admirably  investigated  by  Dr.  Draper  of  New  York. 


684  FRAGMENTS  OF  SCTKNVE. 

the  visible,  wliile  remaining  transparent  for  the  invisible 
rays.  By  such  filters  it  is  possible  to  detach  the  invisible 
rays  from  the  total  radiation,  and  to  watch  their  augmenta- 
tion as  the  light  increases.  Expressing  the  radiation  from 
a  platinum  wire  when  it  first  feels  warm  to  the  touch — 
when,  therefore,  all  its  rays  are  invisible — by  the  number 
1,  the  invisible  radiation  from  the  same  wire  raised  to  a 
white  heat  may  be  500  or  more.*  It  is  not,  then,  by  the 
diminution  or  tniusformation  of  the  non-luminous  emission 
that  we  obtain  the  luminous;  the  heat  rays  maintain  their 
ground  as  the  necessary  antecedents  and  companions  of 
the  light  rays.  When  detached  and  concentrated,  these 
powerful  heat  rays  can  produce  all  the  effects  ascribed  to 
the  mirrors  of  Archimedes  at  the  siege  of  Syracuse.  While 
incompetent  to  produce  the  faintest  glimmer  of  light,  or 
to  affect  the  most  delicate  air-thermometer,  they  will 
inflame  paper,  burn  up  wood,  and  even  ignite  combustible 
metals.  When  they  impinge  upon  a  metal  refractory 
enough  to  bear  their  shock  without  fusion,  they  can  raise 
it  to  a  heat  so  white  and  luminous  as  to  yield,  when 
analyzed,  all  the  colors  of  the  spectrum.  In  this  way  the 
dark  rays  emitted  by  the  incandescent  carbons  are  converted 
into  light  rays  of  all  colors.  Still,  so  powerless  are  these 
invisible  rays  to  excite  vision,  that  the  eye  has  been 
placed  at  a  focus  competent  to  raise  platinum  foil  to  bright 
redness  without  experiencing  any  visual  impression. 
Light  for  light,  no  doubt,  the  amount  of  heat  imparted  by 
the  incandescent  carbons  to  the  air  is  far  less  than  that 
imparted  by  gas  flames.  It  is  less,  because  of  the  smaller 
size  of  the  carbons,  and  of  the  comparative  smallness  of 
the  quantity  of  fuel  consumed  in  a  given  time.  It  is  also 
less  because  the  air  cannot  penetrate  the  carbons  as  it  pen- 
etrates a  flame.  The  temperature  of  the  flame  is  lowered 
by  the  admixture  of  a  gas  which  constitutes  four-fifths  of 
our  atmosphere,  and  which,  while  it  appropriates  and 
diffuses  the  heat,  does  not  aid  in  the  combustion;  and  this 
lowering  of  the  temperature  by  the  inert  atmospheric 
nitrogen  renders  necessary  the  combustion  of  a  greater 
amount  of  gas  to  produce  the  necessary  light.  In  fact, 
though  the  statement  may  appear  paradoxical,  it  is  entirely 
because  of  its  enormous  actual  temperature  that  the 

*See  article  "  Radiation." 


THE  EL  EC  TRIG  LIGHT.  685 

electric  light  seems  so  cool.  It  is  this  temperature  that 
renders  the  proportion  of  luminous  to  non-luminous  heat 
greater  in  the  electric  light  than  in  our  brightest  flames. 
The  electric  light,  moreover,  requires  no  air  to  sustain  it. 
It  glows  in  the  most  perfect  air  vacuum.  Its  light  and 
heat  are  therefore  not  purchased  at  the  expense  of  the 
vitalizing  constituent  of  the  atmosphere. 

Two  orders  of  minds  have  been  implicated  in  the  develop- 
ment of  this  subject;  first,  the  investigator  and  discoverer, 
whose  object  is  purely  scientific,  and  who  cares  little  for 
practical  ends;  secondly,  the  practical  mechanician,  whose 
object  is  mainly  industrial.  It  would  be  easy,  and  prob- 
ably in  many  cases  true  to  say  that  the  one  wants  to  gain 
knowledge,  while  the  other  wishes  to  make  money;  but  I 
am  persuaded  that  the  mechanician  not  unfrequently 
merges  the  hope  of  profit  in  the  love  of  his  work.  Mem- 
bers of  each  of  these  classes  are  sometimes  scornful  toward 
those  of  the  other.  There  is,  for  example,  something- 
superb  in  the  disdain  with  which  Cuvier  hands  over  the 
discoveries  of  pure  science  to  those  who  apply  them: 
"  Your  grand  practical  achievements  are  only  the  easy 
application  of  truths  not  sought  with  a  practical  intent — 
truths  which  their  discoverers  pursued  for  their  own  sake, 
impelled  solely  by  an  ardor  for  knowledge.  Those  who 
turned  them  into  practice  could  not  have  discovered  them, 
while  those  who  discovered  them  had  neither  the  time  nor 
the  inclination  to  pursue  them  to  a  practical  result.  Your 
rising  workshops,  your  peopled  colonies,  your  vessels  which 
furrow  the  seas;  this  abundance,  this  luxury,  this  tumult," 
— "  this  commotion/'  he  would  have  added,  were  he  now 
alive,  "  regarding  the  electric  light" — ''all  come  from 
discoveries  in  science,  though  all  remain  strange  to  them. 
The  day  that  a  discovery  enters  the  market  they  abandon 
it;  it  concerns  them  no  more." 

In  writing  thus,  Cuvier  probably  did  not  sufficiently 
take  into  account  the  reaction  of  the  applications  of 
science  upon  science  itself.  The  improvement  of  an  old 
instrument  or  the  invention  of  a  new  one  is  often 
tantamount  to  an  enlargement  and  refinement  of  the  senses 
of  the  scientific  investigator.  Beyond  this,  the  amelio- 
ration of  the  community  is  also  an  object  worthy  of  the 
best  efforts  of  the  human  brain.  Still,  assuredly  it  is  vyell 
and  wise  for  a  nation  to  bear  in  mind  that  those  practical 


686  FRAGMENTS  OF  SCIENCE. 

applications  which  strike  the  public  eye,  and  excite  public 
admiration,  are  the  outgrowth  of  long  antecedent  labors 
begun,  continued,  and  ended,  under  the  operation  of  a 
purely  intellectual  stimulus.  "  Few,"  says  Pasteur,  "  seem 
to  comprehend  the  real  origin  of  the  marvels  of  industry  and 
the  wealth  of  nations.  I  need  no  other  proof  of  this  than 
the  frequent  employment  in  lectures,  speeches,  and  official 
language  of  the  erroneous  expression,  'applied  science.' 
A  statesman  of  the  greatest  talent  stated  some  time  ago 
that  in  our  day  the  reign  of  theoretic  science  had  rightly 
yielded  place  to  that  of  applied  science.  Nothing,  I 
venture  to  say,  could  be  more  dangerous,  even  to  practical 
life,  than  the  consequences  which  might  flow  from  these 
words.  They  show  the  imperious  necessity  of  a  reform  in 
our  higher  education.  There  exists  no  category  of  sciences 
to  which  the  name  of  'applied  science"  could  be  given. 
We  have  science  and  the  applications  of  science  which  are 
united  as  tree  and  fruit." 

A  final  reflection  is  here  suggested.  We  have  among 
us  a  small  cohort  of  social  regenerators — men  of  high 
thoughts  and  aspirations — who  would  place  the  operations 
of  the  scientific  mind  under  the  control  of  a  hierarchy 
which  should  dictate  to  the  man  of  science  the  course  that 
he  ought  to  pursue.  How  this  hierarchy  is  to  get  its 
wisdom  they  do  not  explain.  They  decry  and  denounce 
scientific  theories;  they  scorn  all  reference  to  ether,  and 
atpms,  and  molecules,  as  subjects  lying  far  apart  from  the 
world's  needs;  and  yet  such  ultra-sensible  conceptions  are 
often  the  spur  to  the  greatest  discoveries.  The  source,  in 
fact,  from  which  the  true  natural  philosopher  derives 
inspiration  and  unifying  power  is  essentially  ideal.  Fara- 
day lived  in  this  ideal  world.  Nearly  half  a  century  ago, 
when  he  first  obtained  a  spark  from  the  magnet,  an  Oxford 
don  expressed  regret  that  such  a  discovery  should  have  been 
made,  as  it  placed  a  new  and  facile  implement  in  the  hands 
of  the  incendiary.  To  regret,  a  Comtist  hierarchy  would 
have  probably  added  repression,  sending  Faraday  back  to 
his  bookbinder's  bench  as  a  more  dignified  and  practical 
sphere  of  action  than  peddling  with  a  magnet.  And  yet  it 
is  Faraday's  spark  which  now  shines  upon  our  coasts,  and 
promises  to  illuminate  our  streets,  halls,  quays,  squares, 
warehouses,  and,  perhaps  at  no  distant  day,  our  homes, 

THE  END. 


BURT'S   LIBRARY 


OB  THE 


WORLD'S  BEST  BOOKS. 


A  seines  which  will  include  the  standard  works  of  the  world's 
literature.  The  books  will  be  neatly  and  durably  bound,  printed  on 
good  paper,  in  large,  clear  type,  uniform  in  all  respects  with  this 
volume.  The  text  will  be  in  every  case  thoroughly  reliable  and 
unabridged,  hence  meeting  equally  the  needs  of  the  student  and 
general  reader.  Indexes,  biographical  sketches  and  explanatory  notes 
will  be  given  wJiere  these  are  likely  to  prove  of  value  and  interest. 
All  who  have  at  heart  the  best  interests  of  literature,  and  would 
further  the  spread  of  a  taste  for  the  world's  classics,  will  welcome 
the  appearance  of  this  series,  which  will  place  a  complete,  rich  and 
uniform  library  of  the  highest  cJia,racter  within  the  reach  of  all. 


of  ttoe  EWorld's  §e$t 


The  Essays  or  Counsels  Civil  and  Moral  of  Francis  Bacon. 
First  published  in  1597,  and  as  he  left  them  newly  written  and  pub- 
lished in  1625.  Including  also  his  Apophthegms,  Elegant  Sentences, 
and  Wisdom  of  the  Ancienjts.  With  an  introduction  by  HENRY 
MORLEY,  LL.D.,  Professor  of  English  Literature  at  University  Col- 
lege, London.  Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

They  (Bacon's  Essays)  contain  the  condensed  wisdom  gathered  during  the 
whole  long  life-time  of  one  of  the  mightiest  minds  of  modern  times.—  Frank 
PqfMHU. 

Vanity  Fair.  A  Novel  Without  a  Hero.  By  WILLIAM  MAKE 
PEACE  THACKERAY.  Portrait,  12mo,  cloth,  gilt  top,  $1.00. 

As  a  whole  the  book  is  full  of  quiet  sarcasm  and  severe  rebuke.  It  is  replete 
with  humor  and  morality,  and  rivets  attention  to  the  end  by  the  vivid  reality 
of  all  the  persons  and  scenes.—  From  "A  Manual  of  English  Literature  "  by  T.  B. 
Shaw. 

Other  Worlds  Than  Ours.  The  plurality  of  worlds  studied 
under  the  light  of  recent  scientific  researches.  By  RICHARD  A. 
PROCTOR.  With  an  introductory  note  by  FRANK  PARSONS.  Portrait. 
Cloth,  gilt  top,  $1.00. 

Like  Huxley  and  Tyndall,  Mr.  Proctor  sees  the  poetry  of  his  subject  and 
knows  how  to  bring  the  largest  truths  within  the  comprehension  of  a  child, 
and  make  the  deepest  researches  as  interesting  to  the  general  reader  as  a 
novel.  —  Frank  Parsons. 

The  Fifteen  Decisive  Battles  of  the  World,  from  Marathon  to 
Waterloo.  By  E.  S.  CREASY,  M.A.,  Professor  of  Ancient  and  Mod- 
ern History  in  University  College,  London;  late  Fellow  of  King's 
College,  Cambridge.  With  an  introductory  note  by  FRANK  PAR- 
SONS. Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

So  vivid  are  his  descriptions  that  one  feels  as  though  he  were  present  at  the 
scene  himself,  listening  to  the  counsels  of  the  generals,  hearing  the  tread  of 
marching  columns,  watching  the  gleaming  spears  and  bayonets,  armies  of  in- 
fantry, charging  cavalry,  breach,  rally  and  retreat,  deafened  with  the  roar  of 
batteries,  saddened  by  the  death  of  friends,  and  flushed  with  triumph  ;  and  at 
last  the  reader  lays  the  book  away  exhausted  with  the  rush  of  feeling  through 
his  heart.—  Frank  Parson*. 

The  Essays  of  Elia.  By  CHARLES  LAMB.  With  an  introduc- 
tion and  notes  by  Alfred  Ainger,  and  a  Biographical  Sketch  of 
Charles  Lamb,  by  Henry  Morley.  Portrait.  12mo,  cloth,  gilt  top, 
$1.00. 

The  Essays  of  Elia  have  been  characterized  as  the  "  finest  things  for  humor, 
taste,  penetration  and  vivacity  which  have  appeared  since  the  days  of  Mon- 
taigne." In  his  bits  of  criticism  Charles  Lamb  shows  a  most  delicate  and 
acute  critical  faculty  ;  in  his  few  poems,  much  grace  and  sweetness,  but  first 
and  foremost,  he  is  an  essayist  of  rare  power.  The  refined  wit.  genuine  pleas- 
antry, deep  and  tender  pathos,  and  subtle  discrimination  of  his  essays,  are  un- 
excelled by  any  compositions  in  the  language.  —  Robert  Thorne. 

Essays.  By  RALPH  WALDO  EMERSON.  First  and  second  series. 
Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

He  exercised  a  great  power  over  men  ;  he  brought  them  wide  comfort,  and 
to  him  more  than  to  any  man  of  his  time  belongs  the  glory  of  having  taught 
them  that  life  was  worth  the  living.—  From  the  "  Optimism  of  Emerson,"  by  W. 
F.  Dana. 

For  sale  by  all  Booksellers,  or  will  be  sent  post-paid  on  receipt  of  price,  by  (fie  pub- 
Usher*  A..  1»  Ji  VRT,  66  -R«««{e  Street,  New  Tori?, 


gutf  * 


0! 


A  Thousand  Miles  Up  The  Nile.  By  AMELIA  B.  EDWARDS. 
Portrait.  12ino,  illustrated,  cloth,  gilt  top,  $1.00. 

The  Mill  on  the  Floss.  By  GEORGE  ELIOT.  Portrait.  12mo, 
cloth,  gilt  top,  $1.00. 

This  is  a  charming  story  of  middle-class  English  life,  for  which  George  Eliot 
is  justly  celebrated.  .  .  .  "The  Mill  on  the  Floss"  commends  itself  strongly 
to  the  reader  by  its  fine  analyses  of  motives,  its  vivid  force  in  description  and 
its  quality  as  a  work  of  literary  art. 

The  Adventures  of  Oliver  Twist.  By  CHARLES  DICKENS. 
Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

It  is  in  the  English  parochial  work  -house  that  we  first  meet  Oliver,  and  his 
Buffering!  while  under  the  charge  of  that  benign  creature,  Mr.  Bumble,  are 
alone  sufficient  to  secure  for  him  our  warmest  sympathy.  .  .  .  There  is 
passion  and  feeling  in  every  page  of  the  book,  and  it  can  be  read;  not  alone 
once,  but  again  and  again,  with  renewed  delight. 

The  Holy  Roman  Empire.  By  JAMES  BRYCE,  D.  C.  L.  Portrait. 
12mo,  cloth,  gilt  top,  $1.00. 

"  The  Holy  Roman  Empire  "  is  a  work  of  great  learning,  and  is  universally 
conceded  to  show  a  high  degree  of  historical  power,  though  written  at  an 
early  age  it  immediately  established  the  reputation  of  the  distinguished  author 
as  one  of  the  most  profound  thinkers  of  the  century,  and  has  steadily  grown 
into  the  highest  favor  with  scholars. 

Daniel  Deronda.  By  GEORGE  ELIOT.  Portrait,  12mo,  cloth, 
gilt  top,  $1.00. 

"  Daniel  Deronda  "  is  a  love  story,  but  at  the  same  time  a  treasure-house  of 
Information  regarding  the  manners,  customs,  and  traditions  of  the  Hebrew 
race.  It  belongs  to  the  enduring  literature  of  the  age,  durable,  not  for  the 
fashionableness  of  its  pattern,  but  for  the  texture  of  its  stuff. 

Corinne;  or,  Italy.  By  MADAME  DE  STAEL.  Portrait.  12mo, 
cloth,  gilt  top,  $1.00. 

"  Corinne,"  the  success  of  which  was  instant,  and  won  for  the  author  a  really 
European  reputation,  is  a  love  story  which  emphasizes  strength  and  nobility 
of  character  and  purity  of  life.  The  scene  of  the  tale  is  laid  principally  in  Italy 

nd  interspersed  throughout  the  narrative  are  vivid  glimpses  of  Italian  scenery, 

ife,  manners,  and  its  historical  and  literary  remains. 


fi 

The  Divine  Comedy ;  or,  Vision  of  Hell,  Purgatory  and  Para- 
dise. By  DANTE  ALIGIIIERI.  Translated  by  the  Rev.  Henry 
Francis  Gary,  M.  A.  Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

The  llivina  Comedia  is  one  of  the  grandest  monuments  of  human  genius, 
with  the  epics  of  Homer  and  Milton  it  forms  a  supreme  trinity  of  poems,  which 
have  summed  up  the  spirit  of  great  eras  of  civilization  and  formed  the  educa- 
tion of  succeeding  centuries. 

Consuelo.  By  GEORGE  SAND.  Portrait.  12mo,  cloth,  gilt  top, 
$1.00. 

In  the  character  of  Consuelo  Madame  Sand  has  pictured  for  us  a  woman  as 
chaste,  as  noble  and  as  lovable  as  any  in  all  fiction.  .  .  .  "  Consuelo  "  is  an 
ideal  romance  of  remarkable  power  and  fascination  and  it  will  long  live  a 
monument  to  its  author's  genius. 

For  sale  by  all  Booksellers,  or  u'Ul  be  sent  post-paid  on  receipt  of  price,  by  the  pub 
Usher,  A.  X.  SUJtT,  66  Reade  St.,  New  York. 


ot  the 


Westward  Ho !  or,  The  Voyages  and  Adventures  of  Sir 
Amyas  Leigh,  Knight.  By  CHARLES  KINGSLEY.  Portrait.  12mo, 
cloth,  gilt  top,  $1.00. 

"  Westward  Ho  1 "  is  one  of  the  most  vigorous,  powerful,  and  fascinating  of 
novels.  It  is  strong  and  graphic  in  its  portraiture,  Intense  and  dramatic  in  its 
diversified  coloring.  The  nervous  and  effective  style,  the  skillful  blending  of 
the  manifold  portraits  into  one  comprehensive  picture,  are  among  the  merits 
which  have  made  this  Kingsley's  greatest  work.—  Frederic  Mynon  Cooper. 

The  Pilgrim's  Progress.  By  JOHN  BUNYAN,  with  a  life  of  Bun 
yan  by  James  Anthony  Froude.  Portrait.  12rno,  cloth,  gilt  top, 
$1.00. 

No  other  book  except  the  Bible  has  jtone  through  so  many  editions  and  at 
tained  to  so  wide  a  popularity  in  all  languages  as  "  The  Pilgrim's  Progress." 
...  It  narrates  the  struggles,  the  experiences,  and  the  trials  of  a  Christian 
In  his  passage  from  a  life  of  sin  to  everlasting  felicity  :  and  it  abounds  with 
those  little  inimitable  touches  of  natural  feeling  and  description  which  have 
placed  its  author  among  the  most  picturesque  of  writers.  .  .  .  Bunyan  may 
truly  be  called  the  prince  of  allegorists,  and  he  is  also  the  most  perfect  repre- 
sentative of  the  plain,  vigorous,  idiomatic,  and  sometimes  picturesque  and 
poetical  language  of  the  common  people. —  Taken  from  "A  Manual  of  Eiiylixh 
Literature,"  by  T.  B.  Shaw. 

Self-Help,  with  Illustrations  of  Character,  Conduct,  and  Per- 
severance. By  SAMUEL  SMILES.  Portrait.  12mo,  cloth,  gilt  top, 
$1.00. 

"  Self-Help"  is  a  book  which  helps  and  stimulates  men  to  elevate  and  improve 
themselves.  It  teaches  them  that  the  humblest  person  who  sets  before  his  fel- 
lows an  example  of  industry,  sobriety,  and  upright  honesty  of  purpose  in  life, 
has  a  present  as  well  as  a  future  influence  upon  the  well-being  of  his  country. 
.  .  .  Hundreds  of  its  terse  and  happy  phrases  have  become  the  common 
property  of  mankind,  and  it  has  been  already  translated  into  four  or  five  of  the 
European  languages.—  Frederic  Mynon  Cooper. 

Jane  Eyre.  By  CHARLOTTE  BRONTE.  Portrait.  12mo,  cloth, 
gilt  top,  $1.00. 

Few  novels  have  gained  such  immediate  popularity  as  was  accorded  to  "Jane 
Eyre."  This  was  doubtless  due  in  part  to  the  freshness  and  vigor  of  mind  it 
evinced  ;  but  it  was  obtained  not  so  much  by  these  qualities  as  by  the  frequent 
dealings  in  moral  paradox,  and  by  the  hardihood  of  its  assaults  upon  the  preju- 
dices of  proper  people.  Throughout  the  tale  the  author  exhibits  a  perception 
of  character  and  the  power  of  delineating  it,  which  is,  considering  her  youth, 
remarkable.—  Frederic  Mynon  Cooper. 

The  Moonstone.  A  Novel.  By  WILKIE  COLLINS.  Portrait. 
12mo,  cloth,  gilt  top,  $1.00. 

Like  the  generality  of  his  romances,  the  interest  of  "The  Moonstone"  depends 
chiefly  upon  the  development  of  a  plot  whose  systematic  intricacies  pique  the 
cun>  >sity  until  the  last  moment,  and  upon  the  concealment  of  a  mystery  which 
haffles  and  defies  solution  until  it  shall  have  contributed  to  no  end  of  cross 
purposes  and  caused  a  prodigious  amount  of  incertitude  and  wretchedness.— 
Frederic  Mynon  Cooper. 

For  sale  by  all  Booksellers,  or  trill  be  sent  post-paid  on  receipt  of  price,  bt/  the  pub- 
lisher, A.  L,.  BVRT,  66  Jteade  Street,  New  York. 


o!  ttte 


Faust.  By  JOHANN  WOLFGANG  VON  GOETHE.  Complete  in  two 
parts.  Translated  by  Anna  Swanwick.  Portrait.  Cloth,  gilt  top, 

Deeper  meanings  are  discovered  with  every  reading,  and  familiarity  does 
not  cause  it  to  grow  trite,  but  ever  the  more  strongly  to  lay  hold  on  the  soul 
with  the  irresistible  fascination  of  an  eternal  problem  and  the  charm  of  an 
endless  variety.—  Ilobert  T/ierne. 

The  Sketch-  Book  of  Geoffrey  Crayon,  Gent.  By  WASHINGTON 
IRVING.  With  an  introductory  note  by  FKANK  PARSONS.  Portrait 
Cloth,  gilt  top,  $1.00. 

The  book  is  refined,  poetical  and  picturesque,  full  of  quaint  humor,  exquis 
Ite  feeling,  and  a  thorough  knowledge  of  human  nature.—  Frank  Parsons. 

Lorna  Doone.  A  Romance  of  Exmoor.  By  R.  D.  BLACKMORE. 
12mo,  cloth,  gilt  top,  $1.00. 

These  wonderfully  reproduced  scenes,  and  the  men  and  women  with  whom 
they  are  peopled,  and  finally  the  beautiful  language  in  which  the  narrative  is 
set  forth,  unite  to  make  a  delightful,  and,  what  is  more,  a  wholesome,  invigo- 
rating, inspiring  book.—  E.  8.  flawes. 

Hypatia,  or  New  Foes  with  an  Old  Face.  By  CHARLES  KINGS 
LEY,  P.S.A.,  F.L.S.  Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

The  plot  is  well  developed,  the  characters  are  vigorously  drawn,  and  the 
scenes  and  incidents  show  great  dramatic  power,  while  the  language  and 
word-painting  are  exquisite.  The  book  holds  throughout,  with  a  firm  grasp, 
our  sympathy  and  interest,  Kingsley  being  one  of  the  very  few  who  have  suc- 
ceeded in  throwing  a  strong  human  interest  into  a  historical  novel.—  Botert 
Thorne. 

Romola.  By  GEORGE  ELIOT,  Portrait  12mo,  cloth,  gilt  top, 
$1.00. 

George  Eliot  is  admitted  by  thoughtful  persons  to  have  been  endowed  with 
one  of  the  greatest  minds  of  this  century.  .  .  .  Romola,  which  is  one  of 
her  earlier  works,  is  also  one  of  the  most  popular.  The  movement  is  so  rapid, 
and  the  situations  are  so  dramatic,  that  the  interest  never  flags  ;  .  .  .  the 
book  has  nowhere  the  air  of  tiresome  preaching,  but  it  stands  the  test  of  a 
great  novel—  it  may  be  read  again  and  again  with  pleasure.—  E.  S.  Hawes. 

The  Data  of  Ethics.  By  HERBERT  SPENCER.  Portrait.  12mo, 
cloth,  gilt  top,  $1.00. 

Herbert  Spencer  is  the  foremost  name  in  the  philosophic  literature  of  the 
world.  He  is  the  Shakespeare  of  science.  He  has  a  grander  grasp  of  knowl- 
edge and  more  perfect  conscious  correspondence  with  the  external  universe 
than  any  other  human  being  who  ever  looked  wonderingly  out  i»to  the  starry 
depths  ;  and  his  few  errors  flow  from  an  over-anxiety  to  exert  his  splendid 
power  of  making  beautiful  generalizations.  Plato  and  Spencer  are  brothers. 
Plato  would  have  done  what  Spencer  has  had  he  lived  in  the  nineteenth  cen 
tury.—  From  "  The  World's  Best  Hooks,"  by  Frank  Parsons. 

The  Origin  of  Species,  by  Means  of  Natural  Selection,  or  the 
Preservation  of  a  Favored  Race  in  the  Struggle  for  Life.  By 
CHARLES  DARWIN,  M.A.,  LL.D.,  F.R.S.  Portrait.  12mo,  cloth, 
gilt  top,  $1.00. 

This  book  is  the  grandest  achievement  of  modern  scientific  thought  and 
research.  It  has  passed  through  many  editions  in  English,  has  been  translated 
into  almost  all  the  languages  of  Europe,  and  has  oeen  the  subject  of  more 
reviews,  pamphlets  and  separate  books  than  any  other  volume  of  the  age.— 
Robert  Thome.  _  _____  _ 

For  sale  by  all  Booksellers,  or  will  be  sent  post-paid  on  receipt  of  price,  by  the  pub- 
lisher, A.  L.  BVRT,  66  Keade  Street,  New  York. 


at  tit* 


The  Descent  of  Man.  By  CHARLES  DARWIN.  Portrait.  12mo) 
Illustrated,  cloth,  gilt  top,  $1.00. 

The  Life  and  Adventures  of  Nicholas  Nickleby.  By  CHARLES 
DICKENS.  Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

Nicholas,  the  hero  of  the  tale  is  a  young:  man  of  impetuous  temper,  not 
always  blameless  in  his  actions,  indeed,  not  always  agreeable,  yet  upon  the 
whole,  so  manly,  so  honest  and  so  lovable,  that  we  overlook  his  faults,  and 
sympathize  with  him  in  his  misfortunes,  and  rejoice  with  him  in  his  successes. 


Lucile.  By  OWEN  MEREDITH  (Edward  Robert  Bulwer-Lytton) 
Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

In  the  character  of  Lucile  we  have  the  author's  highest  and  purest  embodi 
»nent  of  intellect  and  virtue.  First  subduing  her  own  nature,  she  is  content  to 
spend  all  the  treasures  of  her  life  and  genius  in  offices  of  well-doing,  and  from 
the  heart  of  a  woman  thoroughly  true  and  good,  and  ever  ready  for  self-sacri- 
fice, she  finally  diffuses  health  and  strength  into  the  hearts  of  all  around  her. 

The  Posthumous  Papers  of  the  Pickwick  Club.  By  CHARLES 
DICKENS.  Portrait.  12mo,  cloth,  gilt  top  $1.00. 

The  Pickwick  Papers  chronicle  the  travels  and  adventures  of  the  immortal 
Mr.  Pickwick  and  his  fellow  members  of  the  Pickwick  Club,  and  the  varied 
pictures  of  life  through  which  we  follow  the  kind  old  bachelor,  his  three  friends 
and  his  attached  servant,  the  inimitable  Sam  Weller,  are  of  absorbing  interest. 

First  Principles.  By  HERBERT  SPENCER.  Portrait.  12ino, 
cloth,  gilt  top,  $1.00. 

The  Personal  History  of  David  Copperfield.  By  CHARLES 
DICKENS.  Portrait.  12ino,  cloth,  gilt  top,  $1.00. 

David  Copperfield  is  a  novel  full  of  tenderness  and  purity  of  feeling,  and  in 
it  Dickens  presents  to  the  full  that  comprehensiveness  of  sympathy  which 
springs  from  a  sense  of  brotherhood  with  all  mankind. 

The  Old  Curiosity  Shop.  By  CHARLES  DICKENS.  Portrait 
12mo,  cloth,  gilt  top,  $1.00. 

"  The  Old  Curiosity  Shop  '*  abounds  with  vivid  descriptions  of  human  life  and 
character,  and  the  reader's  atte 


ntion  is  held  until  the  very  end 
hich  appeals  m 
this  story  of  childish  abnegation  and  devotion. 


,  ... 

Dickens'  works  there  is  none  which  appeals  more  strongly  to  our  heart  than 

dev 


Middlemarch:  A  Study  of  Provincial  Life.  By  GEORGE 
ELIOT.  Portrait.  12ino,  cloth,  gilt  top,  $1.00. 

"  Middlemarch  "  is  a  study  of  ProvLicial  life,  and  is  unquestionably  one  of 
the  strongest  of  English  novels.  .  .  .  It  is  a  picture,  vast,  swarming,  deep 
colored,  crowded  with  episodes,  with  vivid  images,  with  lurking  master  strokes. 
with  brilliant  passages  of  expression,  and  as  such  we  may  freely  accept  and 
enjoy  it. 

The  Life  of  Christ.  By  FREDERIC  W.  FARRAR,  D.D.,  F.  R.  S. 
Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

Great  ability,  ripe  literary  skill,  graphic  description  and  a  fine  spiritual  insight 
are  conspicuous  in  every  chapter  and  taken  altogether  it  is  the  most  marked  of 
all  the  many  attempts  in  our  own  days  to  present  to  us  the  human  life  of  the 
Savior  of  mankind. 

For  sale  by  all  Booksellers,  or  will  be  sent  post-paid  on  receipt  of  price,  by  the  pub 
fisher,  A.  JL.  BVRT,  66  Xteade  St.,  New  York. 


jjuvt'g  tptorog  gnfce  lEwld'a  gjttt 

Past  and  Present.    By  THOMAS  CARLYLE,  with  an  introductory 
note  by  Robert  Thome,  M.A.    Portrait.    12mo,  cloth,  gilt  top,  $1.00. 
His  (Carlyle's)  bidding  is  to  do  the  allotted  work  of  life  silently  and  bravely, 
and  there  is  probably  no  person  who  has  not  gained  strength  by  the  reading  of 
bis  strong  and  earnest  writings. — Robert  Thorne. 

The  History  of  Civilization  in  Europe.  By  FRANCOIS  PIERRE 
GUILLAUME  GUIZOT.  Translated  by  William  Hazlitt,  with  a  bio- 
graphical  sketch  of  the  author.  Portrait.  12mo.  cloth,  gilt  top, 
§1.00. 

These  lectures  made  a  profound  impression  at  the  time  they  were  delivered 
tmd  published,  and  indeed  marked  an  epoch  in  the  history  of  education,  rais- 
ing the  reputation  of  their  author  at  once  to  the  highest  point  of  fame,  and 
placing  him  among  the  best  writers  of  France  and  of  Europe. — Eobert  Thorne. 
Ivanhoe.  A  Romance.  By  SIR  WALTER  SCOTT,  Bart.  Reprinted 
from  the  author's  edition,  unaltered  and  unabridged.  Portrait. 
iSmo,  cloth,  gilt  top,  $1.00. 

Ivanhoe  is  one  of  the  most  famous  and  brilliant  of  all  the  master  romances 
of  Sir  Walter  Scott,  who  is  placed  by  many  at  the  head  of  modern  novelists. 
.  .  .  The  breadth  and  power  of  Scott's  style  and  his  charm  as  a  story-teller 
are  too  well  known  to  need  comment,  and  in  this  volume  we  have  him  at  his 
best.— Robert  Thorne. 

The  Vicar  of  Wakefield,  The  Traveller,  and  The  Deserted 

Village.     By  OLIVER  GOLDSMITH.     With  a  Life  of  Goldsmith  by 
WILLIAM  BLACK.     Portrait.     12mo,  cloth,  gilt  top,  $1  00. 

The  style  is  easy  and  delightful.  The  humor  is  delicate  and  all  good  humor; 
there  is  hardly  a  trace  of  satire  or  ill-nature  in  the  whole  book,  which  is  a  true 
expression  of  the  spirit  of  Goldsmith  himself,  one  of  the  most  lovable  person- 
alities in  the  world  of  letters.— Robert  Thorne. 

The  Discourses  of  Epictetus,  with  the  Encheiridion  and  Frag- 
ments. Translated  with  notes,  a  life  of  Epictetus,  a  view  of  his 
philosophy,  and  index.  By  GEORGE  LONG,  M.A.  Portrait.  12mo, 
cloth,  gilt  top,  $1.00. 

Great  purity,  sustained  reflection,  wealth  of  illustration  and  allusion,  vivid 
revelations  of  character  and  brilliant  bursts  of  eloquence,  mark  the  utterances 
of  this  great  teacher  and  insure  their  immortality.—  Frank  Parsons. 

The  Crown  of  Wild  Olive  and  Sesame  and  Lilies.  By  JOHN 
RUSK.IN,  LL.D  Portrait.  !2mo,  cloth,  gilt  top,  $1.00. 

As  a  great  and  fearless  leader  of  thought  and  antagonistic  to  many  features 
of  our  social  order,  he  is  naturally  the  object  of  much  violent  criticism,  but  is 
warmly  admired  and  loved  by  a  great  part  of  the  reading  world,  and  coming 
iges  will  accord  him  his  due.  He  has  told  the  world  new  truth  and  the  world 
will  grow  up  to  his  majestic  stature. — Robert  Thorne. 

The  Meditations  of  the  Emperor  Marcus  Aurelius  Antoninus. 
Translated  by  GEORGE  LONG,  M.A.,  with  a  biographical  sketch  and 
a  view  of  the  philosophy  of  Antoninus  by  the  translator.  Including 
also  an  essay  on  Marcus  Aurelius  by  Canon  Farrar.  Portrait.  12mo, 
cloth,  gilt  top,  $1.00. 

"  The  noblest  book  of  antiquity  "  is  Canon  Farrar's  estimate  of  the  "  Medita- 
tions o"  Marcus  Aurelius ;"  and  his  regard  is  shared  by  thousands  who  have 
been  made  better  and  truer  men  by  the  ennobling  influence  of  the  great  soul 
and  lo'.ty  character  of  *his  pagan  emperor.— Robert  Thorne. 

Foi  •'  file  by  all  Booksellers,  or  will  be  sent  post-paid  on  receipt  of  price,  by  t/te  pub* 
lieher,  *i.  f"  &  URT,  6<?  Jt«ude  Street,  New  York. 


John  Halifax,  Gentleman.  A  Norel.  By  Miss  MULOCK.  Por- 
trait. 12mo,  cloth,  gilt  top,  $1.00. 

The  book  is  from  the  pen  of  one  who  combines  a  careful  study  of  life  with  a 
rare  genius  in  depicting  its  real  experiences,  and  who  renders  charming  even 
a  simple  story  of  actual  life,  by  the  gloiy  of  a  warm  and  loving  heart  with 
Which  she  transfuses  ft.— Frederick  Mynon  Cooper. 

Undine  and  Other  Tales.  By  DE  LA  MOTTE  FOUQUE.  Trans 
lated  from  the  German  by  F.  E.  BUNNETT.  Portrait.  12rno,  cloth, 
gilt  top,  $1.00. 

Undine  has  become  a  household  book  for  old  and  young  in  Germany,  and 
has  been  translated  into  almost  every  European  language.  There  is  in  it  a 
simplicity  of  style  unsurpassed,  and  plenty  of  sweet  pathos  wThich  wets  the 
eye  but  never  wrings  the  heart.—  Henry  Prentice. 

Uarda,  A  Romance  of  Ancient  Egypt.  By  GEORGE  EBERS. 
Translated  from  the  German  by  CLARA  BELL.  12mo,  cloth,  gilt 
top,  $1.00. 

Amid  all  the  tempest  of  passion  and  expectation  incidental  to  such  a  tale 
the  novelist  evolves  a  charming  story  of  love  and  constancy  rising  superior  to 
class  prejudices,  and  of  the  sweet  amenities  of  social  ties  and  family  affection, 
—Frederick  Mynon  Cooper. 

Confessions  of  an  English  Opium-Eater  and  Selected  Essays, 
By  THOMAS  DE  QTJINCEY.  Edited  with  notes  by  DAVID  MASSON, 
Professor  of  English  Literature  in  the  University  of  Edinburgh. 
Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

De  Quincey's  skill  in  narration,  his  rare  pathos,  his  wide  sympathies,  the 
pomp  of  his  dream-descriptions,  his  abounding  though  subtle  humor,  commend 
nim  to  a  large  class  of  readers.— Encyclopedia  Britannica. 

On  the  Heights.  By  BERTHOLD  AUERBACH.  Translated  from 
the  German  by  F.  E.  JJUNNETT.  Portrait.  12mo,  cloth,  gilt  top, 

Auerbach  has  been  called  the  Charles  Dickenc  of  Germany.  He  is  not  only 
a  brilliant  writer  of  fiction,  but  is  at  the  same  time  a  profound  thinker  and 
elevated  moralist.  In  "  On  the  Heights,"  his  most  powerful  work,  education, 
labor,  wealth,  poverty,  and  the  relations  of  rich  and  poor:  aristocracy,  relig- 
ion and  philosophy,  the  rights  of  the  individual,  and  their  various  applications 
to  our  daily  life,  are  illumed  and  illustrated  by  its  progress  and  development. 
It  is  a  beautiful  story,  sad  in  its  ending,  but  free  from  any  tinge  of  coarseness 
or  sensationalism;  pure,  sweet,  warm  with  human  love  and  tenderness.  - 
Frederick  Mynon  Cooper. 

The  Last  Days  of  Pompeii.  By  SIR  EDWARD  BTJLWER-LYTTON 
BART.  Portrait.  12mo,  cloth,  gilt  top,  $1.00. 

The  fate  of  the  rich  Campanian  city,  the  most  awful  catastrophe  which 
history  records,  supplies  a  superb  climax  to  the  story.  This  is  dramatic  and 
powerful  throughout,  and  of  absorbing  interest.  The  characters,  arise  natur- 
ally from  the  scene  of  the  story,  and  they  move  and  speak  in  perfect  accord 
with  their  surroundings;  with  a  human  sympathy  which  easily  bridges  the 
eighteen  centuries  which  have  rolled  over  the  buried  city,  we  follow  with  eager 
interest  this  tale  of  the  men  and  women  of  ancient  Pompeii. — Robert  Thorne. 

For  sale  by  all  Booksellers,  or  will  be  sent  post-paid  on  receipt  of  price,  by  the  pub 
fisher.  4-.  Z>.  BU&T,  66  Kende  Street,  New  fork. 


An  Egyptian  Prii 
cloth,  gilt  top,  $1.00. 


Princess.    By  GEORGE  EBERS.    Portrait.     12mo, 


Kenilworth.    By  SIB  WALTER  SCOTT.    Portrait.     12nm  cloth. 
gilt  top,  $1.00. 

The  History  of  Henry  Esmond,  Esq.     By  WILLIAM  MAKE 
PEACE  THACKERAY.     Portrait.     12ino,  cloth,  gilt  top,  $1.00. 

Mosses  from  an   Old  Manse.     By  NATHANIEL  HAWTHORNE. 
Portrait.     12mo,  cloth,  gilt  top,  $1.00. 

The  Light   of  Asia,  or  The  Great  Renunciation.      By  Eowitf 
ARNOLD,  M.A.     Portrait.     ISmo,  cloth,  gilt  top,  $1.00. 

Les  Miserables.    A  Novel.    By  VICTOR  HUGO.   Illustrated.   Two 
vols.,  12ino,  cloth,  gilt  top,  each  $1.00. 

The  Count  of  Monte  Cristo.    By  ALEXANDRE  DUMAS.     Illus- 
trated.    Two  vols.,  12mo,  cloth,  gilt  top,  each  $1.00. 

Heroes,  Hero-Worship  and  the  Heroic  in  History.     By  THOMAS 
CARLYLE.     Portrait.     12mo,  cloth,  gilt  top,  $1.00. 

Around  the  World  in  the  Yacht  Sunbeam.    By  MRS.  BRASSEY. 
Portrait.     12ino,  cloth,  gilt  top,  $1.00. 

Picciola,  or  the  Prison  Flower.     By  X.  B.  SAINTINE.     Portrait. 
12mo,  cloth,  gilt  top,  $1.00. 

The  Scarlet  Letter.     By  NATHANIEL  HAWTHORNE.     Portrait 
12ino,  cloth,  gilt  top,  $1.00. 

East  Lynne.    Ry  MRS.  HENRY  WOOD.    Portrait.     12ino,  cloth, 
gilt  top,  $1.00. 

The  Woman  in  White.    By  WILKIE  COLLINS.    Portrait.    12mo, 
cloth,  gilt  top,  $1.00. 

For  sale  by  all  Booksellers,  or  will  be  gent  post-paid  on  receipt  of  price,  by  the  pub- 
Usher,  A.  £.  BURT,  66  Meade  St.*  New  fork. 


University  of  California 

SOUTHERN  REGIONAL  LIBRARY  FACILITY 

305  De  Neve  Drive  -  Parking  Lot  17  •  Box  951388 

LOS  ANGELES,  CALIFORNIA  90095-1388 
Return  this  material  to  the  library  from  which  it  was  borrowed. 


rJAN  1  5  2002 

SRLF 
QUARTER  LOAIS 


THE  LIBRARY 

OF  CALIFORNIA 
U>S  ANGELES 


6*<~ 


0171 

T97f 
1890 


000673421     4 


